int i, dblen, mlen = -1;
unsigned char *maskeddb;
int lzero;
- unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+ unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
if (--num < 2 * SHA_DIGEST_LENGTH + 1)
- {
- RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
- return (-1);
- }
+ 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);
if (db == NULL)
return (-1);
}
- lzero = num - flen;
- maskeddb = from - lzero + SHA_DIGEST_LENGTH;
-
MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
seed[i] ^= from[i - lzero];
SHA1(param, plen, phash);
if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
- RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+ goto decoding_err;
else
{
for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
if (db[i] != 0x00)
break;
if (db[i] != 0x01 || i++ >= dblen)
- RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
- RSA_R_OAEP_DECODING_ERROR);
+ goto decoding_err;
else
{
mlen = dblen - i;
if (tlen < mlen)
{
- RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, 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);
+ if (db != NULL) OPENSSL_free(db);
+ return -1;
}
int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen)