seed = to + 1;
db = to + SHA_DIGEST_LENGTH + 1;
- EVP_Digest((void *)param, plen, db, NULL, EVP_sha1());
+ EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL);
memset(db + SHA_DIGEST_LENGTH, 0,
emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
const unsigned char *maskeddb;
int lzero;
unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+ unsigned char *padded_from;
int bad = 0;
if (--num < 2 * SHA_DIGEST_LENGTH + 1)
lzero = num - flen;
if (lzero < 0)
{
- /* lzero == -1 */
-
/* 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
* so we use a 'bad' flag */
bad = 1;
lzero = 0;
+ flen = num; /* don't overflow the memcpy to padded_from */
}
- maskeddb = from - lzero + SHA_DIGEST_LENGTH;
dblen = num - SHA_DIGEST_LENGTH;
- db = OPENSSL_malloc(dblen);
+ db = OPENSSL_malloc(dblen + num);
if (db == NULL)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
return -1;
}
+ /* 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 + SHA_DIGEST_LENGTH;
+
MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
- for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
- seed[i] ^= from[i - lzero];
+ for (i = 0; i < SHA_DIGEST_LENGTH; i++)
+ seed[i] ^= padded_from[i];
MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
for (i = 0; i < dblen; i++)
db[i] ^= maskeddb[i];
- EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1());
+ EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL);
if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
goto decoding_err;
for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
if (db[i] != 0x00)
break;
- if (db[i] != 0x01 || i++ >= dblen)
+ if (i == dblen || db[i] != 0x01)
goto decoding_err;
else
{
/* everything looks OK */
- mlen = dblen - i;
+ mlen = dblen - ++i;
if (tlen < mlen)
{
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
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;
EVP_MD_CTX_init(&c);
+ mdlen = M_EVP_MD_size(dgst);
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_DigestInit_ex(&c,dgst, NULL);
EVP_DigestUpdate(&c, seed, seedlen);
EVP_DigestUpdate(&c, cnt, 4);
- if (outlen + SHA_DIGEST_LENGTH <= len)
+ if (outlen + mdlen <= len)
{
- EVP_DigestFinal(&c, mask + outlen, NULL);
- outlen += SHA_DIGEST_LENGTH;
+ EVP_DigestFinal_ex(&c, mask + outlen, NULL);
+ outlen += mdlen;
}
else
{
- EVP_DigestFinal(&c, md, NULL);
+ EVP_DigestFinal_ex(&c, md, NULL);
memcpy(mask + outlen, md, len - outlen);
outlen = len;
}
EVP_MD_CTX_cleanup(&c);
return 0;
}
+
+int MGF1(unsigned char *mask, long len, const unsigned char *seed, long seedlen)
+ {
+ return PKCS1_MGF1(mask, len, seed, seedlen, EVP_sha1());
+ }
#endif