text: /* crypto/rsa/rsa_sign.c */
  /* 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 <stdio.h>
  #include "cryptlib.h"
  #include <openssl/bn.h>
  #include <openssl/rsa.h>
  #include <openssl/objects.h>
  #include <openssl/x509.h>
  #include "rsa_locl.h"
  
  /* Size of an SSL signature: MD5+SHA1 */
  #define SSL_SIG_LENGTH  36
  
  int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
               unsigned char *sigret, unsigned int *siglen, RSA *rsa)
  {
      X509_SIG sig;
      ASN1_TYPE parameter;
      int i, j, ret = 1;
      unsigned char *p, *tmps = NULL;
      const unsigned char *s = NULL;
      X509_ALGOR algor;
      ASN1_OCTET_STRING digest;
  #ifdef OPENSSL_FIPS
      if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)
          && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {
          RSAerr(RSA_F_RSA_SIGN, RSA_R_NON_FIPS_RSA_METHOD);
          return 0;
      }
  #endif
      if ((rsa->meth->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_sign) {
          return rsa->meth->rsa_sign(type, m, m_len, sigret, siglen, rsa);
      }
      /* Special case: SSL signature, just check the length */
      if (type == NID_md5_sha1) {
          if (m_len != SSL_SIG_LENGTH) {
              RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
              return (0);
          }
          i = SSL_SIG_LENGTH;
          s = m;
      } else {
          sig.algor = &algor;
          sig.algor->algorithm = OBJ_nid2obj(type);
          if (sig.algor->algorithm == NULL) {
              RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
              return (0);
          }
          if (sig.algor->algorithm->length == 0) {
              RSAerr(RSA_F_RSA_SIGN,
                     RSA_R_THE_ASN1_OBJECT_IDENTIFIER_IS_NOT_KNOWN_FOR_THIS_MD);
              return (0);
          }
          parameter.type = V_ASN1_NULL;
          parameter.value.ptr = NULL;
          sig.algor->parameter = &parameter;
  
          sig.digest = &digest;
          sig.digest->data = (unsigned char *)m; /* TMP UGLY CAST */
          sig.digest->length = m_len;
  
          i = i2d_X509_SIG(&sig, NULL);
      }
      j = RSA_size(rsa);
      if (i > (j - RSA_PKCS1_PADDING_SIZE)) {
          RSAerr(RSA_F_RSA_SIGN, RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY);
          return (0);
      }
      if (type != NID_md5_sha1) {
          tmps = (unsigned char *)OPENSSL_malloc((unsigned int)j + 1);
          if (tmps == NULL) {
              RSAerr(RSA_F_RSA_SIGN, ERR_R_MALLOC_FAILURE);
              return (0);
          }
          p = tmps;
          i2d_X509_SIG(&sig, &p);
          s = tmps;
      }
      i = RSA_private_encrypt(i, s, sigret, rsa, RSA_PKCS1_PADDING);
      if (i <= 0)
          ret = 0;
      else
          *siglen = i;
  
      if (type != NID_md5_sha1) {
          OPENSSL_cleanse(tmps, (unsigned int)j + 1);
          OPENSSL_free(tmps);
      }
      return (ret);
  }
  
  /*
   * Check DigestInfo structure does not contain extraneous data by reencoding
   * using DER and checking encoding against original.
   */
  static int rsa_check_digestinfo(X509_SIG *sig, const unsigned char *dinfo,
                                  int dinfolen)
  {
      unsigned char *der = NULL;
      int derlen;
      int ret = 0;
      derlen = i2d_X509_SIG(sig, &der);
      if (derlen <= 0)
          return 0;
      if (derlen == dinfolen && !memcmp(dinfo, der, derlen))
          ret = 1;
      OPENSSL_cleanse(der, derlen);
      OPENSSL_free(der);
      return ret;
  }
  
  int int_rsa_verify(int dtype, const unsigned char *m,
                     unsigned int m_len,
                     unsigned char *rm, size_t *prm_len,
                     const unsigned char *sigbuf, size_t siglen, RSA *rsa)
  {
      int i, ret = 0, sigtype;
      unsigned char *s;
      X509_SIG *sig = NULL;
  
  #ifdef OPENSSL_FIPS
      if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)
          && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {
          RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_NON_FIPS_RSA_METHOD);
          return 0;
      }
  #endif
  
      if (siglen != (unsigned int)RSA_size(rsa)) {
          RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_WRONG_SIGNATURE_LENGTH);
          return (0);
      }
  
      if ((dtype == NID_md5_sha1) && rm) {
          i = RSA_public_decrypt((int)siglen,
                                 sigbuf, rm, rsa, RSA_PKCS1_PADDING);
          if (i <= 0)
              return 0;
          *prm_len = i;
          return 1;
      }
  
      s = (unsigned char *)OPENSSL_malloc((unsigned int)siglen);
      if (s == NULL) {
          RSAerr(RSA_F_INT_RSA_VERIFY, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      if ((dtype == NID_md5_sha1) && (m_len != SSL_SIG_LENGTH)) {
          RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_MESSAGE_LENGTH);
          goto err;
      }
      i = RSA_public_decrypt((int)siglen, sigbuf, s, rsa, RSA_PKCS1_PADDING);
  
      if (i <= 0)
          goto err;
      /*
       * Oddball MDC2 case: signature can be OCTET STRING. check for correct
       * tag and length octets.
       */
      if (dtype == NID_mdc2 && i == 18 && s[0] == 0x04 && s[1] == 0x10) {
          if (rm) {
              memcpy(rm, s + 2, 16);
              *prm_len = 16;
              ret = 1;
          } else if (memcmp(m, s + 2, 16)) {
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
          } else {
              ret = 1;
          }
      } else if (dtype == NID_md5_sha1) {
          /* Special case: SSL signature */
          if ((i != SSL_SIG_LENGTH) || memcmp(s, m, SSL_SIG_LENGTH))
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
          else
              ret = 1;
      } else {
          const unsigned char *p = s;
          sig = d2i_X509_SIG(NULL, &p, (long)i);
  
          if (sig == NULL)
              goto err;
  
          /* Excess data can be used to create forgeries */
          if (p != s + i || !rsa_check_digestinfo(sig, s, i)) {
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
              goto err;
          }
  
          /*
           * Parameters to the signature algorithm can also be used to create
           * forgeries
           */
          if (sig->algor->parameter
              && ASN1_TYPE_get(sig->algor->parameter) != V_ASN1_NULL) {
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
              goto err;
          }
  
          sigtype = OBJ_obj2nid(sig->algor->algorithm);
  
  #ifdef RSA_DEBUG
          /* put a backward compatibility flag in EAY */
          fprintf(stderr, "in(%s) expect(%s)\n", OBJ_nid2ln(sigtype),
                  OBJ_nid2ln(dtype));
  #endif
          if (sigtype != dtype) {
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_ALGORITHM_MISMATCH);
              goto err;
          }
          if (rm) {
              const EVP_MD *md;
              md = EVP_get_digestbynid(dtype);
              if (md && (EVP_MD_size(md) != sig->digest->length))
                  RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_INVALID_DIGEST_LENGTH);
              else {
                  memcpy(rm, sig->digest->data, sig->digest->length);
                  *prm_len = sig->digest->length;
                  ret = 1;
              }
          } else if (((unsigned int)sig->digest->length != m_len) ||
                     (memcmp(m, sig->digest->data, m_len) != 0)) {
              RSAerr(RSA_F_INT_RSA_VERIFY, RSA_R_BAD_SIGNATURE);
          } else
              ret = 1;
      }
   err:
      if (sig != NULL)
          X509_SIG_free(sig);
      if (s != NULL) {
          OPENSSL_cleanse(s, (unsigned int)siglen);
          OPENSSL_free(s);
      }
      return (ret);
  }
  
  int RSA_verify(int dtype, const unsigned char *m, unsigned int m_len,
                 const unsigned char *sigbuf, unsigned int siglen, RSA *rsa)
  {
  
      if ((rsa->meth->flags & RSA_FLAG_SIGN_VER) && rsa->meth->rsa_verify) {
          return rsa->meth->rsa_verify(dtype, m, m_len, sigbuf, siglen, rsa);
      }
  
      return int_rsa_verify(dtype, m, m_len, NULL, NULL, sigbuf, siglen, rsa);
  }
  