text: /* Copyright (c) 2017, Google Inc.
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
   * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
  
  #include <openssl/evp.h>
  
  #include <openssl/curve25519.h>
  #include <openssl/err.h>
  
  #include "internal.h"
  
  
  // Ed25519 has no parameters to copy.
  static int pkey_ed25519_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src) { return 1; }
  
  static int pkey_ed25519_sign_message(EVP_PKEY_CTX *ctx, uint8_t *sig,
                                       size_t *siglen, const uint8_t *tbs,
                                       size_t tbslen) {
    ED25519_KEY *key = ctx->pkey->pkey.ptr;
    if (!key->has_private) {
      OPENSSL_PUT_ERROR(EVP, EVP_R_NOT_A_PRIVATE_KEY);
      return 0;
    }
  
    *siglen = 64;
    if (sig == NULL) {
      return 1;
    }
  
    return ED25519_sign(sig, tbs, tbslen, key->key.priv);
  }
  
  static int pkey_ed25519_verify_message(EVP_PKEY_CTX *ctx, const uint8_t *sig,
                                         size_t siglen, const uint8_t *tbs,
                                         size_t tbslen) {
    ED25519_KEY *key = ctx->pkey->pkey.ptr;
    if (siglen != 64 ||
        !ED25519_verify(tbs, tbslen, sig, key->key.pub.value)) {
      OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_SIGNATURE);
      return 0;
    }
  
    return 1;
  }
  
  const EVP_PKEY_METHOD ed25519_pkey_meth = {
      EVP_PKEY_ED25519,
      NULL /* init */,
      pkey_ed25519_copy,
      NULL /* cleanup */,
      NULL /* keygen */,
      NULL /* sign */,
      pkey_ed25519_sign_message,
      NULL /* verify */,
      pkey_ed25519_verify_message,
      NULL /* verify_recover */,
      NULL /* encrypt */,
      NULL /* decrypt */,
      NULL /* derive */,
      NULL /* paramgen */,
      NULL /* ctrl */,
  };
  