ssl/ssl_privkey.c - boringssl.git - Git at Google

 /* 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/ssl.h>

 #include <limits.h>

 #include <openssl/ec.h>
 #include <openssl/ec_key.h>
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/mem.h>
 #include <openssl/type_check.h>
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>

 #include "internal.h"


 int ssl_is_key_type_supported(int key_type) {
   return key_type == EVP_PKEY_RSA || key_type == EVP_PKEY_EC;
 }

 static int ssl_set_pkey(CERT *cert, EVP_PKEY *pkey) {
   if (!ssl_is_key_type_supported(pkey->type)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CERTIFICATE_TYPE);
     return 0;
   }

   if (cert->chain != NULL &&
       sk_CRYPTO_BUFFER_value(cert->chain, 0) != NULL &&
       /* Sanity-check that the private key and the certificate match, unless
        * the key is opaque (in case of, say, a smartcard). */
       !EVP_PKEY_is_opaque(pkey) &&
       !ssl_cert_check_private_key(cert, pkey)) {
     return 0;
   }

   EVP_PKEY_free(cert->privatekey);
   EVP_PKEY_up_ref(pkey);
   cert->privatekey = pkey;

   return 1;
 }

 int SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa) {
   EVP_PKEY *pkey;
   int ret;

   if (rsa == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
     return 0;
   }

   pkey = EVP_PKEY_new();
   if (pkey == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_EVP_LIB);
     return 0;
   }

   RSA_up_ref(rsa);
   EVP_PKEY_assign_RSA(pkey, rsa);

   ret = ssl_set_pkey(ssl->cert, pkey);
   EVP_PKEY_free(pkey);

   return ret;
 }

 int SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey) {
   if (pkey == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
     return 0;
   }

   return ssl_set_pkey(ssl->cert, pkey);
 }

 int SSL_use_PrivateKey_ASN1(int type, SSL *ssl, const uint8_t *der,
                             size_t der_len) {
   if (der_len > LONG_MAX) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
     return 0;
   }

   const uint8_t *p = der;
   EVP_PKEY *pkey = d2i_PrivateKey(type, NULL, &p, (long)der_len);
   if (pkey == NULL || p != der + der_len) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
     EVP_PKEY_free(pkey);
     return 0;
   }

   int ret = SSL_use_PrivateKey(ssl, pkey);
   EVP_PKEY_free(pkey);
   return ret;
 }

 int SSL_CTX_use_RSAPrivateKey(SSL_CTX *ctx, RSA *rsa) {
   int ret;
   EVP_PKEY *pkey;

   if (rsa == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
     return 0;
   }

   pkey = EVP_PKEY_new();
   if (pkey == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_EVP_LIB);
     return 0;
   }

   RSA_up_ref(rsa);
   EVP_PKEY_assign_RSA(pkey, rsa);

   ret = ssl_set_pkey(ctx->cert, pkey);
   EVP_PKEY_free(pkey);
   return ret;
 }

 int SSL_CTX_use_RSAPrivateKey_ASN1(SSL_CTX *ctx, const uint8_t *der,
                                    size_t der_len) {
   RSA *rsa = RSA_private_key_from_bytes(der, der_len);
   if (rsa == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
     return 0;
   }

   int ret = SSL_CTX_use_RSAPrivateKey(ctx, rsa);
   RSA_free(rsa);
   return ret;
 }

 int SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey) {
   if (pkey == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
     return 0;
   }

   return ssl_set_pkey(ctx->cert, pkey);
 }

 int SSL_CTX_use_PrivateKey_ASN1(int type, SSL_CTX *ctx, const uint8_t *der,
                                 size_t der_len) {
   if (der_len > LONG_MAX) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
     return 0;
   }

   const uint8_t *p = der;
   EVP_PKEY *pkey = d2i_PrivateKey(type, NULL, &p, (long)der_len);
   if (pkey == NULL || p != der + der_len) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
     EVP_PKEY_free(pkey);
     return 0;
   }

   int ret = SSL_CTX_use_PrivateKey(ctx, pkey);
   EVP_PKEY_free(pkey);
   return ret;
 }

 void SSL_set_private_key_method(SSL *ssl,
                                 const SSL_PRIVATE_KEY_METHOD *key_method) {
   ssl->cert->key_method = key_method;
 }

 void SSL_CTX_set_private_key_method(SSL_CTX *ctx,
                                     const SSL_PRIVATE_KEY_METHOD *key_method) {
   ctx->cert->key_method = key_method;
 }

 static int set_signing_algorithm_prefs(CERT *cert, const uint16_t *prefs,
                                        size_t num_prefs) {
   OPENSSL_free(cert->sigalgs);

   cert->num_sigalgs = 0;
   cert->sigalgs = BUF_memdup(prefs, num_prefs * sizeof(prefs[0]));
   if (cert->sigalgs == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return 0;
   }
   cert->num_sigalgs = num_prefs;

   return 1;
 }

 int SSL_CTX_set_signing_algorithm_prefs(SSL_CTX *ctx, const uint16_t *prefs,
                                         size_t num_prefs) {
   return set_signing_algorithm_prefs(ctx->cert, prefs, num_prefs);
 }


 int SSL_set_signing_algorithm_prefs(SSL *ssl, const uint16_t *prefs,
                                     size_t num_prefs) {
   return set_signing_algorithm_prefs(ssl->cert, prefs, num_prefs);
 }

 int SSL_set_private_key_digest_prefs(SSL *ssl, const int *digest_nids,
                                      size_t num_digests) {
   OPENSSL_free(ssl->cert->sigalgs);

