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when checking OAEP, signal just a single kind of 'decoding error'

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This commit is contained in:
Bodo Möller 2001-06-06 18:48:49 +00:00
parent 8ca2ae775d
commit 20e021bf41
1 changed files with 11 additions and 10 deletions
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21
crypto/rsa/rsa_oaep.c
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@ -94,20 +94,14 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
int i, dblen, mlen = -1; int i, dblen, mlen = -1;
const unsigned char *maskeddb; const unsigned char *maskeddb;
int lzero; 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) if (--num < 2 * SHA_DIGEST_LENGTH + 1)
{ goto decoding_err;
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
return (-1);
}
lzero = num - flen; lzero = num - flen;
if (lzero < 0) if (lzero < 0)
{ goto decoding_err;
RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
return (-1);
}
maskeddb = from - lzero + SHA_DIGEST_LENGTH; maskeddb = from - lzero + SHA_DIGEST_LENGTH;
dblen = num - SHA_DIGEST_LENGTH; dblen = num - SHA_DIGEST_LENGTH;
@ -129,7 +123,7 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
SHA1(param, plen, phash); SHA1(param, plen, phash);
if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0) 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 else
{ {
for (i = SHA_DIGEST_LENGTH; i < dblen; i++) for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
@ -152,6 +146,13 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
} }
OPENSSL_free(db); OPENSSL_free(db);
return (mlen); 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, int MGF1(unsigned char *mask, long len,