diff options
| -rw-r--r-- | src/fuzzer/pow_mod.cpp | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/src/fuzzer/pow_mod.cpp b/src/fuzzer/pow_mod.cpp index e74902bd9..0151609fd 100644 --- a/src/fuzzer/pow_mod.cpp +++ b/src/fuzzer/pow_mod.cpp @@ -1,5 +1,5 @@ /* -* (C) 2016 Jack Lloyd +* (C) 2016,2018 Jack Lloyd * * Botan is released under the Simplified BSD License (see license.txt) */ @@ -13,8 +13,7 @@ namespace { Botan::BigInt simple_power_mod(Botan::BigInt x, Botan::BigInt n, - const Botan::BigInt& p, - const Botan::Modular_Reducer& mod_p) + const Botan::BigInt& p) { if(n == 0) { @@ -23,6 +22,7 @@ Botan::BigInt simple_power_mod(Botan::BigInt x, return 1; } + Botan::Modular_Reducer mod_p(p); Botan::BigInt y = 1; while(n > 1) @@ -41,19 +41,23 @@ Botan::BigInt simple_power_mod(Botan::BigInt x, void fuzz(const uint8_t in[], size_t len) { - static const size_t p_bits = 1024; - static const Botan::BigInt p = random_prime(fuzzer_rng(), p_bits); - static Botan::Modular_Reducer mod_p(p); + static const size_t max_bits = 2048; - if(len == 0 || len > p_bits/8) + if(len % 3 != 0) return; + const size_t part_size = len / 3; + + if(part_size * 8 > max_bits) + return; + + const Botan::BigInt g = Botan::BigInt::decode(in, part_size); + const Botan::BigInt x = Botan::BigInt::decode(in + part_size, part_size); + const Botan::BigInt p = Botan::BigInt::decode(in + 2*part_size, part_size); + try { - const Botan::BigInt g = Botan::BigInt::decode(in, len / 2); - const Botan::BigInt x = Botan::BigInt::decode(in + len / 2, len / 2); - - const Botan::BigInt ref = simple_power_mod(g, x, p, mod_p); + const Botan::BigInt ref = simple_power_mod(g, x, p); const Botan::BigInt z = Botan::power_mod(g, x, p); if(ref != z) |