/src/opensc/src/libopensc/asn1.c

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/*
 * asn1.c: ASN.1 decoding functions (DER)
 *
 * Copyright (C) 2001, 2002  Juha Yrjölä <juha.yrjola@iki.fi>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <assert.h>
#include <ctype.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#include "internal.h"
#include "asn1.h"

static int asn1_decode(sc_context_t *ctx, struct sc_asn1_entry *asn1,
           const u8 *in, size_t len, const u8 **newp, size_t *len_left,
           int choice, int depth);
static int asn1_encode(sc_context_t *ctx, const struct sc_asn1_entry *asn1,
           u8 **ptr, size_t *size, int depth);
static int asn1_write_element(sc_context_t *ctx, unsigned int tag,
    const u8 * data, size_t datalen, u8 ** out, size_t * outlen);

static const char *tag2str(unsigned int tag)
{
  static const char *tags[] = {
    "EOC", "BOOLEAN", "INTEGER", "BIT STRING", "OCTET STRING",  /* 0-4 */
    "NULL", "OBJECT IDENTIFIER", "OBJECT DESCRIPTOR", "EXTERNAL", "REAL", /* 5-9 */
    "ENUMERATED", "Universal 11", "UTF8String", "Universal 13", /* 10-13 */
    "Universal 14", "Universal 15", "SEQUENCE", "SET",  /* 15-17 */
    "NumericString", "PrintableString", "T61String",  /* 18-20 */
    "VideotexString", "IA5String", "UTCTIME", "GENERALIZEDTIME",  /* 21-24 */
    "GraphicString", "VisibleString", "GeneralString",  /* 25-27 */
    "UniversalString", "Universal 29", "BMPString"  /* 28-30 */
  };

  if (tag > 30)
    return "(unknown)";
  return tags[tag];
}

int sc_asn1_read_tag(const u8 ** buf, size_t buflen, unsigned int *cla_out,
         unsigned int *tag_out, size_t *taglen)
{
  const u8 *p = *buf;
  size_t left = buflen, len;
  unsigned int cla, tag, i;

  *buf = NULL;

  if (left == 0 || !p || buflen == 0)
    return SC_ERROR_INVALID_ASN1_OBJECT;
  if (*p == 0xff || *p == 0) {
    /* end of data reached */
    *taglen = 0;
    *tag_out = SC_ASN1_TAG_EOC;
    return SC_SUCCESS;
  }

  /* parse tag byte(s)
   * Resulted tag is presented by integer that has not to be
   * confused with the 'tag number' part of ASN.1 tag.
   */
  cla = (*p & SC_ASN1_TAG_CLASS) | (*p & SC_ASN1_TAG_CONSTRUCTED);
  tag = *p & SC_ASN1_TAG_PRIMITIVE;
  if (left < 1)
    return SC_ERROR_INVALID_ASN1_OBJECT;
  p++;
  left--;
  if (tag == SC_ASN1_TAG_PRIMITIVE) {
    /* high tag number */
    size_t n = SC_ASN1_TAGNUM_SIZE - 1;
    /* search the last tag octet */
    do {
      if (left == 0 || n == 0)
        /* either an invalid tag or it doesn't fit in
         * unsigned int */
        return SC_ERROR_INVALID_ASN1_OBJECT;
      tag <<= 8;
      tag |= *p;
      p++;
      left--;
      n--;
    } while (tag & 0x80);
  }

  /* parse length byte(s) */
  if (left == 0)
    return SC_ERROR_INVALID_ASN1_OBJECT;
  len = *p;
  p++;
  left--;
  if (len & 0x80) {
    len &= 0x7f;
    unsigned int a = 0;
    if (len > sizeof a || len > left)
      return SC_ERROR_INVALID_ASN1_OBJECT;
    for (i = 0; i < len; i++) {
      a <<= 8;
      a |= *p;
      p++;
      left--;
    }
    len = a;
  }

  *cla_out = cla;
  *tag_out = tag;
  *taglen = len;
  *buf = p;

  if (len > left)
    return SC_ERROR_ASN1_END_OF_CONTENTS;

  return SC_SUCCESS;
}

void sc_format_asn1_entry(struct sc_asn1_entry *entry, void *parm, void *arg,
        int set_present)
{
  entry->parm = parm;
  entry->arg  = arg;
  if (set_present)
    entry->flags |= SC_ASN1_PRESENT;
}

void sc_copy_asn1_entry(const struct sc_asn1_entry *src,
      struct sc_asn1_entry *dest)
{
  while (src->name != NULL) {
    *dest = *src;
    dest++;
    src++;
  }
  dest->name = NULL;
}

static void print_indent(size_t depth)
{
  for (; depth > 0; depth--) {
    putchar(' ');
  }
}

static void print_hex(const u8 * buf, size_t buflen, size_t depth)
{
  size_t lines_len = buflen * 5 + 128;
  char *lines = malloc(lines_len);
  char *line = lines;

  if (buf == NULL || buflen == 0 || lines == NULL) {
    free(lines);
    return;
  }

  sc_hex_dump(buf, buflen, lines, lines_len);

  while (*line != '\0') {
    char *line_end = strchr(line, '\n');
    ptrdiff_t width = line_end - line;
    if (!line_end || width <= 1) {
      /* don't print empty lines */
      break;
    }
    if (buflen > 8) {
      putchar('\n');
      print_indent(depth);
    } else {
      printf(": ");
    }
    printf("%.*s", (int) width, line);
    line = line_end + 1;
  }

  free(lines);
}

static void print_ascii(const u8 * buf, size_t buflen)
{
  for (; 0 < buflen; buflen--, buf++) {
    if (isprint(*buf))
      printf("%c", *buf);
    else
      putchar('.');
  }
}

static void sc_asn1_print_octet_string(const u8 * buf, size_t buflen, size_t depth)
{
  print_hex(buf, buflen, depth);
}

static void sc_asn1_print_utf8string(const u8 * buf, size_t buflen)
{
  /* FIXME UTF-8 is not ASCII */
  print_ascii(buf, buflen);
}

static void sc_asn1_print_integer(const u8 * buf, size_t buflen)
{
  size_t a = 0;

  if (buflen > sizeof(a)) {
    printf("0x%s", sc_dump_hex(buf, buflen));
  } else {
    size_t i;
    for (i = 0; i < buflen; i++) {
      a <<= 8;
      a |= buf[i];
    }
    printf("%"SC_FORMAT_LEN_SIZE_T"u", a);
  }
}

static void sc_asn1_print_boolean(const u8 * buf, size_t buflen)
{
  if (!buflen)
    return;

  if (buf[0])
    printf("true");
  else
    printf("false");
}

static void sc_asn1_print_bit_string(const u8 * buf, size_t buflen, size_t depth)
{
#ifndef _WIN32
  long long a = 0;
#else
  __int64 a = 0;
#endif
  int r, i;

  if (buflen > sizeof(a) + 1) {
    print_hex(buf, buflen, depth);
  } else {
    r = sc_asn1_decode_bit_string(buf, buflen, &a, sizeof(a), 1);
    if (r < 0) {
      printf("decode error, ");
      /* try again without the strict mode */
      r = sc_asn1_decode_bit_string(buf, buflen, &a, sizeof(a), 0);
      if (r < 0) {
        printf("even for lax decoding");
        return ;
      }
    }
    for (i = r - 1; i >= 0; i--) {
      printf("%c", ((a >> i) & 1) ? '1' : '0');
    }
  }
}

#ifdef ENABLE_OPENSSL
#include <openssl/objects.h>

static void openssl_print_object_sn(const char *s)
{
  ASN1_OBJECT *obj = OBJ_txt2obj(s, 0);
  if (obj) {
    int nid = OBJ_obj2nid(obj);
    if (nid != NID_undef) {
      printf(", %s", OBJ_nid2sn(nid));
    }
    ASN1_OBJECT_free(obj);
  }
}
#else
static void openssl_print_object_sn(const char *s)
{
}
#endif

static void sc_asn1_print_object_id(const u8 * buf, size_t buflen)
{
  struct sc_object_id oid;
  const char *sbuf;

  if (sc_asn1_decode_object_id(buf, buflen, &oid)) {
    printf("decode error");
    return;
  }

  sbuf = sc_dump_oid(&oid);
  printf(" %s", sbuf);
  openssl_print_object_sn(sbuf);
}

static void sc_asn1_print_utctime(const u8 * buf, size_t buflen)
{
  if (buflen < 8) {
    printf("Error in decoding.\n");
    return;
  }

  print_ascii(buf, 2);    /* YY */
  putchar('-');
  print_ascii(buf+2, 2);    /* MM */
  putchar('-');
  print_ascii(buf+4, 2);    /* DD */
  putchar(' ');
  print_ascii(buf+6, 2);    /* hh */
  buf += 8;
  buflen -= 8;
  if (buflen >= 2 && isdigit(buf[0]) && isdigit(buf[1])) {
    putchar(':');
    print_ascii(buf, 2);  /* mm */
    buf += 2;
    buflen -= 2;
  }
  if (buflen >= 2 && isdigit(buf[0]) && isdigit(buf[1])) {
    putchar(':');
    print_ascii(buf, 2);  /* ss */
    buf += 2;
    buflen -= 2;
  }
  if (buflen >= 4 && '.' == buf[0]) {
    print_ascii(buf, 4);  /* fff */
    buf += 4;
    buflen -= 4;
  }

  if (buflen >= 1 && 'Z' == buf[0]) {
    printf(" UTC");
  } else if (buflen >= 5 && ('-' == buf[0] || '+' == buf[0])) {
    putchar(' ');
    print_ascii(buf, 3);  /* +/-hh */
    putchar(':');
    print_ascii(buf+3, 2);  /* mm */
  }
}

static void sc_asn1_print_generalizedtime(const u8 * buf, size_t buflen)
{
  if (buflen < 8) {
    printf("Error in decoding.\n");
    return;
  }

  print_ascii(buf, 2);
  sc_asn1_print_utctime(buf + 2, buflen - 2);
}

static void print_tags_recursive(const u8 * buf0, const u8 * buf,
         size_t buflen, size_t depth)
{
  int r;
  size_t i;
  size_t bytesleft = buflen;
  const char *classes[4] = {
    "Universal",
    "Application",
    "Context",
    "Private"
  };
  const u8 *p = buf;

  while (bytesleft >= 2) {
    unsigned int cla = 0, tag = 0;
    size_t hlen;
    const u8 *tagp = p;
    size_t len;