   OPENSSL_COMPILE_ASSERT(sizeof(int) >= 2 * sizeof(uint16_t),
                          digest_list_conversion_cannot_overflow);

   ssl->cert->num_sigalgs = 0;
   ssl->cert->sigalgs = OPENSSL_malloc(sizeof(uint16_t) * 2 * num_digests);
   if (ssl->cert->sigalgs == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return 0;
   }

   /* Convert the digest list to a signature algorithms list.
    *
    * TODO(davidben): Replace this API with one that can express RSA-PSS, etc. */
   for (size_t i = 0; i < num_digests; i++) {
     switch (digest_nids[i]) {
       case NID_sha1:
         ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA1;
         ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] = SSL_SIGN_ECDSA_SHA1;
         ssl->cert->num_sigalgs += 2;
         break;
       case NID_sha256:
         ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA256;
         ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
             SSL_SIGN_ECDSA_SECP256R1_SHA256;
         ssl->cert->num_sigalgs += 2;
         break;
       case NID_sha384:
         ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA384;
         ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
             SSL_SIGN_ECDSA_SECP384R1_SHA384;
         ssl->cert->num_sigalgs += 2;
         break;
       case NID_sha512:
         ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA512;
         ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
             SSL_SIGN_ECDSA_SECP521R1_SHA512;
         ssl->cert->num_sigalgs += 2;
         break;
     }
   }

   return 1;
 }

 int ssl_has_private_key(const SSL *ssl) {
   return ssl->cert->privatekey != NULL || ssl->cert->key_method != NULL;
 }

 int ssl_is_ecdsa_key_type(int type) {
   switch (type) {
     /* TODO(davidben): Remove support for |EVP_PKEY_EC| key types. */
     case EVP_PKEY_EC:
     case NID_X9_62_prime256v1:
     case NID_secp384r1:
     case NID_secp521r1:
       return 1;
     default:
       return 0;
   }
 }

 int ssl_private_key_type(SSL *ssl) {
   if (ssl->cert->key_method != NULL) {
     return ssl->cert->key_method->type(ssl);
   }
   switch (EVP_PKEY_id(ssl->cert->privatekey)) {
     case EVP_PKEY_RSA:
       return NID_rsaEncryption;
     case EVP_PKEY_EC:
       return EC_GROUP_get_curve_name(
           EC_KEY_get0_group(EVP_PKEY_get0_EC_KEY(ssl->cert->privatekey)));
     default:
       return NID_undef;
   }
 }

 size_t ssl_private_key_max_signature_len(SSL *ssl) {
   if (ssl->cert->key_method != NULL) {
     return ssl->cert->key_method->max_signature_len(ssl);
   }
   return EVP_PKEY_size(ssl->cert->privatekey);
 }

 /* TODO(davidben): Forbid RSA-PKCS1 in TLS 1.3. For now we allow it because NSS
  * has yet to start doing RSA-PSS, so enforcing it would complicate interop
  * testing. */
 static int is_rsa_pkcs1(const EVP_MD **out_md, uint16_t sigalg) {
   switch (sigalg) {
     case SSL_SIGN_RSA_PKCS1_MD5_SHA1:
       *out_md = EVP_md5_sha1();
       return 1;
     case SSL_SIGN_RSA_PKCS1_SHA1:
       *out_md = EVP_sha1();
       return 1;
     case SSL_SIGN_RSA_PKCS1_SHA256:
       *out_md = EVP_sha256();
       return 1;
     case SSL_SIGN_RSA_PKCS1_SHA384:
       *out_md = EVP_sha384();
       return 1;
     case SSL_SIGN_RSA_PKCS1_SHA512:
       *out_md = EVP_sha512();
       return 1;
     default:
       return 0;
   }
 }

 static int ssl_sign_rsa_pkcs1(SSL *ssl, uint8_t *out, size_t *out_len,
                               size_t max_out, const EVP_MD *md,
                               const uint8_t *in, size_t in_len) {
   EVP_MD_CTX ctx;
   EVP_MD_CTX_init(&ctx);
   *out_len = max_out;
   int ret = EVP_DigestSignInit(&ctx, NULL, md, NULL, ssl->cert->privatekey) &&
             EVP_DigestSignUpdate(&ctx, in, in_len) &&
             EVP_DigestSignFinal(&ctx, out, out_len);
   EVP_MD_CTX_cleanup(&ctx);
   return ret;
 }

 static int ssl_verify_rsa_pkcs1(SSL *ssl, const uint8_t *signature,
                                 size_t signature_len, const EVP_MD *md,
                                 EVP_PKEY *pkey, const uint8_t *in,
                                 size_t in_len) {
   if (pkey->type != EVP_PKEY_RSA) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   EVP_MD_CTX md_ctx;
   EVP_MD_CTX_init(&md_ctx);
   int ret = EVP_DigestVerifyInit(&md_ctx, NULL, md, NULL, pkey) &&
             EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
             EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
   EVP_MD_CTX_cleanup(&md_ctx);
   return ret;
 }

