f4b708cc1e
These empty states aren't any use to either caller or implementor. Change-Id: If0b748afeeb79e4a1386182e61c5b5ecf838de62 Reviewed-on: https://boringssl-review.googlesource.com/25254 Reviewed-by: Adam Langley <agl@google.com>
126 lines
4.1 KiB
C++
126 lines
4.1 KiB
C++
/* Copyright (c) 2017, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#include <openssl/bn.h>
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#include <openssl/bytestring.h>
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#include <openssl/mem.h>
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#define CHECK(expr) \
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do { \
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if (!(expr)) { \
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printf("%s failed\n", #expr); \
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abort(); \
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} \
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} while (false)
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// Basic implementation of mod_exp using square and multiple method.
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int mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
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BN_CTX *ctx) {
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if (BN_is_one(m)) {
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BN_zero(r);
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return 1;
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}
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bssl::UniquePtr<BIGNUM> exp(BN_dup(p));
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bssl::UniquePtr<BIGNUM> base(BN_new());
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if (!exp || !base) {
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return 0;
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}
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if (!BN_one(r) || !BN_nnmod(base.get(), a, m, ctx)) {
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return 0;
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}
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while (!BN_is_zero(exp.get())) {
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if (BN_is_odd(exp.get())) {
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if (!BN_mul(r, r, base.get(), ctx) || !BN_nnmod(r, r, m, ctx)) {
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return 0;
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}
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}
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if (!BN_rshift1(exp.get(), exp.get()) ||
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!BN_mul(base.get(), base.get(), base.get(), ctx) ||
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!BN_nnmod(base.get(), base.get(), m, ctx)) {
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return 0;
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}
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}
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return 1;
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}
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
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CBS cbs, child0, child1, child2;
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uint8_t sign;
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CBS_init(&cbs, buf, len);
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if (!CBS_get_u16_length_prefixed(&cbs, &child0) ||
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!CBS_get_u8(&child0, &sign) ||
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CBS_len(&child0) == 0 ||
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!CBS_get_u16_length_prefixed(&cbs, &child1) ||
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CBS_len(&child1) == 0 ||
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!CBS_get_u16_length_prefixed(&cbs, &child2) ||
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CBS_len(&child2) == 0) {
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return 0;
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}
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// Don't fuzz inputs larger than 512 bytes (4096 bits). This isn't ideal, but
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// the naive |mod_exp| above is somewhat slow, so this otherwise causes the
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// fuzzers to spend a lot of time exploring timeouts.
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if (CBS_len(&child0) > 512 ||
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CBS_len(&child1) > 512 ||
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CBS_len(&child2) > 512) {
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return 0;
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}
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bssl::UniquePtr<BIGNUM> base(
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BN_bin2bn(CBS_data(&child0), CBS_len(&child0), nullptr));
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BN_set_negative(base.get(), sign % 2);
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bssl::UniquePtr<BIGNUM> power(
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BN_bin2bn(CBS_data(&child1), CBS_len(&child1), nullptr));
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bssl::UniquePtr<BIGNUM> modulus(
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BN_bin2bn(CBS_data(&child2), CBS_len(&child2), nullptr));
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if (BN_is_zero(modulus.get())) {
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return 0;
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}
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bssl::UniquePtr<BN_CTX> ctx(BN_CTX_new());
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bssl::UniquePtr<BIGNUM> result(BN_new());
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bssl::UniquePtr<BIGNUM> expected(BN_new());
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CHECK(ctx);
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CHECK(result);
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CHECK(expected);
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CHECK(mod_exp(expected.get(), base.get(), power.get(), modulus.get(),
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ctx.get()));
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CHECK(BN_mod_exp(result.get(), base.get(), power.get(), modulus.get(),
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ctx.get()));
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CHECK(BN_cmp(result.get(), expected.get()) == 0);
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if (BN_is_odd(modulus.get())) {
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bssl::UniquePtr<BN_MONT_CTX> mont(
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BN_MONT_CTX_new_for_modulus(modulus.get(), ctx.get()));
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CHECK(mont);
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CHECK(BN_mod_exp_mont(result.get(), base.get(), power.get(), modulus.get(),
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ctx.get(), mont.get()));
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CHECK(BN_cmp(result.get(), expected.get()) == 0);
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CHECK(BN_mod_exp_mont_consttime(result.get(), base.get(), power.get(),
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modulus.get(), ctx.get(), mont.get()));
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CHECK(BN_cmp(result.get(), expected.get()) == 0);
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}
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uint8_t *data = (uint8_t *)OPENSSL_malloc(BN_num_bytes(result.get()));
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BN_bn2bin(result.get(), data);
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OPENSSL_free(data);
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return 0;
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}
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