text: /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   *
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   *
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   *
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.] */
  
  #include <openssl/x509.h>
  
  #include <openssl/asn1.h>
  #include <openssl/digest.h>
  #include <openssl/err.h>
  #include <openssl/evp.h>
  #include <openssl/obj.h>
  
  #include "internal.h"
  
  
  int x509_digest_sign_algorithm(EVP_MD_CTX *ctx, X509_ALGOR *algor) {
    EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx->pctx);
    if (pkey == NULL) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_CONTEXT_NOT_INITIALISED);
      return 0;
    }
  
    if (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) {
      int pad_mode;
      if (!EVP_PKEY_CTX_get_rsa_padding(ctx->pctx, &pad_mode)) {
        return 0;
      }
      /* RSA-PSS has special signature algorithm logic. */
      if (pad_mode == RSA_PKCS1_PSS_PADDING) {
        return x509_rsa_ctx_to_pss(ctx, algor);
      }
    }
  
    if (EVP_PKEY_id(pkey) == EVP_PKEY_ED25519) {
      return X509_ALGOR_set0(algor, OBJ_nid2obj(NID_ED25519), V_ASN1_UNDEF, NULL);
    }
  
    /* Default behavior: look up the OID for the algorithm/hash pair and encode
     * that. */
    const EVP_MD *digest = EVP_MD_CTX_md(ctx);
    if (digest == NULL) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_CONTEXT_NOT_INITIALISED);
      return 0;
    }
  
    int sign_nid;
    if (!OBJ_find_sigid_by_algs(&sign_nid, EVP_MD_type(digest),
                                EVP_PKEY_id(pkey))) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_DIGEST_AND_KEY_TYPE_NOT_SUPPORTED);
      return 0;
    }
  
    /* RSA signature algorithms include an explicit NULL parameter. Others omit
     * it. */
    int paramtype =
        (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) ? V_ASN1_NULL : V_ASN1_UNDEF;
    X509_ALGOR_set0(algor, OBJ_nid2obj(sign_nid), paramtype, NULL);
    return 1;
  }
  
  int x509_digest_verify_init(EVP_MD_CTX *ctx, const X509_ALGOR *sigalg,
                              EVP_PKEY *pkey) {
    /* Convert the signature OID into digest and public key OIDs. */
    int sigalg_nid = OBJ_obj2nid(sigalg->algorithm);
    int digest_nid, pkey_nid;
    if (!OBJ_find_sigid_algs(sigalg_nid, &digest_nid, &pkey_nid)) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
      return 0;
    }
  
    /* Check the public key OID matches the public key type.
     * One special case is |EVP_PKEY_id(pkey)| may be |EVP_PKEY_RSA_PSS|.
     * This case happens when |OBJ_find_sigid_algs| returns |NID_rsaEncryption|
     * when |sigalg_nid| is |NID_rsassaPss|. */
    if (pkey_nid != EVP_PKEY_id(pkey) &&
        !(sigalg_nid == NID_rsassaPss && pkey_nid == NID_rsaEncryption &&
          EVP_PKEY_id(pkey) == EVP_PKEY_RSA_PSS)) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_PUBLIC_KEY_TYPE);
      return 0;
    }
  
    /* NID_undef signals that there are custom parameters to set. */
    if (digest_nid == NID_undef) {
      if (sigalg_nid == NID_rsassaPss) {
        return x509_rsa_pss_to_ctx(ctx, sigalg, pkey);
      }
      if (sigalg_nid == NID_ED25519) {
        if (sigalg->parameter != NULL) {
          OPENSSL_PUT_ERROR(X509, X509_R_INVALID_PARAMETER);
          return 0;
        }
        return EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey);
      }
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
      return 0;
    }
  
    /* The parameter should be an explicit NULL for RSA and omitted for ECDSA. For
     * compatibility, we allow either for both algorithms. See b/167375496.
     *
     * TODO(davidben): Chromium's verifier allows both forms for RSA, but enforces
     * ECDSA more strictly. Align with Chromium and add a flag for b/167375496. */
    if (sigalg->parameter != NULL && sigalg->parameter->type != V_ASN1_NULL) {
      OPENSSL_PUT_ERROR(X509, X509_R_INVALID_PARAMETER);
      return 0;
    }
  
    /* Otherwise, initialize with the digest from the OID. */
    const EVP_MD *digest = EVP_get_digestbynid(digest_nid);
    if (digest == NULL) {
      OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
      return 0;
    }
  
    return EVP_DigestVerifyInit(ctx, NULL, digest, NULL, pkey);
  }
  