crypto/rsa/rsa_oaep.c

   1 /* crypto/rsa/rsa_oaep.c */
   2 /* Written by Ulf Moeller. This software is distributed on an "AS IS"
   3    basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */
   4
   5 /* EME_OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
   6
   7 #if !defined(NO_SHA) && !defined(NO_SHA1)
   8 #include <stdio.h>
   9 #include "cryptlib.h"
  10 #include <openssl/bn.h>
  11 #include <openssl/rsa.h>
  12 #include <openssl/sha.h>
  13 #include <openssl/rand.h>
  14
  15 int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen);
  16
  17 int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
  18              unsigned char *from, int flen, unsigned char *param, int plen)
  19     {
  20     int i, emlen = tlen - 1;
  21     unsigned char *db, *seed;
  22     unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
  23
  24     if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1)
  25         {
  26         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
  27                RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
  28         return (0);
  29         }
  30
  31     if (emlen < 2 * SHA_DIGEST_LENGTH + 1)
  32         {
  33         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL);
  34         return (0);
  35         }
  36
  37     dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH);
  38     if (dbmask == NULL)
  39         {
  40         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
  41         return (0);
  42         }
  43
  44     to[0] = 0;
  45     seed = to + 1;
  46     db = to + SHA_DIGEST_LENGTH + 1;
  47
  48     SHA1(param, plen, db);
  49     memset(db + SHA_DIGEST_LENGTH, 0,
  50            emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
  51     db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
  52     memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
  53     if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0)
  54         return (0);
  55 #ifdef PKCS_TESTVECT
  56     memcpy(seed,
  57            "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
  58            20);
  59 #endif
  60
  61     MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
  62     for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
  63         db[i] ^= dbmask[i];
  64
  65     MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
  66     for (i = 0; i < SHA_DIGEST_LENGTH; i++)
  67         seed[i] ^= seedmask[i];
  68
  69     OPENSSL_free(dbmask);
  70     return (1);
  71     }
  72
  73 int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
  74              unsigned char *from, int flen, int num, unsigned char *param,
  75              int plen)
  76     {
  77     int i, dblen, mlen = -1;
  78     unsigned char *maskeddb;
  79     int lzero;
  80     unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
  81
  82     if (--num < 2 * SHA_DIGEST_LENGTH + 1)
  83         {
  84         RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
  85         return (-1);
  86         }
  87
  88     dblen = num - SHA_DIGEST_LENGTH;
  89     db = OPENSSL_malloc(dblen);
  90     if (db == NULL)
  91         {
  92         RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
  93         return (-1);
  94         }
  95
  96     lzero = num - flen;
  97     maskeddb = from - lzero + SHA_DIGEST_LENGTH;
  98
  99     MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
 100     for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
 101         seed[i] ^= from[i - lzero];
 102
 103     MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
 104     for (i = 0; i < dblen; i++)
 105         db[i] ^= maskeddb[i];
 106
 107     SHA1(param, plen, phash);
 108
 109     if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
 110         RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
 111     else
 112         {
 113         for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
 114             if (db[i] != 0x00)
 115                 break;
 116         if (db[i] != 0x01 || i++ >= dblen)
 117             RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
 118                    RSA_R_OAEP_DECODING_ERROR);
 119         else
 120             {
 121             mlen = dblen - i;
 122             if (tlen < mlen)
 123                 {
 124                 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
 125                 mlen = -1;
 126                 }
 127             else
 128                 memcpy(to, db + i, mlen);
 129             }
 130         }
 131     OPENSSL_free(db);
 132     return (mlen);
 133     }
 134
 135 int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen)
 136     {
 137     long i, outlen = 0;
 138     unsigned char cnt[4];
 139     SHA_CTX c;
 140     unsigned char md[SHA_DIGEST_LENGTH];
 141
 142     for (i = 0; outlen < len; i++)
 143         {
 144         cnt[0] = (i >> 24) & 255, cnt[1] = (i >> 16) & 255,
 145           cnt[2] = (i >> 8) & 255, cnt[3] = i & 255;
 146         SHA1_Init(&c);
 147         SHA1_Update(&c, seed, seedlen);
 148         SHA1_Update(&c, cnt, 4);
 149         if (outlen + SHA_DIGEST_LENGTH <= len)
 150             {
 151             SHA1_Final(mask + outlen, &c);
 152             outlen += SHA_DIGEST_LENGTH;
 153             }
 154         else
 155             {
 156             SHA1_Final(md, &c);
 157             memcpy(mask + outlen, md, len - outlen);
 158             outlen = len;
 159             }
 160         }
 161     return (0);
 162     }
 163 #endif