    r = sc_asn1_read_tag(&tagp, bytesleft, &cla, &tag, &len);
    if (r != SC_SUCCESS || (tagp == NULL && tag != SC_ASN1_TAG_EOC)) {
      printf("Error in decoding.\n");
      return;
    }
    hlen = tagp - p;
    if (cla == 0 && tag == 0) {
      printf("Zero tag, finishing\n");
      break;
    }
    print_indent(depth);
    /* let i be the length of the tag in bytes */
    for (i = 1; i < sizeof tag - 1; i++) {
      if (!(tag >> 8*i))
        break;
    }
    printf("%02X", cla<<(i-1)*8 | tag);

    if ((cla & SC_ASN1_TAG_CLASS) == SC_ASN1_TAG_UNIVERSAL) {
      printf(" %s", tag2str(tag));
    } else {
      printf(" %s %-2u",
          classes[cla >> 6],
          i == 1 ? tag & SC_ASN1_TAG_PRIMITIVE : tag & (((unsigned int) ~0) >> (i-1)*8));
    }
    if (!((cla & SC_ASN1_TAG_CLASS) == SC_ASN1_TAG_UNIVERSAL
          && tag == SC_ASN1_TAG_NULL && len == 0)) {
      printf(" (%"SC_FORMAT_LEN_SIZE_T"u byte%s)",
          len,
          len != 1 ? "s" : "");
    }

    if (len + hlen > bytesleft) {
      printf(" Illegal length!\n");
      return;
    }
    p += hlen + len;
    bytesleft -= hlen + len;

    if (cla & SC_ASN1_TAG_CONSTRUCTED) {
      putchar('\n');
      print_tags_recursive(buf0, tagp, len, depth + 2*i + 1);
      continue;
    }

    switch (tag) {
      case SC_ASN1_TAG_BIT_STRING:
        printf(": ");
        sc_asn1_print_bit_string(tagp, len, depth + 2*i + 1);
        break;
      case SC_ASN1_TAG_OCTET_STRING:
        sc_asn1_print_octet_string(tagp, len, depth + 2*i + 1);
        break;
      case SC_ASN1_TAG_OBJECT:
        printf(": ");
        sc_asn1_print_object_id(tagp, len);
        break;
      case SC_ASN1_TAG_INTEGER:
      case SC_ASN1_TAG_ENUMERATED:
        printf(": ");
        sc_asn1_print_integer(tagp, len);
        break;
      case SC_ASN1_TAG_IA5STRING:
      case SC_ASN1_TAG_PRINTABLESTRING:
      case SC_ASN1_TAG_T61STRING:
      case SC_ASN1_TAG_UTF8STRING:
        printf(": ");
        sc_asn1_print_utf8string(tagp, len);
        break;
      case SC_ASN1_TAG_BOOLEAN:
        printf(": ");
        sc_asn1_print_boolean(tagp, len);
        break;
      case SC_ASN1_GENERALIZEDTIME:
        printf(": ");
        sc_asn1_print_generalizedtime(tagp, len);
        break;
      case SC_ASN1_UTCTIME:
        printf(": ");
        sc_asn1_print_utctime(tagp, len);
        break;
    }

    if ((cla & SC_ASN1_TAG_CLASS) == SC_ASN1_TAG_APPLICATION) {
      print_hex(tagp, len, depth + 2*i + 1);
    }

    if ((cla & SC_ASN1_TAG_CLASS) == SC_ASN1_TAG_CONTEXT) {
      print_hex(tagp, len, depth + 2*i + 1);
    }

    putchar('\n');
  }
}

void sc_asn1_print_tags(const u8 * buf, size_t buflen)
{
  print_tags_recursive(buf, buf, buflen, 0);
}

const u8 *sc_asn1_find_tag(sc_context_t *ctx, const u8 * buf,
  size_t buflen, unsigned int tag_in, size_t *taglen_in)
{
  size_t left = buflen, taglen;
  const u8 *p = buf;

  *taglen_in = 0;
  while (left >= 2) {
    unsigned int cla = 0, tag, mask = 0xff00;

    buf = p;
    /* read a tag */
    if (sc_asn1_read_tag(&p, left, &cla, &tag, &taglen) != SC_SUCCESS
        || p == NULL)
      return NULL;

    left -= (p - buf);
    /* we need to shift the class byte to the leftmost
     * byte of the tag */
    while ((tag & mask) != 0) {
      cla  <<= 8;
      mask <<= 8;
    }
    /* compare the read tag with the given tag */
    if ((tag | cla) == tag_in) {
      /* we have a match => return length and value part */
      if (taglen > left)
        return NULL;
      *taglen_in = taglen;
      return p;
    }
    /* otherwise continue reading tags */
    left -= taglen;
    p += taglen;
  }
  return NULL;
}

const u8 *sc_asn1_skip_tag(sc_context_t *ctx, const u8 ** buf, size_t *buflen,
         unsigned int tag_in, size_t *taglen_out)
{
  const u8 *p = *buf;
  size_t len = *buflen, taglen;
  unsigned int cla = 0, tag;

  if (sc_asn1_read_tag((const u8 **) &p, len, &cla, &tag, &taglen) != SC_SUCCESS
      || p == NULL)
    return NULL;
  switch (cla & 0xC0) {
  case SC_ASN1_TAG_UNIVERSAL:
    if ((tag_in & SC_ASN1_CLASS_MASK) != SC_ASN1_UNI)
      return NULL;
    break;
  case SC_ASN1_TAG_APPLICATION:
    if ((tag_in & SC_ASN1_CLASS_MASK) != SC_ASN1_APP)
      return NULL;
    break;
  case SC_ASN1_TAG_CONTEXT:
    if ((tag_in & SC_ASN1_CLASS_MASK) != SC_ASN1_CTX)
      return NULL;
    break;
  case SC_ASN1_TAG_PRIVATE:
    if ((tag_in & SC_ASN1_CLASS_MASK) != SC_ASN1_PRV)
      return NULL;
    break;
  }
  if (cla & SC_ASN1_TAG_CONSTRUCTED) {
    if ((tag_in & SC_ASN1_CONS) == 0)
      return NULL;
  } else
    if (tag_in & SC_ASN1_CONS)
      return NULL;
  if ((tag_in & SC_ASN1_TAG_MASK) != tag)
    return NULL;
  len -= (p - *buf);  /* header size */
  if (taglen > len) {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1,
       "too long ASN.1 object (size %"SC_FORMAT_LEN_SIZE_T"u while only %"SC_FORMAT_LEN_SIZE_T"u available)\n",
       taglen, len);
    return NULL;
  }
  *buflen -= (p - *buf) + taglen;
  *buf = p + taglen;  /* point to next tag */
  *taglen_out = taglen;
  return p;
}

const u8 *sc_asn1_verify_tag(sc_context_t *ctx, const u8 * buf, size_t buflen,
           unsigned int tag_in, size_t *taglen_out)
{
  return sc_asn1_skip_tag(ctx, &buf, &buflen, tag_in, taglen_out);
}

static int decode_bit_string(const u8 * inbuf, size_t inlen, void *outbuf,
           size_t outlen, int invert, const int strict)
{
  const u8 *in = inbuf;
  u8 *out = (u8 *) outbuf;
  int i, count = 0;
  int zero_bits;
  size_t octets_left;

  if (inlen < 1)
    return SC_ERROR_INVALID_ASN1_OBJECT;

  /* The formatting is only enforced by SHALL keyword so we should accept
   * by default also non-strict values. */
  if (strict) {
    /* 8.6.2.3 If the bitstring is empty, there shall be no
     * subsequent octets,and the initial octet shall be zero. */
    if (inlen == 1 && *in != 0)
      return SC_ERROR_INVALID_ASN1_OBJECT;
    /* ITU-T Rec. X.690 8.6.2.2: The number shall be in the range zero to seven. */
    if ((*in & ~0x07) != 0)
      return SC_ERROR_INVALID_ASN1_OBJECT;
  }

  memset(outbuf, 0, outlen);
  zero_bits = *in & 0x07;
  in++;
  octets_left = inlen - 1;
  if (outlen < octets_left)
    return SC_ERROR_BUFFER_TOO_SMALL;

  while (octets_left) {
    /* 1st octet of input:  ABCDEFGH, where A is the MSB */
    /* 1st octet of output: HGFEDCBA, where A is the LSB */
    /* first bit in bit string is the LSB in first resulting octet */
    int bits_to_go;

    *out = 0;
    if (octets_left == 1 && zero_bits > 0) {
      bits_to_go = 8 - zero_bits;
      /* Verify the padding is zero bits */
      if (*in & (1 << (zero_bits-1))) {
        return SC_ERROR_INVALID_ASN1_OBJECT;
      }
    } else
      bits_to_go = 8;
    if (invert)
      for (i = 0; i < bits_to_go; i++) {
        *out |= ((*in >> (7 - i)) & 1) << i;
      }
    else {
      *out = *in;
    }
    out++;
    in++;
    octets_left--;
    count++;
  }
  return (count * 8) - zero_bits;
}

int sc_asn1_decode_bit_string(const u8 * inbuf, size_t inlen,
            void *outbuf, size_t outlen, const int strict)
{
  return decode_bit_string(inbuf, inlen, outbuf, outlen, 1, strict);
}

int sc_asn1_decode_bit_string_ni(const u8 * inbuf, size_t inlen,
         void *outbuf, size_t outlen, const int strict)
{
  return decode_bit_string(inbuf, inlen, outbuf, outlen, 0, strict);
}

static int encode_bit_string(const u8 * inbuf, size_t bits_left, u8 **outbuf,
           size_t *outlen, int invert)
{
  const u8 *in = inbuf;
  u8 *out;
  size_t bytes, skipped = 0;

  bytes = BYTES4BITS(bits_left) + 1;
  *outbuf = out = malloc(bytes);
  if (out == NULL)
    return SC_ERROR_OUT_OF_MEMORY;
  *outlen = bytes;
  out += 1;
  while (bits_left) {
    size_t i, bits_to_go = 8;

    *out = 0;
    if (bits_left < 8) {
      bits_to_go = bits_left;
      skipped = 8 - bits_left;
    }
    if (invert) {
      for (i = 0; i < bits_to_go; i++)
        *out |= ((*in >> i) & 1) << (7 - i);
    } else {
      *out = *in;
      if (bits_left < 8)
        return SC_ERROR_NOT_SUPPORTED; /* FIXME */
    }
    bits_left -= bits_to_go;
    out++, in++;
  }
  out = *outbuf;
  out[0] = skipped;
  return 0;
}