 static int is_ecdsa(int *out_curve, const EVP_MD **out_md, uint16_t sigalg) {
   switch (sigalg) {
     case SSL_SIGN_ECDSA_SHA1:
       *out_curve = NID_undef;
       *out_md = EVP_sha1();
       return 1;
     case SSL_SIGN_ECDSA_SECP256R1_SHA256:
       *out_curve = NID_X9_62_prime256v1;
       *out_md = EVP_sha256();
       return 1;
     case SSL_SIGN_ECDSA_SECP384R1_SHA384:
       *out_curve = NID_secp384r1;
       *out_md = EVP_sha384();
       return 1;
     case SSL_SIGN_ECDSA_SECP521R1_SHA512:
       *out_curve = NID_secp521r1;
       *out_md = EVP_sha512();
       return 1;
     default:
       return 0;
   }
 }

 static int ssl_sign_ecdsa(SSL *ssl, uint8_t *out, size_t *out_len,
                           size_t max_out, int curve, const EVP_MD *md,
                           const uint8_t *in, size_t in_len) {
   EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(ssl->cert->privatekey);
   if (ec_key == NULL) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   /* In TLS 1.3, the curve is also specified by the signature algorithm. */
   if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION &&
       (curve == NID_undef ||
        EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) != curve)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   EVP_MD_CTX ctx;
   EVP_MD_CTX_init(&ctx);
   *out_len = max_out;
   int ret = EVP_DigestSignInit(&ctx, NULL, md, NULL, ssl->cert->privatekey) &&
             EVP_DigestSignUpdate(&ctx, in, in_len) &&
             EVP_DigestSignFinal(&ctx, out, out_len);
   EVP_MD_CTX_cleanup(&ctx);
   return ret;
 }

 static int ssl_verify_ecdsa(SSL *ssl, const uint8_t *signature,
                             size_t signature_len, int curve, const EVP_MD *md,
                             EVP_PKEY *pkey, const uint8_t *in, size_t in_len) {
   EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(pkey);
   if (ec_key == NULL) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   /* In TLS 1.3, the curve is also specified by the signature algorithm. */
   if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION &&
       (curve == NID_undef ||
        EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) != curve)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   EVP_MD_CTX md_ctx;
   EVP_MD_CTX_init(&md_ctx);
   int ret = EVP_DigestVerifyInit(&md_ctx, NULL, md, NULL, pkey) &&
             EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
             EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
   EVP_MD_CTX_cleanup(&md_ctx);
   return ret;
 }

 static int is_rsa_pss(const EVP_MD **out_md, uint16_t sigalg) {
   switch (sigalg) {
     case SSL_SIGN_RSA_PSS_SHA256:
       *out_md = EVP_sha256();
       return 1;
     case SSL_SIGN_RSA_PSS_SHA384:
       *out_md = EVP_sha384();
       return 1;
     case SSL_SIGN_RSA_PSS_SHA512:
       *out_md = EVP_sha512();
       return 1;
     default:
       return 0;
   }
 }

 static int ssl_sign_rsa_pss(SSL *ssl, uint8_t *out, size_t *out_len,
                               size_t max_out, const EVP_MD *md,
                               const uint8_t *in, size_t in_len) {
   EVP_MD_CTX ctx;
   EVP_MD_CTX_init(&ctx);
   *out_len = max_out;
   EVP_PKEY_CTX *pctx;
   int ret =
       EVP_DigestSignInit(&ctx, &pctx, md, NULL, ssl->cert->privatekey) &&
       EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) &&
       EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1 /* salt len = hash len */) &&
       EVP_DigestSignUpdate(&ctx, in, in_len) &&
       EVP_DigestSignFinal(&ctx, out, out_len);
   EVP_MD_CTX_cleanup(&ctx);
   return ret;
 }

 static int ssl_verify_rsa_pss(SSL *ssl, const uint8_t *signature,
                                 size_t signature_len, const EVP_MD *md,
                                 EVP_PKEY *pkey, const uint8_t *in,
                                 size_t in_len) {
   if (pkey->type != EVP_PKEY_RSA) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
     return 0;
   }

   EVP_MD_CTX md_ctx;
   EVP_MD_CTX_init(&md_ctx);
   EVP_PKEY_CTX *pctx;
   int ret =
       EVP_DigestVerifyInit(&md_ctx, &pctx, md, NULL, pkey) &&
       EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) &&
       EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1 /* salt len = hash len */) &&
       EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
       EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
   EVP_MD_CTX_cleanup(&md_ctx);
   return ret;
 }

 enum ssl_private_key_result_t ssl_private_key_sign(
     SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
     uint16_t signature_algorithm, const uint8_t *in, size_t in_len) {
   if (ssl->cert->key_method != NULL) {
     if (ssl->cert->key_method->sign != NULL) {
       return ssl->cert->key_method->sign(ssl, out, out_len, max_out,
                                          signature_algorithm, in, in_len);
     }

