Changes between 0.9.6i and 0.9.6j [xx XXX 2003]
- *)
+ *) Countermeasure against the Klima-Pokorny-Rosa extension of
+ Bleichbacher's attack on PKCS #1 v1.5 padding: treat
+ a protocol version number mismatch like a decryption error
+ in ssl3_get_client_key_exchange (ssl/s3_srvr.c).
+ [Bodo Moeller]
+
+ *) Turn on RSA blinding by default in the default implementation
+ to avoid a timing attack. Applications that don't want it can call
+ RSA_blinding_off() or use the new flag RSA_FLAG_NO_BLINDING.
+ They would be ill-advised to do so in most cases.
+ [Ben Laurie, Steve Henson, Geoff Thorpe]
+
+ *) Change RSA blinding code so that it works when the PRNG is not
+ seeded (in this case, the secret RSA exponent is abused as
+ an unpredictable seed -- if it is not unpredictable, there
+ is no point in blinding anyway).
+ [Bodo Moeller]
Changes between 0.9.6h and 0.9.6i [19 Feb 2003]
the OpenSSH configure script. It should contain the detailed information
on why the OpenSSL library was not detected or considered incompatible.
+
* Can I use OpenSSL's SSL library with non-blocking I/O?
Yes; make sure to read the SSL_get_error(3) manual page!
---------------
/* ====================================================================
- * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
+ * Copyright (c) 1998-2003 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
#define RSA_FLAG_CACHE_PUBLIC 0x02
#define RSA_FLAG_CACHE_PRIVATE 0x04
#define RSA_FLAG_BLINDING 0x08
+#define RSA_FLAG_NO_BLINDING 0x80 /* new with 0.9.6j and 0.9.7b; the built-in
+ * RSA implementation now uses blinding by
+ * default (ignoring RSA_FLAG_BLINDING),
+ * but other engines might not need it
+ */
#define RSA_FLAG_THREAD_SAFE 0x10
/* This flag means the private key operations will be handled by rsa_mod_exp
* and that they do not depend on the private key components being present:
*/
#define RSA_FLAG_SIGN_VER 0x40
+#define RSA_FLAG_NO_BLINDING 0x80
+
#define RSA_PKCS1_PADDING 1
#define RSA_SSLV23_PADDING 2
#define RSA_NO_PADDING 3
return(r);
}
+static int rsa_eay_blinding(RSA *rsa, BN_CTX *ctx)
+ {
+ int ret = 1;
+ CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+ /* Check again inside the lock - the macro's check is racey */
+ if(rsa->blinding == NULL)
+ ret = RSA_blinding_on(rsa, ctx);
+ CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
+ return ret;
+ }
+
+#define BLINDING_HELPER(rsa, ctx, err_instr) \
+ do { \
+ if((!((rsa)->flags & RSA_FLAG_NO_BLINDING)) && \
+ ((rsa)->blinding == NULL) && \
+ !rsa_eay_blinding(rsa, ctx)) \
+ err_instr \
+ } while(0)
+
/* signing */
static int RSA_eay_private_encrypt(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding)
goto err;
}
- if ((rsa->flags & RSA_FLAG_BLINDING) && (rsa->blinding == NULL))
- RSA_blinding_on(rsa,ctx);
- if (rsa->flags & RSA_FLAG_BLINDING)
+ BLINDING_HELPER(rsa, ctx, goto err;);
+
+ if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
if (!meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,NULL)) goto err;
}
- if (rsa->flags & RSA_FLAG_BLINDING)
+ if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_invert(&ret,rsa->blinding,ctx)) goto err;
/* put in leading 0 bytes if the number is less than the
goto err;
}
- if ((rsa->flags & RSA_FLAG_BLINDING) && (rsa->blinding == NULL))
- RSA_blinding_on(rsa,ctx);
- if (rsa->flags & RSA_FLAG_BLINDING)
+ BLINDING_HELPER(rsa, ctx, goto err;);
+
+ if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_convert(&f,rsa->blinding,ctx)) goto err;
/* do the decrypt */
goto err;
}
- if (rsa->flags & RSA_FLAG_BLINDING)
+ if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
if (!BN_BLINDING_invert(&ret,rsa->blinding,ctx)) goto err;
p=buf;
RSA *RSA_new(void)
{
- return(RSA_new_method(NULL));
+ RSA *r=RSA_new_method(NULL);
+
+ return r;
}
void RSA_set_default_openssl_method(RSA_METHOD *meth)
BN_BLINDING_free(rsa->blinding);
rsa->blinding=NULL;
}
- rsa->flags&= ~RSA_FLAG_BLINDING;
+ rsa->flags &= ~RSA_FLAG_BLINDING;
+ rsa->flags |= RSA_FLAG_NO_BLINDING;
}
int RSA_blinding_on(RSA *rsa, BN_CTX *p_ctx)
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
- if (!BN_rand_range(A,rsa->n)) goto err;
+ if ((RAND_status() == 0) && rsa->d != NULL && rsa->d->d != NULL)
+ {
+ /* if PRNG is not properly seeded, resort to secret exponent as unpredictable seed */
+ RAND_add(rsa->d->d, rsa->d->dmax * sizeof rsa->d->d[0], 0);
+ if (!BN_pseudo_rand_range(A,rsa->n)) goto err;
+ }
+ else
+ {
+ if (!BN_rand_range(A,rsa->n)) goto err;
+ }
if ((Ai=BN_mod_inverse(NULL,A,rsa->n,ctx)) == NULL) goto err;
if (!ENGINE_get_RSA(rsa->engine)->bn_mod_exp(A,A,
rsa->e,rsa->n,ctx,rsa->_method_mod_n))
goto err;
rsa->blinding=BN_BLINDING_new(A,Ai,rsa->n);
- rsa->flags|=RSA_FLAG_BLINDING;
+ rsa->flags |= RSA_FLAG_BLINDING;
+ rsa->flags &= ~RSA_FLAG_NO_BLINDING;
BN_free(Ai);
ret=1;
err:
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))))
(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. */
}
}
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=
projects / oweals / openssl.git / commitdiff