#include <openssl/rand.h>
#include <openssl/sha.h>
-int MGF1(unsigned char *mask, long len,
- const unsigned char *seed, long seedlen);
-
int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
const unsigned char *from, int flen,
const unsigned char *param, int plen)
{
+ return RSA_padding_add_PKCS1_OAEP_mgf1(to, tlen, from, flen,
+ param, plen, NULL, NULL);
+ }
+
+int RSA_padding_add_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
+ const unsigned char *from, int flen,
+ const unsigned char *param, int plen,
+ const EVP_MD *md, const EVP_MD *mgf1md)
+ {
int i, emlen = tlen - 1;
unsigned char *db, *seed;
- unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
+ unsigned char *dbmask, seedmask[EVP_MAX_MD_SIZE];
+ int mdlen;
+
+ if (md == NULL)
+ md = EVP_sha1();
+ if (mgf1md == NULL)
+ mgf1md = md;
- if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1)
+ mdlen = EVP_MD_size(md);
+
+ if (flen > emlen - 2 * mdlen - 1)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
+ RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1,
RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
- return (0);
+ return 0;
}
- if (emlen < 2 * SHA_DIGEST_LENGTH + 1)
- {
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL);
- return (0);
- }
-
- dbmask = OPENSSL_malloc(emlen - SHA_DIGEST_LENGTH);
- if (dbmask == NULL)
+ if (emlen < 2 * mdlen + 1)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
- return (0);
+ RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, RSA_R_KEY_SIZE_TOO_SMALL);
+ return 0;
}
to[0] = 0;
seed = to + 1;
- db = to + SHA_DIGEST_LENGTH + 1;
-
- EVP_Digest((void *)param, plen, db, NULL, EVP_sha1());
- memset(db + SHA_DIGEST_LENGTH, 0,
- emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
- db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
- memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
- if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0)
- return (0);
+ db = to + mdlen + 1;
+
+ if (!EVP_Digest((void *)param, plen, db, NULL, md, NULL))
+ return 0;
+ memset(db + mdlen, 0,
+ emlen - flen - 2 * mdlen - 1);
+ db[emlen - flen - mdlen - 1] = 0x01;
+ memcpy(db + emlen - flen - mdlen, from, (unsigned int) flen);
+ if (RAND_bytes(seed, mdlen) <= 0)
+ return 0;
#ifdef PKCS_TESTVECT
memcpy(seed,
"\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
20);
#endif
- MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
- for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
+ dbmask = OPENSSL_malloc(emlen - mdlen);
+ if (dbmask == NULL)
+ {
+ RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+
+ if (PKCS1_MGF1(dbmask, emlen - mdlen, seed, mdlen, mgf1md) < 0)
+ return 0;
+ for (i = 0; i < emlen - mdlen; i++)
db[i] ^= dbmask[i];
-
- MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
- for (i = 0; i < SHA_DIGEST_LENGTH; i++)
+
+ if (PKCS1_MGF1(seedmask, mdlen, db, emlen - mdlen, mgf1md) < 0)
+ return 0;
+ for (i = 0; i < mdlen; i++)
seed[i] ^= seedmask[i];
OPENSSL_free(dbmask);
const unsigned char *from, int flen, int num,
const unsigned char *param, int plen)
{
+ return RSA_padding_check_PKCS1_OAEP_mgf1(to, tlen, from , flen, num,
+ param, plen,
+ NULL, NULL);
+ }
+
+int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen,
+ const unsigned char *from, int flen, int num,
+ const unsigned char *param, int plen,
+ const EVP_MD *md, const EVP_MD *mgf1md)
+ {
int i, dblen, mlen = -1;
const unsigned char *maskeddb;
int lzero;
- unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+ unsigned char *db = NULL, seed[EVP_MAX_MD_SIZE], phash[EVP_MAX_MD_SIZE];
+ unsigned char *padded_from;
+ int bad = 0;
+ int mdlen;
- if (--num < 2 * SHA_DIGEST_LENGTH + 1)
+ if (md == NULL)
+ md = EVP_sha1();
+ if (mgf1md == NULL)
+ mgf1md = md;
+
+ mdlen = EVP_MD_size(md);
+
+ if (--num < 2 * mdlen + 1)
+ /* 'num' is the length of the modulus, i.e. does not depend on the
+ * particular ciphertext. */
