diff options
author | Bodo Möller <bodo@openssl.org> | 2005-05-16 01:43:31 +0000 |
---|---|---|
committer | Bodo Möller <bodo@openssl.org> | 2005-05-16 01:43:31 +0000 |
commit | 46a643763de6d8e39ecf6f76fa79b4d04885aa59 (patch) | |
tree | e1f3cfc98bddba797b5300977dbf3223f008fc4a /crypto/rsa/rsa_eay.c | |
parent | 92c44685724c0d993ea8920577680f3c0a1d79c8 (diff) |
Implement fixed-window exponentiation to mitigate hyper-threading
timing attacks.
BN_FLG_EXP_CONSTTIME requests this algorithm, and this done by default for
RSA/DSA/DH private key computations unless
RSA_FLAG_NO_EXP_CONSTTIME/DSA_FLAG_NO_EXP_CONSTTIME/
DH_FLAG_NO_EXP_CONSTTIME is set.
Submitted by: Matthew D Wood
Reviewed by: Bodo Moeller
Diffstat (limited to 'crypto/rsa/rsa_eay.c')
-rw-r--r-- | crypto/rsa/rsa_eay.c | 127 |
1 files changed, 118 insertions, 9 deletions
diff --git a/crypto/rsa/rsa_eay.c b/crypto/rsa/rsa_eay.c index 21755c0e2f..175ab8a789 100644 --- a/crypto/rsa/rsa_eay.c +++ b/crypto/rsa/rsa_eay.c @@ -55,6 +55,59 @@ * copied and put under another distribution licence * [including the GNU Public Licence.] */ +/* ==================================================================== + * Copyright (c) 1998-2005 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 + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * 3. All advertising materials mentioning features or use of this + * software must display the following acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" + * + * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to + * endorse or promote products derived from this software without + * prior written permission. For written permission, please contact + * openssl-core@openssl.org. + * + * 5. Products derived from this software may not be called "OpenSSL" + * nor may "OpenSSL" appear in their names without prior written + * permission of the OpenSSL Project. + * + * 6. Redistributions of any form whatsoever must retain the following + * acknowledgment: + * "This product includes software developed by the OpenSSL Project + * for use in the OpenSSL Toolkit (http://www.openssl.org/)" + * + * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY + * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR + * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * ==================================================================== + * + * This product includes cryptographic software written by Eric Young + * (eay@cryptsoft.com). This product includes software written by Tim + * Hudson (tjh@cryptsoft.com). + * + */ #include <stdio.h> #include "cryptlib.h" @@ -320,11 +373,25 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from, (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL)) ) - { if (!rsa->meth->rsa_mod_exp(ret,f,rsa,ctx)) goto err; } + { + if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) goto err; + } else { + BIGNUM local_d; + BIGNUM *d = NULL; + + if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME)) + { + d = &local_d; + BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME); + } + else + d = rsa->d; + MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err); - if (!rsa->meth->bn_mod_exp(ret,f,rsa->d,rsa->n,ctx, + + if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx, rsa->_method_mod_n)) goto err; } @@ -416,13 +483,26 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from, (rsa->dmp1 != NULL) && (rsa->dmq1 != NULL) && (rsa->iqmp != NULL)) ) - { if (!rsa->meth->rsa_mod_exp(ret,f,rsa,ctx)) goto err; } + { + if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) goto err; + } else { + BIGNUM local_d; + BIGNUM *d = NULL; + + if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME)) + { + d = &local_d; + BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME); + } + else + d = rsa->d; + MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err); - if (!rsa->meth->bn_mod_exp(ret,f,rsa->d,rsa->n,ctx, + if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx, rsa->_method_mod_n)) - goto err; + goto err; } if (blinding) @@ -547,6 +627,8 @@ err: static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) { BIGNUM *r1,*m1,*vrfy; + BIGNUM local_dmp1, local_dmq1; + BIGNUM *dmp1, *dmq1; int ret=0; BN_CTX_start(ctx); @@ -559,11 +641,25 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err); if (!BN_mod(r1,I,rsa->q,ctx)) goto err; - if (!rsa->meth->bn_mod_exp(m1,r1,rsa->dmq1,rsa->q,ctx, + if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME)) + { + dmq1 = &local_dmq1; + BN_with_flags(dmq1, rsa->dmq1, BN_FLG_EXP_CONSTTIME); + } + else + dmq1 = rsa->dmq1; + if (!rsa->meth->bn_mod_exp(m1,r1,dmq1,rsa->q,ctx, rsa->_method_mod_q)) goto err; if (!BN_mod(r1,I,rsa->p,ctx)) goto err; - if (!rsa->meth->bn_mod_exp(r0,r1,rsa->dmp1,rsa->p,ctx, + if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME)) + { + dmp1 = &local_dmp1; + BN_with_flags(dmp1, rsa->dmp1, BN_FLG_EXP_CONSTTIME); + } + else + dmp1 = rsa->dmp1; + if (!rsa->meth->bn_mod_exp(r0,r1,dmp1,rsa->p,ctx, rsa->_method_mod_p)) goto err; if (!BN_sub(r0,r0,m1)) goto err; @@ -598,11 +694,24 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) if (BN_is_negative(vrfy)) if (!BN_add(vrfy, vrfy, rsa->n)) goto err; if (!BN_is_zero(vrfy)) + { /* 'I' and 'vrfy' aren't congruent mod n. Don't leak * miscalculated CRT output, just do a raw (slower) * mod_exp and return that instead. */ - if (!rsa->meth->bn_mod_exp(r0,I,rsa->d,rsa->n,ctx, - rsa->_method_mod_n)) goto err; + + BIGNUM local_d; + BIGNUM *d = NULL; + + if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME)) + { + d = &local_d; + BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME); + } + else + d = rsa->d; + if (!rsa->meth->bn_mod_exp(r0,I,d,rsa->n,ctx, + rsa->_method_mod_n)) goto err; + } } ret=1; err: |