/*

 * Dropbear - a SSH2 server

 * 

 * Copyright (c) 2002,2003 Matt Johnston

 * All rights reserved.

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 * 

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE. */

/* Perform Ed25519 operations on data, including reading keys, signing and

 * verification. */

#include "includes.h"

#include "dbutil.h"

#include "buffer.h"

#include "ssh.h"

#include "curve25519.h"

#include "ed25519.h"

#if DROPBEAR_ED25519

/* Load a public ed25519 key from a buffer, initialising the values.

 * The key will have the same format as buf_put_ed25519_key.

 * These should be freed with ed25519_key_free.

 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */

int buf_get_ed25519_pub_key(buffer *buf, dropbear_ed25519_key *key,

  enum signkey_type expect_keytype) {

  unsigned int len, typelen;

  char *keytype = NULL;

  enum signkey_type buf_keytype;

  TRACE(("enter buf_get_ed25519_pub_key"))

  dropbear_assert(key != NULL);

  /* consume and check the key string */

  keytype = buf_getstring(buf, &typelen);

  buf_keytype = signkey_type_from_name(keytype, typelen);

  m_free(keytype);

  if (buf_keytype != expect_keytype) {

    TRACE(("leave buf_get_ed25519_pub_key: mismatch key type"))

    return DROPBEAR_FAILURE;

  }

  len = buf_getint(buf);

  if (len != CURVE25519_LEN || buf->len - buf->pos < len) {

    TRACE(("leave buf_get_ed25519_pub_key: failure"))

    return DROPBEAR_FAILURE;

  }

  m_burn(key->priv, CURVE25519_LEN);

  memcpy(key->pub, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);

  buf_incrpos(buf, CURVE25519_LEN);

  TRACE(("leave buf_get_ed25519_pub_key: success"))

  return DROPBEAR_SUCCESS;

}

/* Same as buf_get_ed25519_pub_key, but reads private key at the end.

 * Loads a public and private ed25519 key from a buffer

 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */

int buf_get_ed25519_priv_key(buffer *buf, dropbear_ed25519_key *key) {

  unsigned int len;

  TRACE(("enter buf_get_ed25519_priv_key"))

  dropbear_assert(key != NULL);

  buf_incrpos(buf, 4+SSH_SIGNKEY_ED25519_LEN); /* int + "ssh-ed25519" */

  len = buf_getint(buf);

  if (len != CURVE25519_LEN*2 || buf->len - buf->pos < len) {

    TRACE(("leave buf_get_ed25519_priv_key: failure"))

    return DROPBEAR_FAILURE;

  }

  memcpy(key->priv, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);

  buf_incrpos(buf, CURVE25519_LEN);

  memcpy(key->pub, buf_getptr(buf, CURVE25519_LEN), CURVE25519_LEN);

  buf_incrpos(buf, CURVE25519_LEN);

  TRACE(("leave buf_get_ed25519_priv_key: success"))

  return DROPBEAR_SUCCESS;

}

/* Clear and free the memory used by a public or private key */

void ed25519_key_free(dropbear_ed25519_key *key) {

  TRACE2(("enter ed25519_key_free"))

  if (key == NULL) {

    TRACE2(("leave ed25519_key_free: key == NULL"))

    return;

  }

  m_burn(key->priv, CURVE25519_LEN);

  m_free(key);

  TRACE2(("leave ed25519_key_free"))

}

/* Put the public ed25519 key into the buffer in the required format */

void buf_put_ed25519_pub_key(buffer *buf, const dropbear_ed25519_key *key) {

  TRACE(("enter buf_put_ed25519_pub_key"))

  dropbear_assert(key != NULL);

  buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);

  buf_putstring(buf, key->pub, CURVE25519_LEN);

  TRACE(("leave buf_put_ed25519_pub_key"))

}

/* Put the public and private ed25519 key into the buffer in the required format */

void buf_put_ed25519_priv_key(buffer *buf, const dropbear_ed25519_key *key) {

  TRACE(("enter buf_put_ed25519_priv_key"))

  dropbear_assert(key != NULL);

  buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);

  buf_putint(buf, CURVE25519_LEN*2);

  buf_putbytes(buf, key->priv, CURVE25519_LEN);

  buf_putbytes(buf, key->pub, CURVE25519_LEN);

  TRACE(("leave buf_put_ed25519_priv_key"))

}

/* Sign the data presented with key, writing the signature contents

 * to the buffer */

void buf_put_ed25519_sign(buffer* buf, const dropbear_ed25519_key *key, const buffer *data_buf) {

  unsigned char s[64];

  unsigned long slen = sizeof(s);

  TRACE(("enter buf_put_ed25519_sign"))

  dropbear_assert(key != NULL);

  dropbear_ed25519_sign(data_buf->data, data_buf->len, s, &slen, key->priv, key->pub);

  buf_putstring(buf, SSH_SIGNKEY_ED25519, SSH_SIGNKEY_ED25519_LEN);

  buf_putstring(buf, s, slen);

  TRACE(("leave buf_put_ed25519_sign"))

}

#if DROPBEAR_SIGNKEY_VERIFY

/* Verify a signature in buf, made on data by the key given.

 * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */

int buf_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const buffer *data_buf) {

  int ret = DROPBEAR_FAILURE;

  unsigned char *s;

  unsigned long slen;

  TRACE(("enter buf_ed25519_verify"))

  dropbear_assert(key != NULL);

  slen = buf_getint(buf);

  if (slen != 64 || buf->len - buf->pos < slen) {

    TRACE(("leave buf_ed25519_verify: bad size"))

    goto out;

  }

  s = buf_getptr(buf, slen);

  if (dropbear_ed25519_verify(data_buf->data, data_buf->len,

            s, slen, key->pub) == 0) {

    /* signature is valid */

    TRACE(("leave buf_ed25519_verify: success!"))

    ret = DROPBEAR_SUCCESS;

  }

out:

  TRACE(("leave buf_ed25519_verify: ret %d", ret))

  return ret;

}

#endif /* DROPBEAR_SIGNKEY_VERIFY */

#endif /* DROPBEAR_ED25519 */