/* ==================================================================== | |

* Copyright (c) 1998-2006 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). | |

* | |

* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) | |

* All rights reserved. | |

* | |

* This package is an SSL implementation written | |

* by Eric Young (eay@cryptsoft.com). | |

* The implementation was written so as to conform with Netscapes SSL. | |

* | |

* This library is free for commercial and non-commercial use as long as | |

* the following conditions are aheared to. The following conditions | |

* apply to all code found in this distribution, be it the RC4, RSA, | |

* lhash, DES, etc., code; not just the SSL code. The SSL documentation | |

* included with this distribution is covered by the same copyright terms | |

* except that the holder is Tim Hudson (tjh@cryptsoft.com). | |

* | |

* Copyright remains Eric Young's, and as such any Copyright notices in | |

* the code are not to be removed. | |

* If this package is used in a product, Eric Young should be given attribution | |

* as the author of the parts of the library used. | |

* This can be in the form of a textual message at program startup or | |

* in documentation (online or textual) provided with the package. | |

* | |

* 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 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 acknowledgement: | |

* "This product includes cryptographic software written by | |

* Eric Young (eay@cryptsoft.com)" | |

* The word 'cryptographic' can be left out if the rouines from the library | |

* being used are not cryptographic related :-). | |

* 4. If you include any Windows specific code (or a derivative thereof) from | |

* the apps directory (application code) you must include an acknowledgement: | |

* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |

* | |

* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND | |

* ANY EXPRESS 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 AUTHOR OR 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. | |

* | |

* The licence and distribution terms for any publically available version or | |

* derivative of this code cannot be changed. i.e. this code cannot simply be | |

* copied and put under another distribution licence | |

* [including the GNU Public Licence.] */ | |

#include <openssl/rsa.h> | |

#include <string.h> | |

#include <openssl/bn.h> | |

#include <openssl/mem.h> | |

#include <openssl/err.h> | |

#include "internal.h" | |

#include "../../internal.h" | |

#define BN_BLINDING_COUNTER 32 | |

struct bn_blinding_st { | |

BIGNUM *A; // The base blinding factor, Montgomery-encoded. | |

BIGNUM *Ai; // The inverse of the blinding factor, Montgomery-encoded. | |

unsigned counter; | |

}; | |

static int bn_blinding_create_param(BN_BLINDING *b, const BIGNUM *e, | |

const BN_MONT_CTX *mont, BN_CTX *ctx); | |

BN_BLINDING *BN_BLINDING_new(void) { | |

BN_BLINDING *ret = OPENSSL_zalloc(sizeof(BN_BLINDING)); | |

if (ret == NULL) { | |

return NULL; | |

} | |

ret->A = BN_new(); | |

if (ret->A == NULL) { | |

goto err; | |

} | |

ret->Ai = BN_new(); | |

if (ret->Ai == NULL) { | |

goto err; | |

} | |

// The blinding values need to be created before this blinding can be used. | |

ret->counter = BN_BLINDING_COUNTER - 1; | |

return ret; | |

err: | |

BN_BLINDING_free(ret); | |

return NULL; | |

} | |

void BN_BLINDING_free(BN_BLINDING *r) { | |

if (r == NULL) { | |

return; | |

} | |

BN_free(r->A); | |

BN_free(r->Ai); | |

OPENSSL_free(r); | |

} | |

void BN_BLINDING_invalidate(BN_BLINDING *b) { | |

b->counter = BN_BLINDING_COUNTER - 1; | |

} | |

static int bn_blinding_update(BN_BLINDING *b, const BIGNUM *e, | |

const BN_MONT_CTX *mont, BN_CTX *ctx) { | |

if (++b->counter == BN_BLINDING_COUNTER) { | |

// re-create blinding parameters | |

if (!bn_blinding_create_param(b, e, mont, ctx)) { | |

goto err; | |

} | |

b->counter = 0; | |

} else { | |

if (!BN_mod_mul_montgomery(b->A, b->A, b->A, mont, ctx) || | |

!BN_mod_mul_montgomery(b->Ai, b->Ai, b->Ai, mont, ctx)) { | |

goto err; | |

} | |

} | |

return 1; | |

err: | |

// |A| and |Ai| may be in an inconsistent state so they both need to be | |

// replaced the next time this blinding is used. Note that this is only | |

// sufficient because support for |BN_BLINDING_NO_UPDATE| and | |

// |BN_BLINDING_NO_RECREATE| was previously dropped. | |

b->counter = BN_BLINDING_COUNTER - 1; | |

return 0; | |

} | |

int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, const BIGNUM *e, | |

const BN_MONT_CTX *mont, BN_CTX *ctx) { | |

// |n| is not Montgomery-encoded and |b->A| is. |BN_mod_mul_montgomery| | |

// cancels one Montgomery factor, so the resulting value of |n| is unencoded. | |

if (!bn_blinding_update(b, e, mont, ctx) || | |

!BN_mod_mul_montgomery(n, n, b->A, mont, ctx)) { | |

return 0; | |

} | |

return 1; | |

} | |

int BN_BLINDING_invert(BIGNUM *n, const BN_BLINDING *b, BN_MONT_CTX *mont, | |

BN_CTX *ctx) { | |

// |n| is not Montgomery-encoded and |b->A| is. |BN_mod_mul_montgomery| | |

// cancels one Montgomery factor, so the resulting value of |n| is unencoded. | |

return BN_mod_mul_montgomery(n, n, b->Ai, mont, ctx); | |

} | |

static int bn_blinding_create_param(BN_BLINDING *b, const BIGNUM *e, | |

const BN_MONT_CTX *mont, BN_CTX *ctx) { | |

int no_inverse; | |

if (!BN_rand_range_ex(b->A, 1, &mont->N) || | |

// Compute |b->A|^-1 in Montgomery form. Note |BN_from_montgomery| + | |

// |BN_mod_inverse_blinded| is equivalent to, but more efficient than, | |

// |BN_mod_inverse_blinded| + |BN_to_montgomery|. | |

// | |

// We do not retry if |b->A| has no inverse. Finding a non-invertible | |

// value of |b->A| is equivalent to factoring |mont->N|. There is | |

// negligible probability of stumbling on one at random. | |

!BN_from_montgomery(b->Ai, b->A, mont, ctx) || | |

!BN_mod_inverse_blinded(b->Ai, &no_inverse, b->Ai, mont, ctx) || | |

// TODO(davidben): |BN_mod_exp_mont| internally computes the result in | |

// Montgomery form. Save a pair of Montgomery reductions and a | |

// multiplication by returning that value directly. | |

!BN_mod_exp_mont(b->A, b->A, e, &mont->N, ctx, mont) || | |

!BN_to_montgomery(b->A, b->A, mont, ctx)) { | |

OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR); | |

return 0; | |

} | |

return 1; | |

} |