     /* TODO(davidben): Remove support for |sign_digest|-only
      * |SSL_PRIVATE_KEY_METHOD|s. */
     const EVP_MD *md;
     int curve;
     if (!is_rsa_pkcs1(&md, signature_algorithm) &&
         !is_ecdsa(&curve, &md, signature_algorithm)) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_PROTOCOL_FOR_CUSTOM_KEY);
       return ssl_private_key_failure;
     }

     uint8_t hash[EVP_MAX_MD_SIZE];
     unsigned hash_len;
     if (!EVP_Digest(in, in_len, hash, &hash_len, md, NULL)) {
       return ssl_private_key_failure;
     }

     return ssl->cert->key_method->sign_digest(ssl, out, out_len, max_out, md,
                                               hash, hash_len);
   }

   const EVP_MD *md;
   if (is_rsa_pkcs1(&md, signature_algorithm) &&
       ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
     return ssl_sign_rsa_pkcs1(ssl, out, out_len, max_out, md, in, in_len)
                ? ssl_private_key_success
                : ssl_private_key_failure;
   }

   int curve;
   if (is_ecdsa(&curve, &md, signature_algorithm)) {
     return ssl_sign_ecdsa(ssl, out, out_len, max_out, curve, md, in, in_len)
                ? ssl_private_key_success
                : ssl_private_key_failure;
   }

   if (is_rsa_pss(&md, signature_algorithm)) {
     return ssl_sign_rsa_pss(ssl, out, out_len, max_out, md, in, in_len)
                ? ssl_private_key_success
                : ssl_private_key_failure;
   }

   OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
   return ssl_private_key_failure;
 }

 int ssl_public_key_verify(SSL *ssl, const uint8_t *signature,
                           size_t signature_len, uint16_t signature_algorithm,
                           EVP_PKEY *pkey, const uint8_t *in, size_t in_len) {
   const EVP_MD *md;
   if (is_rsa_pkcs1(&md, signature_algorithm) &&
       ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
     return ssl_verify_rsa_pkcs1(ssl, signature, signature_len, md, pkey, in,
                                 in_len);
   }

   int curve;
   if (is_ecdsa(&curve, &md, signature_algorithm)) {
     return ssl_verify_ecdsa(ssl, signature, signature_len, curve, md, pkey, in,
                             in_len);
   }

   if (is_rsa_pss(&md, signature_algorithm)) {
     return ssl_verify_rsa_pss(ssl, signature, signature_len, md, pkey, in,
                               in_len);
   }

   OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
   return 0;
 }

 enum ssl_private_key_result_t ssl_private_key_decrypt(
     SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
     const uint8_t *in, size_t in_len) {
   if (ssl->cert->key_method != NULL) {
     return ssl->cert->key_method->decrypt(ssl, out, out_len, max_out, in,
                                           in_len);
   }

   RSA *rsa = EVP_PKEY_get0_RSA(ssl->cert->privatekey);
   if (rsa == NULL) {
     /* Decrypt operations are only supported for RSA keys. */
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     return ssl_private_key_failure;
   }

   /* Decrypt with no padding. PKCS#1 padding will be removed as part
    * of the timing-sensitive code by the caller. */
   if (!RSA_decrypt(rsa, out_len, out, max_out, in, in_len, RSA_NO_PADDING)) {
     return ssl_private_key_failure;
   }
   return ssl_private_key_success;
 }

 enum ssl_private_key_result_t ssl_private_key_complete(SSL *ssl, uint8_t *out,
                                                        size_t *out_len,
                                                        size_t max_out) {
   /* Only custom keys may be asynchronous. */
   return ssl->cert->key_method->complete(ssl, out, out_len, max_out);
 }

 int ssl_private_key_supports_signature_algorithm(SSL *ssl,
                                                  uint16_t signature_algorithm) {
   const EVP_MD *md;
   if (is_rsa_pkcs1(&md, signature_algorithm) &&
       ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
     return ssl_private_key_type(ssl) == NID_rsaEncryption;
   }

   int curve;
   if (is_ecdsa(&curve, &md, signature_algorithm)) {
     int type = ssl_private_key_type(ssl);
     if (!ssl_is_ecdsa_key_type(type)) {
       return 0;
     }

     /* Prior to TLS 1.3, ECDSA curves did not match the signature algorithm. */
     if (ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
       return 1;
     }

     return curve != NID_undef && type == curve;
   }

   if (is_rsa_pss(&md, signature_algorithm)) {
     if (ssl_private_key_type(ssl) != NID_rsaEncryption) {
       return 0;
     }

     /* Ensure the RSA key is large enough for the hash. RSASSA-PSS requires that
      * emLen be at least hLen + sLen + 2. Both hLen and sLen are the size of the
      * hash in TLS. Reasonable RSA key sizes are large enough for the largest
      * defined RSASSA-PSS algorithm, but 1024-bit RSA is slightly too large for
      * SHA-512. 1024-bit RSA is sometimes used for test credentials, so check
      * the size to fall back to another algorithm. */
     if (ssl_private_key_max_signature_len(ssl) < 2 * EVP_MD_size(md) + 2) {
       return 0;
     }

     /* RSA-PSS is only supported by message-based private keys. */
     if (ssl->cert->key_method != NULL && ssl->cert->key_method->sign == NULL) {
       return 0;
     }

     return 1;
   }

   return 0;
 }
	/* 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/ssl.h>

	#include <limits.h>

	#include <openssl/ec.h>
	#include <openssl/ec_key.h>
	#include <openssl/err.h>
	#include <openssl/evp.h>
	#include <openssl/mem.h>
	#include <openssl/type_check.h>
	#include <openssl/x509.h>
	#include <openssl/x509v3.h>