/*
 * Bitfields are just bit strings, stored in an unsigned int
 * (taking endianness into account)
 */
static int decode_bit_field(const u8 * inbuf, size_t inlen, void *outbuf, size_t outlen, const int strict)
{
  u8    data[sizeof(unsigned int)];
  unsigned int  field = 0;
  int   i, n;

  if (outlen != sizeof(data))
    return SC_ERROR_BUFFER_TOO_SMALL;

  n = decode_bit_string(inbuf, inlen, data, sizeof(data), 1, strict);
  if (n < 0)
    return n;

  for (i = 0; i < n; i += 8) {
    field |= ((unsigned int) data[i/8] << i);
  }
  memcpy(outbuf, &field, outlen);
  return 0;
}

static int encode_bit_field(const u8 *inbuf, size_t inlen,
          u8 **outbuf, size_t *outlen)
{
  u8    data[sizeof(unsigned int)];
  unsigned int  field = 0;
  size_t    i, bits;

  if (inlen != sizeof(data))
    return SC_ERROR_BUFFER_TOO_SMALL;

  /* count the bits */
  memcpy(&field, inbuf, inlen);
  for (bits = 0; field; bits++)
    field >>= 1;

  memcpy(&field, inbuf, inlen);
  for (i = 0; i < bits; i += 8)
    data[i/8] = field >> i;

  return encode_bit_string(data, bits, outbuf, outlen, 1);
}

int sc_asn1_decode_integer(const u8 * inbuf, size_t inlen, int *out, int strict)
{
  int    a = 0, is_negative = 0;
  size_t i = 0;

  if (inlen == 0) {
    return SC_ERROR_INVALID_ASN1_OBJECT;
  }
  if (inlen > sizeof(int)) {
    return SC_ERROR_NOT_SUPPORTED;
  }
  if (inbuf[0] & 0x80) {
    if (strict && inlen > 1 && inbuf[0] == 0xff && (inbuf[1] & 0x80)) {
      return SC_ERROR_INVALID_ASN1_OBJECT;
    }
    is_negative = 1;
    a |= 0xff^(*inbuf++);
    i = 1;
  } else {
    if (strict && inlen > 1 && inbuf[0] == 0x00 && (inbuf[1] & 0x80) == 0) {
      return SC_ERROR_INVALID_ASN1_OBJECT;
    }
  }
  for (; i < inlen; i++) {
    if (a > (INT_MAX >> 8) || a < (INT_MIN + (1<<8))) {
      return SC_ERROR_NOT_SUPPORTED;
    }
    a <<= 8;
    if (is_negative) {
      a |= 0xff^(*inbuf++);
    } else {
      a |= *inbuf++;
    }
  }
  if (is_negative) {
    /* Calculate Two's complement from previously positive number */
    a = (-1 * a) - 1;
  }
  *out = a;
  return 0;
}

static int asn1_encode_integer(int in, u8 ** obj, size_t * objsize)
{
  int i = sizeof(in) * 8, skip_zero, skip_sign;
  u8 *p, b;

  if (in < 0)
  {
    skip_sign = 1;
    skip_zero= 0;
  }
  else
  {
    skip_sign = 0;
    skip_zero= 1;
  }
  *obj = p = malloc(sizeof(in)+1);
  if (*obj == NULL)
    return SC_ERROR_OUT_OF_MEMORY;
  do {
    i -= 8;
    b = in >> i;
    if (skip_sign)
    {
      if (b != 0xff)
        skip_sign = 0;
      if (b & 0x80)
      {
        *p = b;
        if (0xff == b)
          continue;
      }
      else
      {
        p++;
        skip_sign = 0;
      }
    }
    if (b == 0 && skip_zero)
      continue;
    if (skip_zero) {
      skip_zero = 0;
      /* prepend 0x00 if MSb is 1 and integer positive */
      if ((b & 0x80) != 0 && in > 0)
        *p++ = 0;
    }
    *p++ = b;
  } while (i > 0);
  if (skip_sign)
    p++;
  *objsize = p - *obj;
  if (*objsize == 0) {
    *objsize = 1;
    (*obj)[0] = 0;
  }
  return 0;
}

int
sc_asn1_decode_object_id(const u8 *inbuf, size_t inlen, struct sc_object_id *id)
{
  int large_second_octet = 0;
  unsigned int a = 0;
  const u8 *p = inbuf;
  int *octet;

  if (inlen == 0 || inbuf == NULL || id == NULL)
    return SC_ERROR_INVALID_ARGUMENTS;

  sc_init_oid(id);
  octet = id->value;

  /* The first octet can be 0, 1 or 2 and is derived from the first byte */
  a = MIN(*p / 40, 2);
  *octet++ = a;

  /* The second octet fits here if the previous was 0 or 1 and second one is smaller than 40.
   * for the value 2 we can go up to 47. Otherwise the first bit needs to be set
   * and we continue reading further */
  if ((*p & 0x80) == 0) {
    *octet++ = *p - (a * 40);
    inlen--;
  } else {
    large_second_octet = 1;
  }

  while (inlen) {
    if (!large_second_octet)
      p++;
    /* This signalizes empty most significant bits, which means
     * the unsigned integer encoding is not minimal */
    if (*p == 0x80) {
      sc_init_oid(id);
      return SC_ERROR_INVALID_ASN1_OBJECT;
    }
    /* Use unsigned type here so we can process the whole INT range.
     * Values can not be negative */
    a = *p & 0x7F;
    inlen--;
    while (inlen && *p & 0x80) {
      /* Limit the OID values to int size and do not overflow */
      if (a > (UINT_MAX>>7)) {
        sc_init_oid(id);
        return SC_ERROR_NOT_SUPPORTED;
      }
      p++;
      a <<= 7;
      a |= *p & 0x7F;
      inlen--;
    }
    if (*p & 0x80) {
      /* We dropped out from previous cycle on the end of
       * data while still expecting continuation of value */
      sc_init_oid(id);
      return SC_ERROR_INVALID_ASN1_OBJECT;
    }
    if (large_second_octet) {
      a -= (2 * 40);
    }
    if (a > INT_MAX) {
      sc_init_oid(id);
      return SC_ERROR_NOT_SUPPORTED;
    }
    *octet++ = a;
    if (octet - id->value >= SC_MAX_OBJECT_ID_OCTETS)   {
      sc_init_oid(id);
      return SC_ERROR_INVALID_ASN1_OBJECT;
    }
    large_second_octet = 0;
  }

  return 0;
}

int
sc_asn1_encode_object_id(u8 **buf, size_t *buflen, const struct sc_object_id *id)
{
  u8 temp[SC_MAX_OBJECT_ID_OCTETS*5], *p = temp;
  int i;

  if (!buflen || !id)
    return SC_ERROR_INVALID_ARGUMENTS;

  /* an OID must have at least two components */
  if (id->value[0] == -1 || id->value[1] == -1)
    return SC_ERROR_INVALID_ARGUMENTS;

  for (i = 0; i < SC_MAX_OBJECT_ID_OCTETS; i++) {
    unsigned int k, shift;

    if (id->value[i] == -1)
      break;

    k = id->value[i];
    switch (i) {
    case 0:
      if (k > 2)
        return SC_ERROR_INVALID_ARGUMENTS;
      *p = k * 40;
      break;
    case 1:
      if (k > 39 && id->value[0] < 2) {
        return SC_ERROR_INVALID_ARGUMENTS;
      }
      /* We can encode larger IDs to multiple bytes
       * similarly as the following IDs */
      k += *p;
      /* fall through */
    default:
      shift = 28;
      while (shift && (k >> shift) == 0)
        shift -= 7;
      while (shift) {
        *p++ = 0x80 | ((k >> shift) & 0x7f);
        shift -= 7;
      }
      *p++ = k & 0x7F;
      break;
    }
  }

  *buflen = p - temp;

  if (buf)   {
    *buf = malloc(*buflen);
    if (!*buf)
      return SC_ERROR_OUT_OF_MEMORY;
    memcpy(*buf, temp, *buflen);
  }
  return 0;
}

static int sc_asn1_decode_utf8string(const u8 *inbuf, size_t inlen,
            u8 *out, size_t *outlen)
{
  if (inlen+1 > *outlen)
    return SC_ERROR_BUFFER_TOO_SMALL;
  *outlen = inlen+1;
  memcpy(out, inbuf, inlen);
  out[inlen] = 0;
  return 0;
}

/*
 * This assumes the tag is already encoded
 */
int sc_asn1_put_tag(unsigned int tag, const u8 * data, size_t datalen, u8 * out, size_t outlen, u8 **ptr)
{
  size_t c = 0;
  unsigned int tag_len, ii;
  u8 *p = out;
  u8 tag_char[4] = {0, 0, 0, 0};

  /* Check tag */
  if (tag == 0 || tag > 0xFFFFFFFF) {
    /* A tag of 0x00 is not valid and at most 4-byte tag names are supported. */
    return SC_ERROR_INVALID_DATA;
  }
  for (tag_len = 0; tag; tag >>= 8) {
    /* Note: tag char will be reversed order. */
    tag_char[tag_len++] = tag & 0xFF;
  }

  if (tag_len > 1)   {
    if ((tag_char[tag_len - 1] & SC_ASN1_TAG_PRIMITIVE) != SC_ASN1_TAG_ESCAPE_MARKER) {
      /* First byte is not escape marker. */
      return SC_ERROR_INVALID_DATA;
    }
    for (ii = 1; ii < tag_len - 1; ii++) {
      if ((tag_char[ii] & 0x80) != 0x80) {
        /* MS bit is not 'one'. */
        return SC_ERROR_INVALID_DATA;
      }
    }
    if ((tag_char[0] & 0x80) != 0x00) {
      /* MS bit of the last byte is not 'zero'. */
      return SC_ERROR_INVALID_DATA;
    }
  }

  /* Calculate the number of additional bytes necessary to encode the length. */
  /* c+1 is the size of the length field. */
  if (datalen > 127) {
    c = 1;
    while (datalen >> (c << 3))
      c++;
  }
  if (outlen == 0 || out == NULL) {
    /* Caller only asks for the length that would be written. */
    return (int)(tag_len + (c + 1) + datalen);
  }
  /* We will write the tag, so check the length. */
  if (outlen < tag_len + (c+1) + datalen)
    return SC_ERROR_BUFFER_TOO_SMALL;
  for (ii=0;ii<tag_len;ii++)
    *p++ = tag_char[tag_len - ii - 1];

  if (c > 0) {
    *p++ = 0x80 | c;
    while (c--)
      *p++ = (datalen >> (c << 3)) & 0xFF;
  }
  else {
    *p++ = datalen & 0x7F;
  }
  if(data && datalen > 0) {
    memcpy(p, data, datalen);
    p += datalen;
  }
  if (ptr != NULL)
    *ptr = p;
  return 0;
}

int sc_asn1_write_element(sc_context_t *ctx, unsigned int tag,
  const u8 * data, size_t datalen, u8 ** out, size_t * outlen)
{
  return asn1_write_element(ctx, tag, data, datalen, out, outlen);
}

static int asn1_write_element(sc_context_t *ctx, unsigned int tag,
  const u8 * data, size_t datalen, u8 ** out, size_t * outlen)
{
  unsigned char t;
  unsigned char *buf, *p;
  int c = 0;
  unsigned short_tag;
  unsigned char tag_char[3] = {0, 0, 0};
  size_t tag_len, ii;

  short_tag = tag & SC_ASN1_TAG_MASK;
  for (tag_len = 0; short_tag >> (8 * tag_len); tag_len++)
    tag_char[tag_len] = (short_tag >> (8 * tag_len)) & 0xFF;
  if (!tag_len)
    tag_len = 1;

  if (tag_len > 1)   {
    if ((tag_char[tag_len - 1] & SC_ASN1_TAG_PRIMITIVE) != SC_ASN1_TAG_ESCAPE_MARKER)
      SC_TEST_RET(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_INVALID_DATA, "First byte of the long tag is not 'escape marker'");

    for (ii = 1; ii < tag_len - 1; ii++)
      if (!(tag_char[ii] & 0x80))
        SC_TEST_RET(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_INVALID_DATA, "MS bit expected to be 'one'");

    if (tag_char[0] & 0x80)
      SC_TEST_RET(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_INVALID_DATA, "MS bit of the last byte expected to be 'zero'");
  }

  t = tag_char[tag_len - 1] & 0x1F;

  switch (tag & SC_ASN1_CLASS_MASK) {
  case SC_ASN1_UNI:
    break;
  case SC_ASN1_APP:
    t |= SC_ASN1_TAG_APPLICATION;
    break;
  case SC_ASN1_CTX:
    t |= SC_ASN1_TAG_CONTEXT;
    break;
  case SC_ASN1_PRV:
    t |= SC_ASN1_TAG_PRIVATE;
    break;
  }
  if (tag & SC_ASN1_CONS)
    t |= SC_ASN1_TAG_CONSTRUCTED;
  if (datalen > 127) {
    c = 1;
    while (datalen >> (c << 3))
      c++;
  }

  *outlen = tag_len + 1 + c + datalen;
  buf = malloc(*outlen);
  if (buf == NULL)
    SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_OUT_OF_MEMORY);

  *out = p = buf;
  *p++ = t;
  for (ii=1;ii<tag_len;ii++)
    *p++ = tag_char[tag_len - ii - 1];

  if (c) {
    *p++ = 0x80 | c;
    while (c--)
      *p++ = (datalen >> (c << 3)) & 0xFF;
  }
  else   {
    *p++ = datalen & 0x7F;
  }
  if (datalen && data) {
    memcpy(p, data, datalen);
  }

  return SC_SUCCESS;
}

static const struct sc_asn1_entry c_asn1_path_ext[3] = {
  { "aid",  SC_ASN1_OCTET_STRING, SC_ASN1_APP | 0x0F, 0, NULL, NULL },
  { "path", SC_ASN1_OCTET_STRING, SC_ASN1_TAG_OCTET_STRING, 0, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};
static const struct sc_asn1_entry c_asn1_path[5] = {
  { "path",   SC_ASN1_OCTET_STRING, SC_ASN1_TAG_OCTET_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { "index",  SC_ASN1_INTEGER, SC_ASN1_TAG_INTEGER, SC_ASN1_OPTIONAL, NULL, NULL },
  { "length", SC_ASN1_INTEGER, SC_ASN1_CTX | 0, SC_ASN1_OPTIONAL, NULL, NULL },
/* For some multi-applications PKCS#15 card the ODF records can hold the references to
 * the xDF files and objects placed elsewhere then under the application DF of the ODF itself.
 * In such a case the 'path' ASN1 data includes also the ID of the target application (AID).
 * This path extension do not make a part of PKCS#15 standard.
 */
  { "pathExtended", SC_ASN1_STRUCT, SC_ASN1_CTX | 1 | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static int asn1_decode_path(sc_context_t *ctx, const u8 *in, size_t len,
          sc_path_t *path, int depth)
{
  int idx, count, r;
  struct sc_asn1_entry asn1_path_ext[3], asn1_path[5];
  unsigned char path_value[SC_MAX_PATH_SIZE], aid_value[SC_MAX_AID_SIZE];
  size_t path_len = sizeof(path_value), aid_len = sizeof(aid_value);

  memset(path, 0, sizeof(struct sc_path));

  sc_copy_asn1_entry(c_asn1_path_ext, asn1_path_ext);
  sc_copy_asn1_entry(c_asn1_path, asn1_path);

  sc_format_asn1_entry(asn1_path_ext + 0, aid_value, &aid_len, 0);
  sc_format_asn1_entry(asn1_path_ext + 1, path_value, &path_len, 0);

  sc_format_asn1_entry(asn1_path + 0, path_value, &path_len, 0);
  sc_format_asn1_entry(asn1_path + 1, &idx, NULL, 0);
  sc_format_asn1_entry(asn1_path + 2, &count, NULL, 0);
  sc_format_asn1_entry(asn1_path + 3, asn1_path_ext, NULL, 0);

  r = asn1_decode(ctx, asn1_path, in, len, NULL, NULL, 0, depth + 1);
  if (r)
    return r;

  if (asn1_path[3].flags & SC_ASN1_PRESENT)   {
    /* extended path present: set 'path' and 'aid' */
    memcpy(path->aid.value, aid_value, aid_len);
    path->aid.len = aid_len;

    memcpy(path->value, path_value, path_len);
    path->len = path_len;
  }
  else if (asn1_path[0].flags & SC_ASN1_PRESENT)   {
    /* path present: set 'path' */
    memcpy(path->value, path_value, path_len);
    path->len = path_len;
  }
  else   {
    /* failed if both 'path' and 'pathExtended' are absent */
    return SC_ERROR_ASN1_OBJECT_NOT_FOUND;
  }

  if (path->len == 2)
    path->type = SC_PATH_TYPE_FILE_ID;
  else   if (path->aid.len && path->len > 2)
    path->type = SC_PATH_TYPE_FROM_CURRENT;
  else
    path->type = SC_PATH_TYPE_PATH;

  if ((asn1_path[1].flags & SC_ASN1_PRESENT) && (asn1_path[2].flags & SC_ASN1_PRESENT)) {
    path->index = idx;
    path->count = count;
  }
  else {
    path->index = 0;
    path->count = -1;
  }

  return SC_SUCCESS;
}

static int asn1_encode_path(sc_context_t *ctx, const sc_path_t *path,
          u8 **buf, size_t *bufsize, int depth, unsigned int parent_flags)
{
  int r;
  struct sc_asn1_entry asn1_path[5];
  sc_path_t tpath = *path;

  sc_copy_asn1_entry(c_asn1_path, asn1_path);
  sc_format_asn1_entry(asn1_path + 0, (void *) &tpath.value, (void *) &tpath.len, 1);

  asn1_path[0].flags |= parent_flags;
  if (path->count > 0) {
    sc_format_asn1_entry(asn1_path + 1, (void *) &tpath.index, NULL, 1);
    sc_format_asn1_entry(asn1_path + 2, (void *) &tpath.count, NULL, 1);
  }
  r = asn1_encode(ctx, asn1_path, buf, bufsize, depth + 1);
  return r;
}


static const struct sc_asn1_entry c_asn1_se[2] = {
  { "seInfo", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, 0, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static const struct sc_asn1_entry c_asn1_se_info[4] = {
  { "se",   SC_ASN1_INTEGER, SC_ASN1_TAG_INTEGER, 0, NULL, NULL },
  { "owner",SC_ASN1_OBJECT, SC_ASN1_TAG_OBJECT, SC_ASN1_OPTIONAL, NULL, NULL },
  { "aid",  SC_ASN1_OCTET_STRING, SC_ASN1_TAG_OCTET_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static int asn1_decode_se_info(sc_context_t *ctx, const u8 *obj, size_t objlen,
             sc_pkcs15_sec_env_info_t ***se, size_t *num, int depth)
{
  struct sc_pkcs15_sec_env_info **ses;
  const unsigned char *ptr = obj;
  size_t idx, ptrlen = objlen;
  int ret;

  LOG_FUNC_CALLED(ctx);

  ses = calloc(SC_MAX_SE_NUM, sizeof(sc_pkcs15_sec_env_info_t *));
  if (ses == NULL) {
    SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_OUT_OF_MEMORY);
  }

  for (idx=0; idx < SC_MAX_SE_NUM && ptrlen; )   {
    struct sc_asn1_entry asn1_se[2];
    struct sc_asn1_entry asn1_se_info[4];
    struct sc_pkcs15_sec_env_info si;

    sc_copy_asn1_entry(c_asn1_se, asn1_se);
    sc_copy_asn1_entry(c_asn1_se_info, asn1_se_info);

    si.aid.len = sizeof(si.aid.value);
    sc_format_asn1_entry(asn1_se_info + 0, &si.se, NULL, 0);
    sc_format_asn1_entry(asn1_se_info + 1, &si.owner, NULL, 0);
    sc_format_asn1_entry(asn1_se_info + 2, &si.aid.value, &si.aid.len, 0);
    sc_format_asn1_entry(asn1_se + 0, asn1_se_info, NULL, 0);

    ret = asn1_decode(ctx, asn1_se, ptr, ptrlen, &ptr, &ptrlen, 0, depth+1);
    if (ret != SC_SUCCESS)
      goto err;
    if (!(asn1_se_info[1].flags & SC_ASN1_PRESENT))
      sc_init_oid(&si.owner);

    ses[idx] = calloc(1, sizeof(sc_pkcs15_sec_env_info_t));
    if (ses[idx] == NULL) {
      ret = SC_ERROR_OUT_OF_MEMORY;
      goto err;
    }

    memcpy(ses[idx], &si, sizeof(struct sc_pkcs15_sec_env_info));
    idx++;
  }

  *se  = ses;
  *num = idx;
  ret = SC_SUCCESS;
err:
  if (ret != SC_SUCCESS) {
    size_t i;
    for (i = 0; i < idx; i++)
      if (ses[i])
        free(ses[i]);
    free(ses);
  }

  SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, ret);
}


static int asn1_encode_se_info(sc_context_t *ctx,
    struct sc_pkcs15_sec_env_info **se, size_t se_num,
    unsigned char **buf, size_t *bufsize, int depth)
{
  unsigned char *ptr = NULL, *out = NULL, *p;
  size_t ptrlen = 0, outlen = 0, idx;
  int ret;

  for (idx=0; idx < se_num; idx++)   {
    struct sc_asn1_entry asn1_se[2];
    struct sc_asn1_entry asn1_se_info[4];

    sc_copy_asn1_entry(c_asn1_se, asn1_se);
    sc_copy_asn1_entry(c_asn1_se_info, asn1_se_info);

    sc_format_asn1_entry(asn1_se_info + 0, &se[idx]->se, NULL, 1);
    if (sc_valid_oid(&se[idx]->owner))
      sc_format_asn1_entry(asn1_se_info + 1, &se[idx]->owner, NULL, 1);
    if (se[idx]->aid.len)
      sc_format_asn1_entry(asn1_se_info + 2, &se[idx]->aid.value, &se[idx]->aid.len, 1);
    sc_format_asn1_entry(asn1_se + 0, asn1_se_info, NULL, 1);

    ret = sc_asn1_encode(ctx, asn1_se, &ptr, &ptrlen);
    if (ret != SC_SUCCESS)
      goto err;

    if (!ptrlen)
      continue;
    p = (unsigned char *) realloc(out, outlen + ptrlen);
    if (!p)   {
      ret = SC_ERROR_OUT_OF_MEMORY;
      goto err;
    }
    out = p;
    memcpy(out + outlen, ptr, ptrlen);
    outlen += ptrlen;
    free(ptr);
    ptr = NULL;
    ptrlen = 0;
  }

  *buf = out;
  *bufsize = outlen;
  ret = SC_SUCCESS;
err:
  if (ret != SC_SUCCESS && out != NULL)
    free(out);
  return ret;
}

/* TODO: According to specification type of 'SecurityCondition' is 'CHOICE'.
 *       Do it at least for SC_ASN1_PKCS15_ID(authId), SC_ASN1_STRUCT(authReference) and NULL(always). */
static const struct sc_asn1_entry c_asn1_access_control_rule[3] = {
  { "accessMode", SC_ASN1_BIT_FIELD, SC_ASN1_TAG_BIT_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { "securityCondition", SC_ASN1_PKCS15_ID, SC_ASN1_TAG_OCTET_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

/*
 * in src/libopensc/pkcs15.h SC_PKCS15_MAX_ACCESS_RULES  defined as 8
 */
static const struct sc_asn1_entry c_asn1_access_control_rules[SC_PKCS15_MAX_ACCESS_RULES + 1] = {
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRule", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static const struct sc_asn1_entry c_asn1_com_obj_attr[6] = {
  { "label", SC_ASN1_UTF8STRING, SC_ASN1_TAG_UTF8STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { "flags", SC_ASN1_BIT_FIELD, SC_ASN1_TAG_BIT_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { "authId", SC_ASN1_PKCS15_ID, SC_ASN1_TAG_OCTET_STRING, SC_ASN1_OPTIONAL, NULL, NULL },
  { "userConsent", SC_ASN1_INTEGER, SC_ASN1_TAG_INTEGER, SC_ASN1_OPTIONAL, NULL, NULL },
  { "accessControlRules", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static const struct sc_asn1_entry c_asn1_p15_obj[5] = {
  { "commonObjectAttributes", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, 0, NULL, NULL },
  { "classAttributes", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, 0, NULL, NULL },
  { "subClassAttributes", SC_ASN1_STRUCT, SC_ASN1_CTX | 0 | SC_ASN1_CONS, SC_ASN1_OPTIONAL, NULL, NULL },
  { "typeAttributes", SC_ASN1_STRUCT, SC_ASN1_CTX | 1 | SC_ASN1_CONS, 0, NULL, NULL },
  { NULL, 0, 0, 0, NULL, NULL }
};

static int asn1_decode_p15_object(sc_context_t *ctx, const u8 *in,
          size_t len, struct sc_asn1_pkcs15_object *obj,
          int depth)
{
  struct sc_pkcs15_object *p15_obj = obj->p15_obj;
  struct sc_asn1_entry asn1_c_attr[6], asn1_p15_obj[5];
  struct sc_asn1_entry asn1_ac_rules[SC_PKCS15_MAX_ACCESS_RULES + 1], asn1_ac_rule[SC_PKCS15_MAX_ACCESS_RULES][3];
  size_t flags_len = sizeof(p15_obj->flags);
  size_t label_len = sizeof(p15_obj->label);
  size_t access_mode_len = sizeof(p15_obj->access_rules[0].access_mode);
  int r, ii;

  for (ii=0; ii<SC_PKCS15_MAX_ACCESS_RULES; ii++)
    sc_copy_asn1_entry(c_asn1_access_control_rule, asn1_ac_rule[ii]);
  sc_copy_asn1_entry(c_asn1_access_control_rules, asn1_ac_rules);


  sc_copy_asn1_entry(c_asn1_com_obj_attr, asn1_c_attr);
  sc_copy_asn1_entry(c_asn1_p15_obj, asn1_p15_obj);
  sc_format_asn1_entry(asn1_c_attr + 0, p15_obj->label, &label_len, 0);
  sc_format_asn1_entry(asn1_c_attr + 1, &p15_obj->flags, &flags_len, 0);
  sc_format_asn1_entry(asn1_c_attr + 2, &p15_obj->auth_id, NULL, 0);
  sc_format_asn1_entry(asn1_c_attr + 3, &p15_obj->user_consent, NULL, 0);

  for (ii=0; ii<SC_PKCS15_MAX_ACCESS_RULES; ii++)   {
    sc_format_asn1_entry(asn1_ac_rule[ii] + 0, &p15_obj->access_rules[ii].access_mode, &access_mode_len, 0);
    sc_format_asn1_entry(asn1_ac_rule[ii] + 1, &p15_obj->access_rules[ii].auth_id, NULL, 0);
    sc_format_asn1_entry(asn1_ac_rules + ii, asn1_ac_rule[ii], NULL, 0);
  }
  sc_format_asn1_entry(asn1_c_attr + 4, asn1_ac_rules, NULL, 0);

  sc_format_asn1_entry(asn1_p15_obj + 0, asn1_c_attr, NULL, 0);
  sc_format_asn1_entry(asn1_p15_obj + 1, obj->asn1_class_attr, NULL, 0);
  sc_format_asn1_entry(asn1_p15_obj + 2, obj->asn1_subclass_attr, NULL, 0);
  sc_format_asn1_entry(asn1_p15_obj + 3, obj->asn1_type_attr, NULL, 0);

  r = asn1_decode(ctx, asn1_p15_obj, in, len, NULL, NULL, 0, depth + 1);
  return r;
}

static int asn1_encode_p15_object(sc_context_t *ctx, const struct sc_asn1_pkcs15_object *obj,
          u8 **buf, size_t *bufsize, int depth)
{
  struct sc_pkcs15_object p15_obj = *obj->p15_obj;
  struct sc_asn1_entry    asn1_c_attr[6], asn1_p15_obj[5];
  struct sc_asn1_entry asn1_ac_rules[SC_PKCS15_MAX_ACCESS_RULES + 1], asn1_ac_rule[SC_PKCS15_MAX_ACCESS_RULES][3];
  size_t label_len = strlen(p15_obj.label);
  size_t flags_len;
  size_t access_mode_len;
  int r, ii;

  sc_debug(ctx, SC_LOG_DEBUG_ASN1, "encode p15 obj(type:0x%X,access_mode:0x%X)", p15_obj.type, p15_obj.access_rules[0].access_mode);
  if (p15_obj.access_rules[0].access_mode)   {
    for (ii=0; ii<SC_PKCS15_MAX_ACCESS_RULES; ii++)   {
      sc_copy_asn1_entry(c_asn1_access_control_rule, asn1_ac_rule[ii]);
      if (p15_obj.access_rules[ii].auth_id.len == 0)   {
        asn1_ac_rule[ii][1].type = SC_ASN1_NULL;
        asn1_ac_rule[ii][1].tag = SC_ASN1_TAG_NULL;
      }
    }
    sc_copy_asn1_entry(c_asn1_access_control_rules, asn1_ac_rules);
  }

  sc_copy_asn1_entry(c_asn1_com_obj_attr, asn1_c_attr);
  sc_copy_asn1_entry(c_asn1_p15_obj, asn1_p15_obj);
  if (label_len != 0)
    sc_format_asn1_entry(asn1_c_attr + 0, (void *) p15_obj.label, &label_len, 1);
  if (p15_obj.flags) {
    flags_len = sizeof(p15_obj.flags);
    sc_format_asn1_entry(asn1_c_attr + 1, (void *) &p15_obj.flags, &flags_len, 1);
  }
  if (p15_obj.auth_id.len)
    sc_format_asn1_entry(asn1_c_attr + 2, (void *) &p15_obj.auth_id, NULL, 1);
  if (p15_obj.user_consent)
    sc_format_asn1_entry(asn1_c_attr + 3, (void *) &p15_obj.user_consent, NULL, 1);

  if (p15_obj.access_rules[0].access_mode)   {
    for (ii=0; p15_obj.access_rules[ii].access_mode; ii++)   {
      access_mode_len = sizeof(p15_obj.access_rules[ii].access_mode);
      sc_format_asn1_entry(asn1_ac_rule[ii] + 0, (void *) &p15_obj.access_rules[ii].access_mode, &access_mode_len, 1);
      sc_format_asn1_entry(asn1_ac_rule[ii] + 1, (void *) &p15_obj.access_rules[ii].auth_id, NULL, 1);
      sc_format_asn1_entry(asn1_ac_rules + ii, asn1_ac_rule[ii], NULL, 1);
    }
    sc_format_asn1_entry(asn1_c_attr + 4, asn1_ac_rules, NULL, 1);
  }

  sc_format_asn1_entry(asn1_p15_obj + 0, asn1_c_attr, NULL, 1);
  sc_format_asn1_entry(asn1_p15_obj + 1, obj->asn1_class_attr, NULL, 1);
  if (obj->asn1_subclass_attr != NULL && obj->asn1_subclass_attr->name)
    sc_format_asn1_entry(asn1_p15_obj + 2, obj->asn1_subclass_attr, NULL, 1);
  sc_format_asn1_entry(asn1_p15_obj + 3, obj->asn1_type_attr, NULL, 1);