goto decoding_err;
lzero = num - flen;
if (lzero < 0)
- goto decoding_err;
- maskeddb = from - lzero + SHA_DIGEST_LENGTH;
-
- dblen = num - SHA_DIGEST_LENGTH;
- db = OPENSSL_malloc(dblen);
+ {
+ /* signalling this error immediately after detection might allow
+ * for side-channel attacks (e.g. timing if 'plen' is huge
+ * -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal
+ * Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001),
+ * so we use a 'bad' flag */
+ bad = 1;
+ lzero = 0;
+ flen = num; /* don't overflow the memcpy to padded_from */
+ }
+
+ dblen = num - mdlen;
+ db = OPENSSL_malloc(dblen + num);
if (db == NULL)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
- return (-1);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, ERR_R_MALLOC_FAILURE);
+ return -1;
}
- MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
- for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
- seed[i] ^= from[i - lzero];
+ /* Always do this zero-padding copy (even when lzero == 0)
+ * to avoid leaking timing info about the value of lzero. */
+ padded_from = db + dblen;
+ memset(padded_from, 0, lzero);
+ memcpy(padded_from + lzero, from, flen);
+
+ maskeddb = padded_from + mdlen;
+
+ if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md))
+ return -1;
+ for (i = 0; i < mdlen; i++)
+ seed[i] ^= padded_from[i];
- MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
+ if (PKCS1_MGF1(db, dblen, seed, mdlen, mgf1md))
+ return -1;
for (i = 0; i < dblen; i++)
db[i] ^= maskeddb[i];
- EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1());
-
- if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
+ if (!EVP_Digest((void *)param, plen, phash, NULL, md, NULL))
+ return -1;
+
+ if (CRYPTO_memcmp(db, phash, mdlen) != 0 || bad)
goto decoding_err;
else
{
- for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
+ for (i = mdlen; i < dblen; i++)
if (db[i] != 0x00)
break;
- if (db[i] != 0x01 || i++ >= dblen)
+ if (i == dblen || db[i] != 0x01)
goto decoding_err;
else
{
- mlen = dblen - i;
+ /* everything looks OK */
+
+ mlen = dblen - ++i;
if (tlen < mlen)
{
- RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_DATA_TOO_LARGE);
mlen = -1;
}
else
}
OPENSSL_free(db);
return mlen;
-
+
decoding_err:
/* to avoid chosen ciphertext attacks, the error message should not reveal
* which kind of decoding error happened */
- RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP_MGF1, RSA_R_OAEP_DECODING_ERROR);
if (db != NULL) OPENSSL_free(db);
return -1;
}
-int MGF1(unsigned char *mask, long len,
- const unsigned char *seed, long seedlen)
+int PKCS1_MGF1(unsigned char *mask, long len,
+ const unsigned char *seed, long seedlen, const EVP_MD *dgst)
{
long i, outlen = 0;
unsigned char cnt[4];
EVP_MD_CTX c;
- unsigned char md[SHA_DIGEST_LENGTH];
+ unsigned char md[EVP_MAX_MD_SIZE];
+ int mdlen;
+ int rv = -1;
EVP_MD_CTX_init(&c);
+ mdlen = EVP_MD_size(dgst);
+ if (mdlen < 0)
+ goto err;
for (i = 0; outlen < len; i++)
{
cnt[0] = (unsigned char)((i >> 24) & 255);
cnt[1] = (unsigned char)((i >> 16) & 255);
cnt[2] = (unsigned char)((i >> 8)) & 255;
cnt[3] = (unsigned char)(i & 255);
- EVP_DigestInit(&c,EVP_sha1());
- EVP_DigestUpdate(&c, seed, seedlen);
- EVP_DigestUpdate(&c, cnt, 4);
- if (outlen + SHA_DIGEST_LENGTH <= len)
+ if (!EVP_DigestInit_ex(&c,dgst, NULL)
+ || !EVP_DigestUpdate(&c, seed, seedlen)
+ || !EVP_DigestUpdate(&c, cnt, 4))
+ goto err;
+ if (outlen + mdlen <= len)
{
- EVP_DigestFinal(&c, mask + outlen, NULL);
- outlen += SHA_DIGEST_LENGTH;
+ if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))
+ goto err;
+ outlen += mdlen;
}
else
{
- EVP_DigestFinal(&c, md, NULL);
+ if (!EVP_DigestFinal_ex(&c, md, NULL))
+ goto err;
memcpy(mask + outlen, md, len - outlen);
outlen = len;
}
}
+ rv = 0;
+ err:
EVP_MD_CTX_cleanup(&c);
- return 0;
+ return rv;
}
+
#endif
projects / oweals / openssl.git / blobdiff