	#include "internal.h"


	int ssl_is_key_type_supported(int key_type) {
	return key_type == EVP_PKEY_RSA \|\| key_type == EVP_PKEY_EC;
	}

	static int ssl_set_pkey(CERT cert, EVP_PKEY pkey) {
	if (!ssl_is_key_type_supported(pkey->type)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CERTIFICATE_TYPE);
	return 0;
	}

	if (cert->chain != NULL &&
	sk_CRYPTO_BUFFER_value(cert->chain, 0) != NULL &&
	/* Sanity-check that the private key and the certificate match, unless
	* the key is opaque (in case of, say, a smartcard). */
	!EVP_PKEY_is_opaque(pkey) &&
	!ssl_cert_check_private_key(cert, pkey)) {
	return 0;
	}

	EVP_PKEY_free(cert->privatekey);
	EVP_PKEY_up_ref(pkey);
	cert->privatekey = pkey;

	return 1;
	}

	int SSL_use_RSAPrivateKey(SSL ssl, RSA rsa) {
	EVP_PKEY *pkey;
	int ret;

	if (rsa == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	pkey = EVP_PKEY_new();
	if (pkey == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_EVP_LIB);
	return 0;
	}

	RSA_up_ref(rsa);
	EVP_PKEY_assign_RSA(pkey, rsa);

	ret = ssl_set_pkey(ssl->cert, pkey);
	EVP_PKEY_free(pkey);

	return ret;
	}

	int SSL_use_PrivateKey(SSL ssl, EVP_PKEY pkey) {
	if (pkey == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	return ssl_set_pkey(ssl->cert, pkey);
	}

	int SSL_use_PrivateKey_ASN1(int type, SSL ssl, const uint8_t der,
	size_t der_len) {
	if (der_len > LONG_MAX) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
	return 0;
	}

	const uint8_t *p = der;
	EVP_PKEY *pkey = d2i_PrivateKey(type, NULL, &p, (long)der_len);
	if (pkey == NULL \|\| p != der + der_len) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
	EVP_PKEY_free(pkey);
	return 0;
	}

	int ret = SSL_use_PrivateKey(ssl, pkey);
	EVP_PKEY_free(pkey);
	return ret;
	}

	int SSL_CTX_use_RSAPrivateKey(SSL_CTX ctx, RSA rsa) {
	int ret;
	EVP_PKEY *pkey;

	if (rsa == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	pkey = EVP_PKEY_new();
	if (pkey == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_EVP_LIB);
	return 0;
	}

	RSA_up_ref(rsa);
	EVP_PKEY_assign_RSA(pkey, rsa);

	ret = ssl_set_pkey(ctx->cert, pkey);
	EVP_PKEY_free(pkey);
	return ret;
	}

	int SSL_CTX_use_RSAPrivateKey_ASN1(SSL_CTX ctx, const uint8_t der,
	size_t der_len) {
	RSA *rsa = RSA_private_key_from_bytes(der, der_len);
	if (rsa == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
	return 0;
	}

	int ret = SSL_CTX_use_RSAPrivateKey(ctx, rsa);
	RSA_free(rsa);
	return ret;
	}

	int SSL_CTX_use_PrivateKey(SSL_CTX ctx, EVP_PKEY pkey) {
	if (pkey == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	return ssl_set_pkey(ctx->cert, pkey);
	}

	int SSL_CTX_use_PrivateKey_ASN1(int type, SSL_CTX ctx, const uint8_t der,
	size_t der_len) {
	if (der_len > LONG_MAX) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
	return 0;
	}

	const uint8_t *p = der;
	EVP_PKEY *pkey = d2i_PrivateKey(type, NULL, &p, (long)der_len);
	if (pkey == NULL \|\| p != der + der_len) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_ASN1_LIB);
	EVP_PKEY_free(pkey);
	return 0;
	}

	int ret = SSL_CTX_use_PrivateKey(ctx, pkey);
	EVP_PKEY_free(pkey);
	return ret;
	}

	void SSL_set_private_key_method(SSL *ssl,
	const SSL_PRIVATE_KEY_METHOD *key_method) {
	ssl->cert->key_method = key_method;
	}

	void SSL_CTX_set_private_key_method(SSL_CTX *ctx,
	const SSL_PRIVATE_KEY_METHOD *key_method) {
	ctx->cert->key_method = key_method;
	}

	static int set_signing_algorithm_prefs(CERT cert, const uint16_t prefs,
	size_t num_prefs) {
	OPENSSL_free(cert->sigalgs);

	cert->num_sigalgs = 0;
	cert->sigalgs = BUF_memdup(prefs, num_prefs * sizeof(prefs[0]));
	if (cert->sigalgs == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	cert->num_sigalgs = num_prefs;

	return 1;
	}

	int SSL_CTX_set_signing_algorithm_prefs(SSL_CTX ctx, const uint16_t prefs,
	size_t num_prefs) {
	return set_signing_algorithm_prefs(ctx->cert, prefs, num_prefs);
	}


	int SSL_set_signing_algorithm_prefs(SSL ssl, const uint16_t prefs,
	size_t num_prefs) {
	return set_signing_algorithm_prefs(ssl->cert, prefs, num_prefs);
	}

	int SSL_set_private_key_digest_prefs(SSL ssl, const int digest_nids,
	size_t num_digests) {
	OPENSSL_free(ssl->cert->sigalgs);

