/*  $OpenBSD: hkdf_evp.c,v 1.18 2022/05/05 19:48:06 tb Exp $ */

/* ====================================================================

 * Copyright (c) 2016-2018 The OpenSSL Project.  All rights reserved.

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 *    "This product includes software developed by the OpenSSL Project

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 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

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#include <stdlib.h>

#include <string.h>

#include <openssl/err.h>

#include <openssl/evp.h>

#include <openssl/hmac.h>

#include <openssl/hkdf.h>

#include <openssl/kdf.h>

#include "evp_locl.h"

#define HKDF_MAXBUF 1024

typedef struct {

  int mode;

  const EVP_MD *md;

  unsigned char *salt;

  size_t salt_len;

  unsigned char *key;

  size_t key_len;

  unsigned char info[HKDF_MAXBUF];

  size_t info_len;

} HKDF_PKEY_CTX;

static int

pkey_hkdf_init(EVP_PKEY_CTX *ctx)

{

  HKDF_PKEY_CTX *kctx;

  if ((kctx = calloc(1, sizeof(*kctx))) == NULL) {

    KDFerror(ERR_R_MALLOC_FAILURE);

    return 0;

  }

  ctx->data = kctx;

  return 1;

}

static void

pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx)

{

  HKDF_PKEY_CTX *kctx = ctx->data;

  freezero(kctx->salt, kctx->salt_len);

  freezero(kctx->key, kctx->key_len);

  freezero(kctx, sizeof(*kctx));

}

static int

pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)

{

  HKDF_PKEY_CTX *kctx = ctx->data;

  switch (type) {

  case EVP_PKEY_CTRL_HKDF_MD:

    if (p2 == NULL)

      return 0;

    kctx->md = p2;

    return 1;

  case EVP_PKEY_CTRL_HKDF_MODE:

    kctx->mode = p1;

    return 1;

  case EVP_PKEY_CTRL_HKDF_SALT:

    if (p1 == 0 || p2 == NULL)

      return 1;

    if (p1 < 0)

      return 0;

    freezero(kctx->salt, kctx->salt_len);

    if ((kctx->salt = malloc(p1)) == NULL)

      return 0;

    memcpy(kctx->salt, p2, p1);

    kctx->salt_len = p1;

    return 1;

  case EVP_PKEY_CTRL_HKDF_KEY:

    if (p1 <= 0)

      return 0;

    freezero(kctx->key, kctx->key_len);

    if ((kctx->key = malloc(p1)) == NULL)

      return 0;

    memcpy(kctx->key, p2, p1);

    kctx->key_len = p1;

    return 1;

  case EVP_PKEY_CTRL_HKDF_INFO:

    if (p1 == 0 || p2 == NULL)

      return 1;

    if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len))

      return 0;

    memcpy(kctx->info + kctx->info_len, p2, p1);

    kctx->info_len += p1;

    return 1;

  default:

    return -2;

  }

}

static int

pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,

    const char *value)

{

  if (strcmp(type, "mode") == 0) {

    int mode;

    if (strcmp(value, "EXTRACT_AND_EXPAND") == 0)

      mode = EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND;

    else if (strcmp(value, "EXTRACT_ONLY") == 0)

      mode = EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY;

    else if (strcmp(value, "EXPAND_ONLY") == 0)

      mode = EVP_PKEY_HKDEF_MODE_EXPAND_ONLY;

    else

      return 0;

    return EVP_PKEY_CTX_hkdf_mode(ctx, mode);

  }

  if (strcmp(type, "md") == 0)

    return EVP_PKEY_CTX_md(ctx, EVP_PKEY_OP_DERIVE,

        EVP_PKEY_CTRL_HKDF_MD, value);

  if (strcmp(type, "salt") == 0)

    return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT,

        value);

  if (strcmp(type, "hexsalt") == 0)

    return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT,

        value);

  if (strcmp(type, "key") == 0)

    return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);

  if (strcmp(type, "hexkey") == 0)

    return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);

  if (strcmp(type, "info") == 0)

    return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO,

        value);

  if (strcmp(type, "hexinfo") == 0)

    return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO,

        value);

  KDFerror(KDF_R_UNKNOWN_PARAMETER_TYPE);

  return -2;

}

static int

pkey_hkdf_derive_init(EVP_PKEY_CTX *ctx)

{

  HKDF_PKEY_CTX *kctx = ctx->data;

  freezero(kctx->key, kctx->key_len);

  freezero(kctx->salt, kctx->salt_len);

  explicit_bzero(kctx, sizeof(*kctx));

  return 1;

}

static int

pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key,

    size_t *keylen)

{

  HKDF_PKEY_CTX *kctx = ctx->data;

  if (kctx->md == NULL) {

    KDFerror(KDF_R_MISSING_MESSAGE_DIGEST);

    return 0;

  }

  if (kctx->key == NULL) {

    KDFerror(KDF_R_MISSING_KEY);

    return 0;

  }

  switch (kctx->mode) {

  case EVP_PKEY_HKDEF_MODE_EXTRACT_AND_EXPAND:

    return HKDF(key, *keylen, kctx->md, kctx->key, kctx->key_len,

        kctx->salt, kctx->salt_len, kctx->info, kctx->info_len);

  case EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY:

    if (key == NULL) {

      *keylen = EVP_MD_size(kctx->md);

      return 1;

    }

    return HKDF_extract(key, keylen, kctx->md, kctx->key,

        kctx->key_len, kctx->salt, kctx->salt_len);

  case EVP_PKEY_HKDEF_MODE_EXPAND_ONLY:

    return HKDF_expand(key, *keylen, kctx->md, kctx->key,

        kctx->key_len, kctx->info, kctx->info_len);

  default:

    return 0;

  }

}

const EVP_PKEY_METHOD hkdf_pkey_meth = {

  .pkey_id = EVP_PKEY_HKDF,

  .flags = 0,

  .init = pkey_hkdf_init,

  .copy = NULL,

  .cleanup = pkey_hkdf_cleanup,

  .derive_init = pkey_hkdf_derive_init,

  .derive = pkey_hkdf_derive,

  .ctrl = pkey_hkdf_ctrl,

  .ctrl_str = pkey_hkdf_ctrl_str,

};