  r = asn1_encode(ctx, asn1_p15_obj, buf, bufsize, depth + 1);
  return r;
}

static int asn1_decode_entry(sc_context_t *ctx,struct sc_asn1_entry *entry,
           const u8 *obj, size_t objlen, int depth)
{
  void *parm = entry->parm;
  int (*callback_func)(sc_context_t *nctx, void *arg, const u8 *nobj,
           size_t nobjlen, int ndepth);
  size_t *len = (size_t *) entry->arg;
  int r = 0;

  callback_func = parm;

  sc_debug(ctx, SC_LOG_DEBUG_ASN1, "%*.*sdecoding '%s', raw data:%s%s\n",
    depth, depth, "", entry->name,
    sc_dump_hex(obj, objlen > 16  ? 16 : objlen),
    objlen > 16 ? "..." : "");

  switch (entry->type) {
  case SC_ASN1_STRUCT:
    if (parm != NULL)
      r = asn1_decode(ctx, (struct sc_asn1_entry *) parm, obj,
               objlen, NULL, NULL, 0, depth + 1);
    break;
  case SC_ASN1_NULL:
    break;
  case SC_ASN1_BOOLEAN:
    if (parm != NULL) {
      if (objlen != 1) {
        sc_debug(ctx, SC_LOG_DEBUG_ASN1,
           "invalid ASN.1 object length: %"SC_FORMAT_LEN_SIZE_T"u\n",
           objlen);
        r = SC_ERROR_INVALID_ASN1_OBJECT;
      } else
        *((int *) parm) = obj[0] ? 1 : 0;
    }
    break;
  case SC_ASN1_INTEGER:
  case SC_ASN1_ENUMERATED:
    if (parm != NULL) {
      r = sc_asn1_decode_integer(obj, objlen, (int *) entry->parm, 0);
      sc_debug(ctx, SC_LOG_DEBUG_ASN1, "%*.*sdecoding '%s' returned %d\n", depth, depth, "",
          entry->name, *((int *) entry->parm));
    }
    break;
  case SC_ASN1_BIT_STRING_NI:
  case SC_ASN1_BIT_STRING:
    if (parm != NULL) {
      int invert = entry->type == SC_ASN1_BIT_STRING ? 1 : 0;
      assert(len != NULL);
      if (objlen < 1) {
        r = SC_ERROR_INVALID_ASN1_OBJECT;
        break;
      }
      if (entry->flags & SC_ASN1_ALLOC) {
        u8 **buf = (u8 **) parm;
        if (objlen > 1) {
          *buf = malloc(objlen-1);
          if (*buf == NULL) {
            r = SC_ERROR_OUT_OF_MEMORY;
            break;
          }
        }
        *len = objlen-1;
        parm = *buf;
      }
      r = decode_bit_string(obj, objlen, (u8 *) parm, *len, invert, 0);
      if (r >= 0) {
        *len = r;
        r = 0;
      }
    }
    break;
  case SC_ASN1_BIT_FIELD:
    if (parm != NULL)
      r = decode_bit_field(obj, objlen, (u8 *) parm, *len, 0);
    break;
  case SC_ASN1_OCTET_STRING:
    if (parm != NULL) {
      size_t c;
      assert(len != NULL);

      /* Strip off padding zero */
      if ((entry->flags & SC_ASN1_UNSIGNED)
          && objlen > 1 && obj[0] == 0x00) {
        objlen--;
        obj++;
      }

      /* Allocate buffer if needed */
      if (entry->flags & SC_ASN1_ALLOC) {
        u8 **buf = (u8 **) parm;
        if (objlen > 0) {
          *buf = malloc(objlen);
          if (*buf == NULL) {
            r = SC_ERROR_OUT_OF_MEMORY;
            break;
          }
        }
        c = *len = objlen;
        parm = *buf;
      } else
        c = objlen > *len ? *len : objlen;

      memcpy(parm, obj, c);
      *len = c;
    }
    break;
  case SC_ASN1_GENERALIZEDTIME:
    if (parm != NULL) {
      size_t c;
      assert(len != NULL);
      if (entry->flags & SC_ASN1_ALLOC) {
        u8 **buf = (u8 **) parm;
        if (objlen > 0) {
          *buf = malloc(objlen);
          if (*buf == NULL) {
            r = SC_ERROR_OUT_OF_MEMORY;
            break;
          }
        }
        c = *len = objlen;
        parm = *buf;
      } else
        c = objlen > *len ? *len : objlen;

      memcpy(parm, obj, c);
      *len = c;
    }
    break;
  case SC_ASN1_OBJECT:
    if (parm != NULL)
      r = sc_asn1_decode_object_id(obj, objlen, (struct sc_object_id *) parm);
    break;
  case SC_ASN1_PRINTABLESTRING:
  case SC_ASN1_UTF8STRING:
    if (parm != NULL) {
      assert(len != NULL);
      if (entry->flags & SC_ASN1_ALLOC) {
        u8 **buf = (u8 **) parm;
        *buf = malloc(objlen+1);
        if (*buf == NULL) {
          r = SC_ERROR_OUT_OF_MEMORY;
          break;
        }
        *len = objlen+1;
        parm = *buf;
      }
      r = sc_asn1_decode_utf8string(obj, objlen, (u8 *) parm, len);
      if (entry->flags & SC_ASN1_ALLOC) {
        *len -= 1;
      }
    }
    break;
  case SC_ASN1_PATH:
    if (entry->parm != NULL)
      r = asn1_decode_path(ctx, obj, objlen, (sc_path_t *) parm, depth);
    break;
  case SC_ASN1_PKCS15_ID:
    if (entry->parm != NULL) {
      struct sc_pkcs15_id *id = (struct sc_pkcs15_id *) parm;
      size_t c = objlen > sizeof(id->value) ? sizeof(id->value) : objlen;

      memcpy(id->value, obj, c);
      id->len = c;
    }
    break;
  case SC_ASN1_PKCS15_OBJECT:
    if (entry->parm != NULL)
      r = asn1_decode_p15_object(ctx, obj, objlen, (struct sc_asn1_pkcs15_object *) parm, depth);
    break;
  case SC_ASN1_ALGORITHM_ID:
    if (entry->parm != NULL)
      r = sc_asn1_decode_algorithm_id(ctx, obj, objlen, (struct sc_algorithm_id *) parm, depth);
    break;
  case SC_ASN1_SE_INFO:
    if (entry->parm != NULL)
      r = asn1_decode_se_info(ctx, obj, objlen, (sc_pkcs15_sec_env_info_t ***)entry->parm, len, depth);
    break;
  case SC_ASN1_CALLBACK:
    if (entry->parm != NULL)
      r = callback_func(ctx, entry->arg, obj, objlen, depth);
    break;
  default:
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "invalid ASN.1 type: %d\n", entry->type);
    return SC_ERROR_INVALID_ASN1_OBJECT;
  }
  if (r) {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "decoding of ASN.1 object '%s' failed: %s\n", entry->name,
          sc_strerror(r));
    return r;
  }
  entry->flags |= SC_ASN1_PRESENT;
  return 0;
}

static void sc_free_entry(struct sc_asn1_entry *asn1) {
  int idx = 0;
  struct sc_asn1_entry *entry = asn1;

  if (!asn1)
    return;

  for (idx = 0; asn1[idx].name != NULL; idx++) {
    entry = &asn1[idx];
    switch (entry->type) {
    case SC_ASN1_CHOICE:
    case SC_ASN1_STRUCT:
      sc_free_entry((struct sc_asn1_entry *) entry->parm);
      break;
    case SC_ASN1_OCTET_STRING:
    case SC_ASN1_BIT_STRING_NI:
    case SC_ASN1_BIT_STRING:
    case SC_ASN1_GENERALIZEDTIME:
    case SC_ASN1_PRINTABLESTRING:
    case SC_ASN1_UTF8STRING:
      if ((entry->flags & SC_ASN1_ALLOC) && (entry->flags & SC_ASN1_PRESENT)) {
        u8 **buf = (u8 **)entry->parm;
        free(*buf);
        *buf = NULL;
      }
      break;
    default:
      break;
    }
  }
}

static int asn1_decode(sc_context_t *ctx, struct sc_asn1_entry *asn1,
           const u8 *in, size_t len, const u8 **newp, size_t *len_left,
           int choice, int depth)
{
  int r, idx = 0;
  const u8 *p = in, *obj;
  struct sc_asn1_entry *entry = asn1;
  size_t left = len, objlen;

  sc_debug(ctx, SC_LOG_DEBUG_ASN1,
     "%*.*s""called, left=%"SC_FORMAT_LEN_SIZE_T"u, depth %d%s\n",
     depth, depth, "", left, depth, choice ? ", choice" : "");

  if (!p)
    return SC_ERROR_ASN1_OBJECT_NOT_FOUND;
  if (left < 2) {
    while (asn1->name && (asn1->flags & SC_ASN1_OPTIONAL))
      asn1++;
    /* If all elements were optional, there's nothing
     * to complain about */
    if (asn1->name == NULL)
      return 0;
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "End of ASN.1 stream, "
            "non-optional field \"%s\" not found\n",
            asn1->name);
    return SC_ERROR_ASN1_OBJECT_NOT_FOUND;
  }
  if (p[0] == 0 || p[0] == 0xFF || len == 0)
    return SC_ERROR_ASN1_END_OF_CONTENTS;

  for (idx = 0; asn1[idx].name != NULL; idx++) {
    entry = &asn1[idx];

    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "Looking for '%s', tag 0x%x%s%s\n",
      entry->name, entry->tag, choice? ", CHOICE" : "",
      (entry->flags & SC_ASN1_OPTIONAL)? ", OPTIONAL": "");