	OPENSSL_COMPILE_ASSERT(sizeof(int) >= 2 * sizeof(uint16_t),
	digest_list_conversion_cannot_overflow);

	ssl->cert->num_sigalgs = 0;
	ssl->cert->sigalgs = OPENSSL_malloc(sizeof(uint16_t) * 2 * num_digests);
	if (ssl->cert->sigalgs == NULL) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	/* Convert the digest list to a signature algorithms list.
	*
	* TODO(davidben): Replace this API with one that can express RSA-PSS, etc. */
	for (size_t i = 0; i < num_digests; i++) {
	switch (digest_nids[i]) {
	case NID_sha1:
	ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA1;
	ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] = SSL_SIGN_ECDSA_SHA1;
	ssl->cert->num_sigalgs += 2;
	break;
	case NID_sha256:
	ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA256;
	ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
	SSL_SIGN_ECDSA_SECP256R1_SHA256;
	ssl->cert->num_sigalgs += 2;
	break;
	case NID_sha384:
	ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA384;
	ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
	SSL_SIGN_ECDSA_SECP384R1_SHA384;
	ssl->cert->num_sigalgs += 2;
	break;
	case NID_sha512:
	ssl->cert->sigalgs[ssl->cert->num_sigalgs] = SSL_SIGN_RSA_PKCS1_SHA512;
	ssl->cert->sigalgs[ssl->cert->num_sigalgs + 1] =
	SSL_SIGN_ECDSA_SECP521R1_SHA512;
	ssl->cert->num_sigalgs += 2;
	break;
	}
	}

	return 1;
	}

	int ssl_has_private_key(const SSL *ssl) {
	return ssl->cert->privatekey != NULL \|\| ssl->cert->key_method != NULL;
	}

	int ssl_is_ecdsa_key_type(int type) {
	switch (type) {
	/* TODO(davidben): Remove support for \|EVP_PKEY_EC\| key types. */
	case EVP_PKEY_EC:
	case NID_X9_62_prime256v1:
	case NID_secp384r1:
	case NID_secp521r1:
	return 1;
	default:
	return 0;
	}
	}

	int ssl_private_key_type(SSL *ssl) {
	if (ssl->cert->key_method != NULL) {
	return ssl->cert->key_method->type(ssl);
	}
	switch (EVP_PKEY_id(ssl->cert->privatekey)) {
	case EVP_PKEY_RSA:
	return NID_rsaEncryption;
	case EVP_PKEY_EC:
	return EC_GROUP_get_curve_name(
	EC_KEY_get0_group(EVP_PKEY_get0_EC_KEY(ssl->cert->privatekey)));
	default:
	return NID_undef;
	}
	}

	size_t ssl_private_key_max_signature_len(SSL *ssl) {
	if (ssl->cert->key_method != NULL) {
	return ssl->cert->key_method->max_signature_len(ssl);
	}
	return EVP_PKEY_size(ssl->cert->privatekey);
	}

	/* TODO(davidben): Forbid RSA-PKCS1 in TLS 1.3. For now we allow it because NSS
	* has yet to start doing RSA-PSS, so enforcing it would complicate interop
	* testing. */
	static int is_rsa_pkcs1(const EVP_MD **out_md, uint16_t sigalg) {
	switch (sigalg) {
	case SSL_SIGN_RSA_PKCS1_MD5_SHA1:
	*out_md = EVP_md5_sha1();
	return 1;
	case SSL_SIGN_RSA_PKCS1_SHA1:
	*out_md = EVP_sha1();
	return 1;
	case SSL_SIGN_RSA_PKCS1_SHA256:
	*out_md = EVP_sha256();
	return 1;
	case SSL_SIGN_RSA_PKCS1_SHA384:
	*out_md = EVP_sha384();
	return 1;
	case SSL_SIGN_RSA_PKCS1_SHA512:
	*out_md = EVP_sha512();
	return 1;
	default:
	return 0;
	}
	}

	static int ssl_sign_rsa_pkcs1(SSL ssl, uint8_t out, size_t *out_len,
	size_t max_out, const EVP_MD *md,
	const uint8_t *in, size_t in_len) {
	EVP_MD_CTX ctx;
	EVP_MD_CTX_init(&ctx);
	*out_len = max_out;
	int ret = EVP_DigestSignInit(&ctx, NULL, md, NULL, ssl->cert->privatekey) &&
	EVP_DigestSignUpdate(&ctx, in, in_len) &&
	EVP_DigestSignFinal(&ctx, out, out_len);
	EVP_MD_CTX_cleanup(&ctx);
	return ret;
	}

	static int ssl_verify_rsa_pkcs1(SSL ssl, const uint8_t signature,
	size_t signature_len, const EVP_MD *md,
	EVP_PKEY pkey, const uint8_t in,
	size_t in_len) {
	if (pkey->type != EVP_PKEY_RSA) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	EVP_MD_CTX md_ctx;
	EVP_MD_CTX_init(&md_ctx);
	int ret = EVP_DigestVerifyInit(&md_ctx, NULL, md, NULL, pkey) &&
	EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
	EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
	EVP_MD_CTX_cleanup(&md_ctx);
	return ret;
	}

