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. */
5 /* EME_OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
14 int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen);
16 int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
17 unsigned char *from, int flen, unsigned char *param, int plen)
19 int i, emlen = tlen - 1;
20 unsigned char *db, *seed;
21 unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
23 if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1)
25 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
26 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
30 if (emlen < 2 * SHA_DIGEST_LENGTH + 1)
32 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL);
36 dbmask = Malloc(emlen - SHA_DIGEST_LENGTH);
39 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
45 db = to + SHA_DIGEST_LENGTH + 1;
47 SHA1(param, plen, db);
48 memset(db + SHA_DIGEST_LENGTH, 0,
49 emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
50 db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
51 memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
52 RAND_bytes(seed, SHA_DIGEST_LENGTH);
55 "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
59 MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
60 for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
63 MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
64 for (i = 0; i < SHA_DIGEST_LENGTH; i++)
65 seed[i] ^= seedmask[i];
71 int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
72 unsigned char *from, int flen, int num, unsigned char *param,
75 int i, dblen, mlen = -1;
76 unsigned char *maskeddb;
77 unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
79 if (flen < 2 * SHA_DIGEST_LENGTH + 1)
81 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
85 dblen = flen - SHA_DIGEST_LENGTH;
89 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
93 maskeddb = from + SHA_DIGEST_LENGTH;
95 MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
96 for (i = 0; i < SHA_DIGEST_LENGTH; i++)
99 MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
100 for (i = 0; i < dblen; i++)
101 db[i] ^= maskeddb[i];
103 SHA1(param, plen, phash);
105 if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
106 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
109 for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
112 if (db[i] != 0x01 || i++ >= dblen)
113 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
114 RSA_R_OAEP_DECODING_ERROR);
120 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
124 memcpy(to, db + i, mlen);
131 int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen)
134 unsigned char cnt[4];
136 unsigned char md[SHA_DIGEST_LENGTH];
138 for (i = 0; outlen < len; i++)
140 cnt[0] = (i >> 24) & 255, cnt[1] = (i >> 16) & 255,
141 cnt[2] = (i >> 8) & 255, cnt[3] = i & 255;
143 SHA1_Update(&c, seed, seedlen);
144 SHA1_Update(&c, cnt, 4);
145 if (outlen + SHA_DIGEST_LENGTH <= len)
147 SHA1_Final(mask + outlen, &c);
148 outlen += SHA_DIGEST_LENGTH;
153 memcpy(mask + outlen, md, len - outlen);