    /* Special case CHOICE has no tag */
    if (entry->type == SC_ASN1_CHOICE) {
      r = asn1_decode(ctx,
        (struct sc_asn1_entry *) entry->parm,
        p, left, &p, &left, 1, depth + 1);
      if (r >= 0)
        r = 0;
      goto decode_ok;
    }

    obj = sc_asn1_skip_tag(ctx, &p, &left, entry->tag, &objlen);
    if (obj == NULL) {
      sc_debug(ctx, SC_LOG_DEBUG_ASN1, "'%s' not present\n", entry->name);
      if (choice)
        continue;
      if (entry->flags & SC_ASN1_OPTIONAL)
        continue;
      sc_debug(ctx, SC_LOG_DEBUG_ASN1, "mandatory ASN.1 object '%s' not found\n", entry->name);
      if (left) {
        u8 line[128], *linep = line;
        size_t i;

        line[0] = 0;
        for (i = 0; i < 10 && i < left; i++) {
          sprintf((char *) linep, "%02X ", p[i]);
          linep += 3;
        }
        sc_debug(ctx, SC_LOG_DEBUG_ASN1, "next tag: %s\n", line);
      }
      sc_free_entry(asn1);
      SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_ASN1_OBJECT_NOT_FOUND);
    }
    r = asn1_decode_entry(ctx, entry, obj, objlen, depth);

decode_ok:
    if (r)
      return r;
    if (choice)
      break;
  }
  if (choice && asn1[idx].name == NULL) /* No match */
    SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, SC_ERROR_ASN1_OBJECT_NOT_FOUND);
  if (newp != NULL)
    *newp = p;
  if (len_left != NULL)
    *len_left = left;
  if (choice)
    SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, idx);
  SC_FUNC_RETURN(ctx, SC_LOG_DEBUG_ASN1, 0);
}

int sc_asn1_decode(sc_context_t *ctx, struct sc_asn1_entry *asn1,
       const u8 *in, size_t len, const u8 **newp, size_t *len_left)
{
  return asn1_decode(ctx, asn1, in, len, newp, len_left, 0, 0);
}

int sc_asn1_decode_choice(sc_context_t *ctx, struct sc_asn1_entry *asn1,
        const u8 *in, size_t len, const u8 **newp, size_t *len_left)
{
  return asn1_decode(ctx, asn1, in, len, newp, len_left, 1, 0);
}

static int asn1_encode_entry(sc_context_t *ctx, const struct sc_asn1_entry *entry,
           u8 **obj, size_t *objlen, int depth)
{
  void *parm = entry->parm;
  int (*callback_func)(sc_context_t *nctx, void *arg, u8 **nobj,
           size_t *nobjlen, int ndepth);
  const size_t *len = (const size_t *) entry->arg;
  int r = 0;
  u8 * buf = NULL;
  size_t buflen = 0;

  callback_func = parm;

  sc_debug(ctx, SC_LOG_DEBUG_ASN1, "%*.*sencoding '%s'%s\n",
          depth, depth, "", entry->name,
    (entry->flags & SC_ASN1_PRESENT)? "" : " (not present)");
  if (!(entry->flags & SC_ASN1_PRESENT))
    goto no_object;
  sc_debug(ctx, SC_LOG_DEBUG_ASN1,
     "%*.*stype=%d, tag=0x%02x, parm=%p, len=%"SC_FORMAT_LEN_SIZE_T"u\n",
     depth, depth, "", entry->type, entry->tag, parm,
     len ? *len : 0);

  if (entry->type == SC_ASN1_CHOICE) {
    const struct sc_asn1_entry *list, *choice = NULL;

    list = (const struct sc_asn1_entry *) parm;
    while (list->name != NULL) {
      if (list->flags & SC_ASN1_PRESENT) {
        if (choice) {
          sc_debug(ctx, SC_LOG_DEBUG_ASN1,
            "ASN.1 problem: more than "
            "one CHOICE when encoding %s: "
            "%s and %s both present\n",
            entry->name,
            choice->name,
            list->name);
          return SC_ERROR_INVALID_ASN1_OBJECT;
        }
        choice = list;
      }
      list++;
    }
    if (choice == NULL)
      goto no_object;
    return asn1_encode_entry(ctx, choice, obj, objlen, depth + 1);
  }

  if (entry->type != SC_ASN1_NULL && parm == NULL) {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "unexpected parm == NULL\n");
    return SC_ERROR_INVALID_ASN1_OBJECT;
  }

  switch (entry->type) {
  case SC_ASN1_STRUCT:
    r = asn1_encode(ctx, (const struct sc_asn1_entry *) parm, &buf,
        &buflen, depth + 1);
    break;
  case SC_ASN1_NULL:
    buf = NULL;
    buflen = 0;
    break;
  case SC_ASN1_BOOLEAN:
    buf = malloc(1);
    if (buf == NULL) {
      r = SC_ERROR_OUT_OF_MEMORY;
      break;
    }
    buf[0] = *((int *) parm) ? 0xFF : 0;
    buflen = 1;
    break;
  case SC_ASN1_INTEGER:
  case SC_ASN1_ENUMERATED:
    r = asn1_encode_integer(*((int *) entry->parm), &buf, &buflen);
    break;
  case SC_ASN1_BIT_STRING_NI:
  case SC_ASN1_BIT_STRING:
    if (len != NULL) {
      if (entry->type == SC_ASN1_BIT_STRING)
        r = encode_bit_string((const u8 *) parm, *len, &buf, &buflen, 1);
      else
        r = encode_bit_string((const u8 *) parm, *len, &buf, &buflen, 0);
    } else {
      r = SC_ERROR_INVALID_ARGUMENTS;
    }
    break;
  case SC_ASN1_BIT_FIELD:
    if (len != NULL) {
      r = encode_bit_field((const u8 *) parm, *len, &buf, &buflen);
    } else {
      r = SC_ERROR_INVALID_ARGUMENTS;
    }
    break;
  case SC_ASN1_PRINTABLESTRING:
  case SC_ASN1_OCTET_STRING:
  case SC_ASN1_UTF8STRING:
    if (len != NULL) {
      buf = malloc(*len + 1);
      if (buf == NULL) {
        r = SC_ERROR_OUT_OF_MEMORY;
        break;
      }
      buflen = 0;
      /* If the integer is supposed to be unsigned, insert
       * a padding byte if the MSB is one */
      if ((entry->flags & SC_ASN1_UNSIGNED)
          && (((u8 *) parm)[0] & 0x80)) {
        buf[buflen++] = 0x00;
      }
      memcpy(buf + buflen, parm, *len);
      buflen += *len;
    } else {
      r = SC_ERROR_INVALID_ARGUMENTS;
    }
    break;
  case SC_ASN1_GENERALIZEDTIME:
    if (len != NULL) {
      buf = malloc(*len);
      if (buf == NULL) {
        r = SC_ERROR_OUT_OF_MEMORY;
        break;
      }
      memcpy(buf, parm, *len);
      buflen = *len;
    } else {
      r = SC_ERROR_INVALID_ARGUMENTS;
    }
    break;
  case SC_ASN1_OBJECT:
    r = sc_asn1_encode_object_id(&buf, &buflen, (struct sc_object_id *) parm);
    break;
  case SC_ASN1_PATH:
    r = asn1_encode_path(ctx, (const sc_path_t *) parm, &buf, &buflen, depth, entry->flags);
    break;
  case SC_ASN1_PKCS15_ID:
    {
      const struct sc_pkcs15_id *id = (const struct sc_pkcs15_id *) parm;

      buf = malloc(id->len);
      if (buf == NULL) {
        r = SC_ERROR_OUT_OF_MEMORY;
        break;
      }
      memcpy(buf, id->value, id->len);
      buflen = id->len;
    }
    break;
  case SC_ASN1_PKCS15_OBJECT:
    r = asn1_encode_p15_object(ctx, (const struct sc_asn1_pkcs15_object *) parm, &buf, &buflen, depth);
    break;
  case SC_ASN1_ALGORITHM_ID:
    r = sc_asn1_encode_algorithm_id(ctx, &buf, &buflen, (const struct sc_algorithm_id *) parm, depth);
    break;
  case SC_ASN1_SE_INFO:
    if (!len)
      return SC_ERROR_INVALID_ASN1_OBJECT;
    r = asn1_encode_se_info(ctx, (struct sc_pkcs15_sec_env_info **)parm, *len, &buf, &buflen, depth);
    break;
  case SC_ASN1_CALLBACK:
    r = callback_func(ctx, entry->arg, &buf, &buflen, depth);
    break;
  default:
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "invalid ASN.1 type: %d\n", entry->type);
    return SC_ERROR_INVALID_ASN1_OBJECT;
  }
  if (r) {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "encoding of ASN.1 object '%s' failed: %s\n", entry->name,
          sc_strerror(r));
    if (buf)
      free(buf);
    return r;
  }

  /* Treatment of OPTIONAL elements:
   *  - if the encoding has 0 length, and the element is OPTIONAL,
   *  we don't write anything (unless it's an ASN1 NULL and the
   *      SC_ASN1_PRESENT flag is set).
   *  - if the encoding has 0 length, but the element is non-OPTIONAL,
   *  constructed, we write a empty element (e.g. a SEQUENCE of
   *      length 0). In case of an ASN1 NULL just write the tag and
   *      length (i.e. 0x05,0x00).
   *  - any other empty objects are considered bogus
   */
no_object:
  if (!buflen && entry->flags & SC_ASN1_OPTIONAL && !(entry->flags & SC_ASN1_PRESENT)) {
    /* This happens when we try to encode e.g. the
     * subClassAttributes, which may be empty */
    *obj = NULL;
    *objlen = 0;
    r = 0;
  } else if (!buflen && (entry->flags & SC_ASN1_EMPTY_ALLOWED)) {
    *obj = NULL;
    *objlen = 0;
    r = asn1_write_element(ctx, entry->tag, buf, buflen, obj, objlen);
    if (r)
      sc_debug(ctx, SC_LOG_DEBUG_ASN1, "error writing ASN.1 tag and length: %s\n", sc_strerror(r));
  } else if (buflen || entry->type == SC_ASN1_NULL || entry->tag & SC_ASN1_CONS) {
    r = asn1_write_element(ctx, entry->tag, buf, buflen, obj, objlen);
    if (r)
      sc_debug(ctx, SC_LOG_DEBUG_ASN1, "error writing ASN.1 tag and length: %s\n",
          sc_strerror(r));
  } else if (!(entry->flags & SC_ASN1_PRESENT)) {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "cannot encode non-optional ASN.1 object: not given by caller\n");
    r = SC_ERROR_INVALID_ASN1_OBJECT;
  } else {
    sc_debug(ctx, SC_LOG_DEBUG_ASN1, "cannot encode empty non-optional ASN.1 object\n");
    r = SC_ERROR_INVALID_ASN1_OBJECT;
  }
  if (buf)
    free(buf);
  if (r >= 0)
    sc_debug(ctx, SC_LOG_DEBUG_ASN1,
       "%*.*slength of encoded item=%"SC_FORMAT_LEN_SIZE_T"u\n",
       depth, depth, "", *objlen);
  return r;
}

static int asn1_encode(sc_context_t *ctx, const struct sc_asn1_entry *asn1,
          u8 **ptr, size_t *size, int depth)
{
  int r, idx = 0;
  u8 *obj = NULL, *buf = NULL, *tmp;
  size_t total = 0, objsize;

