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) */
7 #if !defined(NO_SHA) && !defined(NO_SHA1)
10 #include <openssl/bn.h>
11 #include <openssl/rsa.h>
12 #include <openssl/sha.h>
13 #include <openssl/rand.h>
15 int MGF1(unsigned char *mask, long len,
16 const unsigned char *seed, long seedlen);
18 int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
19 const unsigned char *from, int flen,
20 const unsigned char *param, int plen)
22 int i, emlen = tlen - 1;
23 unsigned char *db, *seed;
24 unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
26 if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1)
28 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
29 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
33 if (emlen < 2 * SHA_DIGEST_LENGTH + 1)
35 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL);
39 dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH);
42 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
48 db = to + SHA_DIGEST_LENGTH + 1;
50 SHA1(param, plen, db);
51 memset(db + SHA_DIGEST_LENGTH, 0,
52 emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
53 db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
54 memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
55 if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0)
59 "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
63 MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
64 for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
67 MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
68 for (i = 0; i < SHA_DIGEST_LENGTH; i++)
69 seed[i] ^= seedmask[i];
75 int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
76 const unsigned char *from, int flen, int num,
77 const unsigned char *param, int plen)
79 int i, dblen, mlen = -1;
80 const unsigned char *maskeddb;
82 unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
84 if (--num < 2 * SHA_DIGEST_LENGTH + 1)
86 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
90 dblen = num - SHA_DIGEST_LENGTH;
91 db = OPENSSL_malloc(dblen);
94 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
99 maskeddb = from - lzero + SHA_DIGEST_LENGTH;
101 MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
102 for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
103 seed[i] ^= from[i - lzero];
105 MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
106 for (i = 0; i < dblen; i++)
107 db[i] ^= maskeddb[i];
109 SHA1(param, plen, phash);
111 if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
112 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
115 for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
118 if (db[i] != 0x01 || i++ >= dblen)
119 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
120 RSA_R_OAEP_DECODING_ERROR);
126 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
130 memcpy(to, db + i, mlen);
137 int MGF1(unsigned char *mask, long len,
138 const unsigned char *seed, long seedlen)
141 unsigned char cnt[4];
143 unsigned char md[SHA_DIGEST_LENGTH];
145 for (i = 0; outlen < len; i++)
147 cnt[0] = (i >> 24) & 255, cnt[1] = (i >> 16) & 255,
148 cnt[2] = (i >> 8) & 255, cnt[3] = i & 255;
150 SHA1_Update(&c, seed, seedlen);
151 SHA1_Update(&c, cnt, 4);
152 if (outlen + SHA_DIGEST_LENGTH <= len)
154 SHA1_Final(mask + outlen, &c);
155 outlen += SHA_DIGEST_LENGTH;
160 memcpy(mask + outlen, md, len - outlen);