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OpenSSL Security Advisory [19 March 2003] 

Klima-Pokorny-Rosa attack on RSA in SSL/TLS
This commit is contained in:
itojun 2003-03-19 23:06:33 +00:00
parent aa70f03b23
commit 359e4b88f5
1 changed files with 12 additions and 13 deletions
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25
crypto/dist/openssl/ssl/s3_srvr.c vendored
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@ -1418,7 +1418,7 @@ static int ssl3_get_client_key_exchange(SSL *s)
if (i != SSL_MAX_MASTER_KEY_LENGTH)
{
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT);
/* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_RSA_DECRYPT); */
}
if ((al == -1) && !((p[0] == (s->client_version>>8)) && (p[1] == (s->client_version & 0xff))))
@ -1434,30 +1434,29 @@ static int ssl3_get_client_key_exchange(SSL *s)
(p[0] == (s->version>>8)) && (p[1] == (s->version & 0xff))))
{
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
goto f_err;
/* SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,SSL_R_BAD_PROTOCOL_VERSION_NUMBER); */
/* The Klima-Pokorny-Rosa extension of Bleichenbacher's attack
* (http://eprint.iacr.org/2003/052/) exploits the version
* number check as a "bad version oracle" -- an alert would
* reveal that the plaintext corresponding to some ciphertext
* made up by the adversary is properly formatted except
* that the version number is wrong. To avoid such attacks,
* we should treat this just like any other decryption error. */
p[0] = (char)(int) "CAN-2003-0131 patch 2003-03-19";
}
}
if (al != -1)
{
#if 0
goto f_err;
#else
/* Some decryption failure -- use random value instead as countermeasure
* against Bleichenbacher's attack on PKCS #1 v1.5 RSA padding
* (see RFC 2246, section 7.4.7.1).
* But note that due to length and protocol version checking, the
* attack is impractical anyway (see section 5 in D. Bleichenbacher:
* "Chosen Ciphertext Attacks Against Protocols Based on the RSA
* Encryption Standard PKCS #1", CRYPTO '98, LNCS 1462, pp. 1-12).
*/
* (see RFC 2246, section 7.4.7.1). */
ERR_clear_error();
i = SSL_MAX_MASTER_KEY_LENGTH;
p[0] = s->client_version >> 8;
p[1] = s->client_version & 0xff;
RAND_pseudo_bytes(p+2, i-2); /* should be RAND_bytes, but we cannot work around a failure */
#endif
}
s->session->master_key_length=