  if (asn1 == NULL) {
    return SC_ERROR_INVALID_ARGUMENTS;
  }

  for (idx = 0; asn1[idx].name != NULL; idx++) {
    r = asn1_encode_entry(ctx, &asn1[idx], &obj, &objsize, depth);
    if (r) {
      if (obj)
        free(obj);
      if (buf)
        free(buf);
      return r;
    }
    /* in case of an empty (optional) element continue with
     * the next asn1 element */
    if (!objsize)
      continue;
    tmp = (u8 *) realloc(buf, total + objsize);
    if (!tmp) {
      if (obj)
        free(obj);
      if (buf)
        free(buf);
      return SC_ERROR_OUT_OF_MEMORY;
    }
    buf = tmp;
    memcpy(buf + total, obj, objsize);
    free(obj);
    obj = NULL;
    total += objsize;
  }
  *ptr = buf;
  *size = total;
  return 0;
}

int sc_asn1_encode(sc_context_t *ctx, const struct sc_asn1_entry *asn1,
       u8 **ptr, size_t *size)
{
  return asn1_encode(ctx, asn1, ptr, size, 0);
}

int _sc_asn1_encode(sc_context_t *ctx, const struct sc_asn1_entry *asn1,
        u8 **ptr, size_t *size, int depth)
{
  return asn1_encode(ctx, asn1, ptr, size, depth);
}

int
_sc_asn1_decode(sc_context_t *ctx, struct sc_asn1_entry *asn1,
           const u8 *in, size_t len, const u8 **newp, size_t *left,
           int choice, int depth)
{
  return asn1_decode(ctx, asn1, in, len, newp, left, choice, depth);
}

int
sc_der_copy(sc_pkcs15_der_t *dst, const sc_pkcs15_der_t *src)
{
  if (!dst || !src)
    return SC_ERROR_INVALID_ARGUMENTS;
  memset(dst, 0, sizeof(*dst));
  if (src->len) {
    if (!src->value)
      return SC_ERROR_INVALID_ARGUMENTS;
    dst->value = malloc(src->len);
    if (!dst->value)
      return SC_ERROR_OUT_OF_MEMORY;
    dst->len = src->len;
    memcpy(dst->value, src->value, src->len);
  }
  return SC_SUCCESS;
}

int
sc_encode_oid (struct sc_context *ctx, struct sc_object_id *id,
    unsigned char **out, size_t *size)
{
  static const struct sc_asn1_entry c_asn1_object_id[2] = {
    { "oid", SC_ASN1_OBJECT, SC_ASN1_TAG_OBJECT, SC_ASN1_ALLOC, NULL, NULL },
    { NULL, 0, 0, 0, NULL, NULL }
  };
  struct sc_asn1_entry asn1_object_id[2];
  int rv;

  sc_copy_asn1_entry(c_asn1_object_id, asn1_object_id);
  sc_format_asn1_entry(asn1_object_id + 0, id, NULL, 1);

  rv = _sc_asn1_encode(ctx, asn1_object_id, out, size, 1);
  LOG_TEST_RET(ctx, rv, "Cannot encode object ID");

  return SC_SUCCESS;
}


#define C_ASN1_SIG_VALUE_SIZE 2
static struct sc_asn1_entry c_asn1_sig_value[C_ASN1_SIG_VALUE_SIZE] = {
    { "ECDSA-Sig-Value", SC_ASN1_STRUCT, SC_ASN1_TAG_SEQUENCE | SC_ASN1_CONS, 0, NULL, NULL },
    { NULL, 0, 0, 0, NULL, NULL }
};

#define C_ASN1_SIG_VALUE_COEFFICIENTS_SIZE 3
static struct sc_asn1_entry c_asn1_sig_value_coefficients[C_ASN1_SIG_VALUE_COEFFICIENTS_SIZE] = {
    { "r", SC_ASN1_OCTET_STRING, SC_ASN1_TAG_INTEGER, SC_ASN1_ALLOC|SC_ASN1_UNSIGNED, NULL, NULL },
    { "s", SC_ASN1_OCTET_STRING, SC_ASN1_TAG_INTEGER, SC_ASN1_ALLOC|SC_ASN1_UNSIGNED, NULL, NULL },
    { NULL, 0, 0, 0, NULL, NULL }
};


int
sc_asn1_sig_value_rs_to_sequence(struct sc_context *ctx, unsigned char *in, size_t inlen,
    unsigned char **buf, size_t *buflen)
{
  struct sc_asn1_entry asn1_sig_value[C_ASN1_SIG_VALUE_SIZE];
  struct sc_asn1_entry asn1_sig_value_coefficients[C_ASN1_SIG_VALUE_COEFFICIENTS_SIZE];
  unsigned char *r = in, *s = in + inlen/2;
  size_t r_len = inlen/2, s_len = inlen/2;
  int rv;

  LOG_FUNC_CALLED(ctx);

  /* R/S are filled up with zeroes, we do not want that in sequence format */
  while(r_len > 1 && *r == 0x00) {
    r++;
    r_len--;
  }
  while(s_len > 1 && *s == 0x00) {
    s++;
    s_len--;
  }

  sc_copy_asn1_entry(c_asn1_sig_value, asn1_sig_value);
  sc_format_asn1_entry(asn1_sig_value + 0, asn1_sig_value_coefficients, NULL, 1);

  sc_copy_asn1_entry(c_asn1_sig_value_coefficients, asn1_sig_value_coefficients);
  sc_format_asn1_entry(asn1_sig_value_coefficients + 0, r, &r_len, 1);
  sc_format_asn1_entry(asn1_sig_value_coefficients + 1, s, &s_len, 1);

  rv = sc_asn1_encode(ctx, asn1_sig_value, buf, buflen);
  LOG_TEST_RET(ctx, rv, "ASN.1 encoding ECDSA-SIg-Value failed");

  LOG_FUNC_RETURN(ctx, SC_SUCCESS);
}


int
sc_asn1_sig_value_sequence_to_rs(struct sc_context *ctx, const unsigned char *in, size_t inlen,
    unsigned char *buf, size_t buflen)
{
  struct sc_asn1_entry asn1_sig_value[C_ASN1_SIG_VALUE_SIZE];
  struct sc_asn1_entry asn1_sig_value_coefficients[C_ASN1_SIG_VALUE_COEFFICIENTS_SIZE];
  unsigned char *r = NULL, *s = NULL;
  size_t r_len = 0, s_len = 0, halflen = buflen/2;
  int rv;

  LOG_FUNC_CALLED(ctx);
  if (!buf || !buflen)
    LOG_FUNC_RETURN(ctx, SC_ERROR_INVALID_ARGUMENTS);

  sc_copy_asn1_entry(c_asn1_sig_value, asn1_sig_value);
  sc_format_asn1_entry(asn1_sig_value + 0, asn1_sig_value_coefficients, NULL, 0);

  sc_copy_asn1_entry(c_asn1_sig_value_coefficients, asn1_sig_value_coefficients);
  sc_format_asn1_entry(asn1_sig_value_coefficients + 0, &r, &r_len, 0);
  sc_format_asn1_entry(asn1_sig_value_coefficients + 1, &s, &s_len, 0);

  rv = sc_asn1_decode(ctx, asn1_sig_value, in, inlen, NULL, NULL);
  LOG_TEST_GOTO_ERR(ctx, rv, "ASN.1 decoding ECDSA-Sig-Value failed");

  if (halflen < r_len || halflen < s_len)   {
    rv = SC_ERROR_BUFFER_TOO_SMALL;
    goto err;
  }

  memset(buf, 0, buflen);
  if (r_len > 0)
    memcpy(buf + (halflen - r_len), r, r_len);
  if (s_len > 0)
    memcpy(buf + (buflen - s_len), s, s_len);

  sc_log(ctx, "r(%"SC_FORMAT_LEN_SIZE_T"u): %s", halflen,
         sc_dump_hex(buf, halflen));
  sc_log(ctx, "s(%"SC_FORMAT_LEN_SIZE_T"u): %s", halflen,
         sc_dump_hex(buf + halflen, halflen));

  rv = SC_SUCCESS;
err:
  free(r);
  free(s);

  LOG_FUNC_RETURN(ctx, rv);
}

int sc_asn1_decode_ecdsa_signature(sc_context_t *ctx, const u8 *data, size_t datalen, size_t fieldsize, u8 **out, size_t outlen) {
  int i, r;
  const unsigned char *pseq, *pint, *pend;
  unsigned int cla, tag;
  size_t seqlen, intlen;

  if (!ctx || !data || !out || !(*out)) {
    LOG_FUNC_RETURN(ctx, SC_ERROR_INVALID_ARGUMENTS);
  }
  if (outlen < 2 * fieldsize) {
    LOG_TEST_RET(ctx, SC_ERROR_INVALID_DATA, "Output too small for EC signature");
  }

  memset(*out, 0, outlen);

  pseq = data;
  r = sc_asn1_read_tag(&pseq, datalen, &cla, &tag, &seqlen);
  if (pseq == NULL || r < 0 || seqlen == 0 || (cla | tag) != 0x30)
    LOG_TEST_RET(ctx, SC_ERROR_INVALID_DATA, "Can not find 0x30 tag");

  pint = pseq;
  pend = pseq + seqlen;
  for (i = 0; i < 2; i++) {
    r = sc_asn1_read_tag(&pint, (pend - pint), &cla, &tag, &intlen);
    if (pint == NULL || r < 0 || intlen == 0 || (cla | tag) != 0x02) {
      r = SC_ERROR_INVALID_DATA;
      LOG_TEST_GOTO_ERR(ctx, SC_ERROR_INVALID_DATA, "Can not find 0x02");
    }

    if (intlen == fieldsize + 1) { /* drop leading 00 if present */
      if (*pint != 0x00) {
        r = SC_ERROR_INVALID_DATA;
        LOG_TEST_GOTO_ERR(ctx, SC_ERROR_INVALID_DATA, "Signature too long");
      }
      pint++;
      intlen--;
    }
    if (intlen > fieldsize) {
      r = SC_ERROR_INVALID_DATA;
      LOG_TEST_GOTO_ERR(ctx, SC_ERROR_INVALID_DATA, "Signature too long");
    }
    memcpy(*out + fieldsize * i + fieldsize - intlen , pint, intlen);
    pint += intlen; /* next integer */
  }
  r = (int)(2 * fieldsize);
err:
  LOG_FUNC_RETURN(ctx, r);
}


Coverage Report

Created: 2025-07-11 06:59