	static int is_ecdsa(int out_curve, const EVP_MD *out_md, uint16_t sigalg) {
	switch (sigalg) {
	case SSL_SIGN_ECDSA_SHA1:
	*out_curve = NID_undef;
	*out_md = EVP_sha1();
	return 1;
	case SSL_SIGN_ECDSA_SECP256R1_SHA256:
	*out_curve = NID_X9_62_prime256v1;
	*out_md = EVP_sha256();
	return 1;
	case SSL_SIGN_ECDSA_SECP384R1_SHA384:
	*out_curve = NID_secp384r1;
	*out_md = EVP_sha384();
	return 1;
	case SSL_SIGN_ECDSA_SECP521R1_SHA512:
	*out_curve = NID_secp521r1;
	*out_md = EVP_sha512();
	return 1;
	default:
	return 0;
	}
	}

	static int ssl_sign_ecdsa(SSL ssl, uint8_t out, size_t *out_len,
	size_t max_out, int curve, const EVP_MD *md,
	const uint8_t *in, size_t in_len) {
	EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(ssl->cert->privatekey);
	if (ec_key == NULL) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	/* In TLS 1.3, the curve is also specified by the signature algorithm. */
	if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION &&
	(curve == NID_undef \|\|
	EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) != curve)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	EVP_MD_CTX ctx;
	EVP_MD_CTX_init(&ctx);
	*out_len = max_out;
	int ret = EVP_DigestSignInit(&ctx, NULL, md, NULL, ssl->cert->privatekey) &&
	EVP_DigestSignUpdate(&ctx, in, in_len) &&
	EVP_DigestSignFinal(&ctx, out, out_len);
	EVP_MD_CTX_cleanup(&ctx);
	return ret;
	}

	static int ssl_verify_ecdsa(SSL ssl, const uint8_t signature,
	size_t signature_len, int curve, const EVP_MD *md,
	EVP_PKEY pkey, const uint8_t in, size_t in_len) {
	EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(pkey);
	if (ec_key == NULL) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	/* In TLS 1.3, the curve is also specified by the signature algorithm. */
	if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION &&
	(curve == NID_undef \|\|
	EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) != curve)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	EVP_MD_CTX md_ctx;
	EVP_MD_CTX_init(&md_ctx);
	int ret = EVP_DigestVerifyInit(&md_ctx, NULL, md, NULL, pkey) &&
	EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
	EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
	EVP_MD_CTX_cleanup(&md_ctx);
	return ret;
	}

	static int is_rsa_pss(const EVP_MD **out_md, uint16_t sigalg) {
	switch (sigalg) {
	case SSL_SIGN_RSA_PSS_SHA256:
	*out_md = EVP_sha256();
	return 1;
	case SSL_SIGN_RSA_PSS_SHA384:
	*out_md = EVP_sha384();
	return 1;
	case SSL_SIGN_RSA_PSS_SHA512:
	*out_md = EVP_sha512();
	return 1;
	default:
	return 0;
	}
	}

	static int ssl_sign_rsa_pss(SSL ssl, uint8_t out, size_t *out_len,
	size_t max_out, const EVP_MD *md,
	const uint8_t *in, size_t in_len) {
	EVP_MD_CTX ctx;
	EVP_MD_CTX_init(&ctx);
	*out_len = max_out;
	EVP_PKEY_CTX *pctx;
	int ret =
	EVP_DigestSignInit(&ctx, &pctx, md, NULL, ssl->cert->privatekey) &&
	EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) &&
	EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1 /* salt len = hash len */) &&
	EVP_DigestSignUpdate(&ctx, in, in_len) &&
	EVP_DigestSignFinal(&ctx, out, out_len);
	EVP_MD_CTX_cleanup(&ctx);
	return ret;
	}

	static int ssl_verify_rsa_pss(SSL ssl, const uint8_t signature,
	size_t signature_len, const EVP_MD *md,
	EVP_PKEY pkey, const uint8_t in,
	size_t in_len) {
	if (pkey->type != EVP_PKEY_RSA) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	EVP_MD_CTX md_ctx;
	EVP_MD_CTX_init(&md_ctx);
	EVP_PKEY_CTX *pctx;
	int ret =
	EVP_DigestVerifyInit(&md_ctx, &pctx, md, NULL, pkey) &&
	EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) &&
	EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1 /* salt len = hash len */) &&
	EVP_DigestVerifyUpdate(&md_ctx, in, in_len) &&
	EVP_DigestVerifyFinal(&md_ctx, signature, signature_len);
	EVP_MD_CTX_cleanup(&md_ctx);
	return ret;
	}

	enum ssl_private_key_result_t ssl_private_key_sign(
	SSL ssl, uint8_t out, size_t *out_len, size_t max_out,
	uint16_t signature_algorithm, const uint8_t *in, size_t in_len) {
	if (ssl->cert->key_method != NULL) {
	if (ssl->cert->key_method->sign != NULL) {
	return ssl->cert->key_method->sign(ssl, out, out_len, max_out,
	signature_algorithm, in, in_len);
	}

	/* TODO(davidben): Remove support for \|sign_digest\|-only
	* \|SSL_PRIVATE_KEY_METHOD\|s. */
	const EVP_MD *md;
	int curve;
	if (!is_rsa_pkcs1(&md, signature_algorithm) &&
	!is_ecdsa(&curve, &md, signature_algorithm)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_PROTOCOL_FOR_CUSTOM_KEY);
	return ssl_private_key_failure;
	}

	uint8_t hash[EVP_MAX_MD_SIZE];
	unsigned hash_len;
	if (!EVP_Digest(in, in_len, hash, &hash_len, md, NULL)) {
	return ssl_private_key_failure;
	}

	return ssl->cert->key_method->sign_digest(ssl, out, out_len, max_out, md,
	hash, hash_len);
	}

	const EVP_MD *md;
	if (is_rsa_pkcs1(&md, signature_algorithm) &&
	ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
	return ssl_sign_rsa_pkcs1(ssl, out, out_len, max_out, md, in, in_len)
	? ssl_private_key_success
	: ssl_private_key_failure;
	}

	int curve;
	if (is_ecdsa(&curve, &md, signature_algorithm)) {
	return ssl_sign_ecdsa(ssl, out, out_len, max_out, curve, md, in, in_len)
	? ssl_private_key_success
	: ssl_private_key_failure;
	}

	if (is_rsa_pss(&md, signature_algorithm)) {
	return ssl_sign_rsa_pss(ssl, out, out_len, max_out, md, in, in_len)
	? ssl_private_key_success
	: ssl_private_key_failure;
	}

	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return ssl_private_key_failure;
	}

	int ssl_public_key_verify(SSL ssl, const uint8_t signature,
	size_t signature_len, uint16_t signature_algorithm,
	EVP_PKEY pkey, const uint8_t in, size_t in_len) {
	const EVP_MD *md;
	if (is_rsa_pkcs1(&md, signature_algorithm) &&
	ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
	return ssl_verify_rsa_pkcs1(ssl, signature, signature_len, md, pkey, in,
	in_len);
	}

	int curve;
	if (is_ecdsa(&curve, &md, signature_algorithm)) {
	return ssl_verify_ecdsa(ssl, signature, signature_len, curve, md, pkey, in,
	in_len);
	}

	if (is_rsa_pss(&md, signature_algorithm)) {
	return ssl_verify_rsa_pss(ssl, signature, signature_len, md, pkey, in,
	in_len);
	}

	OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
	return 0;
	}

	enum ssl_private_key_result_t ssl_private_key_decrypt(
	SSL ssl, uint8_t out, size_t *out_len, size_t max_out,
	const uint8_t *in, size_t in_len) {
	if (ssl->cert->key_method != NULL) {
	return ssl->cert->key_method->decrypt(ssl, out, out_len, max_out, in,
	in_len);
	}

	RSA *rsa = EVP_PKEY_get0_RSA(ssl->cert->privatekey);
	if (rsa == NULL) {
	/* Decrypt operations are only supported for RSA keys. */
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	return ssl_private_key_failure;
	}

	/* Decrypt with no padding. PKCS#1 padding will be removed as part
	* of the timing-sensitive code by the caller. */
	if (!RSA_decrypt(rsa, out_len, out, max_out, in, in_len, RSA_NO_PADDING)) {
	return ssl_private_key_failure;
	}
	return ssl_private_key_success;
	}

	enum ssl_private_key_result_t ssl_private_key_complete(SSL ssl, uint8_t out,
	size_t *out_len,
	size_t max_out) {
	/* Only custom keys may be asynchronous. */
	return ssl->cert->key_method->complete(ssl, out, out_len, max_out);
	}

	int ssl_private_key_supports_signature_algorithm(SSL *ssl,
	uint16_t signature_algorithm) {
	const EVP_MD *md;
	if (is_rsa_pkcs1(&md, signature_algorithm) &&
	ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
	return ssl_private_key_type(ssl) == NID_rsaEncryption;
	}

	int curve;
	if (is_ecdsa(&curve, &md, signature_algorithm)) {
	int type = ssl_private_key_type(ssl);
	if (!ssl_is_ecdsa_key_type(type)) {
	return 0;
	}

	/* Prior to TLS 1.3, ECDSA curves did not match the signature algorithm. */
	if (ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
	return 1;
	}

	return curve != NID_undef && type == curve;
	}

	if (is_rsa_pss(&md, signature_algorithm)) {
	if (ssl_private_key_type(ssl) != NID_rsaEncryption) {
	return 0;
	}

	/* Ensure the RSA key is large enough for the hash. RSASSA-PSS requires that
	* emLen be at least hLen + sLen + 2. Both hLen and sLen are the size of the
	* hash in TLS. Reasonable RSA key sizes are large enough for the largest
	* defined RSASSA-PSS algorithm, but 1024-bit RSA is slightly too large for
	* SHA-512. 1024-bit RSA is sometimes used for test credentials, so check
	* the size to fall back to another algorithm. */
	if (ssl_private_key_max_signature_len(ssl) < 2 * EVP_MD_size(md) + 2) {
	return 0;
	}

	/* RSA-PSS is only supported by message-based private keys. */
	if (ssl->cert->key_method != NULL && ssl->cert->key_method->sign == NULL) {
	return 0;
	}

	return 1;
	}

	return 0;
	}