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Diffstat (limited to 'lib/nes/app/crypto/sha256.cc')
| -rw-r--r-- | lib/nes/app/crypto/sha256.cc | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/lib/nes/app/crypto/sha256.cc b/lib/nes/app/crypto/sha256.cc new file mode 100644 index 0000000..d8f8658 --- /dev/null +++ b/lib/nes/app/crypto/sha256.cc @@ -0,0 +1,156 @@ +#include "nes/app/crypto/sha256.hh" +#include "nes/common/utils.hh" + +namespace nes::app +{ + namespace + { + constexpr u32 round_constants[64] = + { + 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, + 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, + 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, + 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, + 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, + 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, + 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, + 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2, + }; + + auto rightrotate(u32 input, u32 index) -> u32 + { + return (input >> index) | (input << (32 - index)); + } + } // namespace + + auto sha256::get(u32 const index) -> u32 + { + auto const offset = index * 4; + return static_cast<u32>( + (data_[offset + 0] << 24) | + (data_[offset + 1] << 16) | + (data_[offset + 2] << 8) | + (data_[offset + 3] << 0)); + } + + auto sha256::set(u32 const index, u32 const value) -> void + { + auto const offset = index * 4; + data_[offset + 0] = static_cast<u8>((value >> 24) & 0xFF); + data_[offset + 1] = static_cast<u8>((value >> 16) & 0xFF); + data_[offset + 2] = static_cast<u8>((value >> 8) & 0xFF); + data_[offset + 3] = static_cast<u8>((value >> 0) & 0xFF); + } + + auto sha256::hash(span<u8 const> const message) -> sha256 + { + // https://en.wikipedia.org/wiki/SHA-2#Pseudocode + + auto res = sha256{}; + + auto const blocks = message.get_length() / block_size; + auto const remainder = message.get_length() - blocks * block_size; + for (auto i = u32{ 0 }; i < blocks; ++i) + { + res.combine(message.subspan<block_size>(i * block_size)); + } + + u8 last_blocks[block_size * 2]{}; + auto last_block_length = remainder; + copy(&message[blocks * block_size], last_blocks, remainder); + // Add a single 1 bit. + last_blocks[last_block_length++] = 0b10000000; + // Fill with 0 bits s.t. there's 8 bytes remaining in the last block. + auto zeroes = sizeof(last_blocks) - last_block_length - 8; + while (zeroes >= block_size) { zeroes -= block_size; } + last_block_length += zeroes; + // Add the length as big-endian. + auto const length = static_cast<u64>(message.get_length()) * 8; + last_blocks[last_block_length++] = static_cast<u8>((length >> 56) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 48) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 40) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 32) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 24) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 16) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 8) & 0xFF); + last_blocks[last_block_length++] = static_cast<u8>((length >> 0) & 0xFF); + auto const last_block_count = last_block_length / block_size; + for (auto i = u32{ 0 }; i < last_block_count; ++i) + { + res.combine(span<u8 const>(last_blocks).subspan<block_size>(i * block_size)); + } + + return res; + } + + sha256::sha256() + { + set(0, 0x6a09e667); + set(1, 0xbb67ae85); + set(2, 0x3c6ef372); + set(3, 0xa54ff53a); + set(4, 0x510e527f); + set(5, 0x9b05688c); + set(6, 0x1f83d9ab); + set(7, 0x5be0cd19); + } + + auto sha256::combine(span<u8 const, block_size> const chunk) -> void + { + u32 w[64]{}; + + // copy chunk into first 16 words w[0..15] of the message schedule array + for (auto i = u32{ 0 }; i < 16; ++i) + { + auto const offset = i * 4; + w[i] = static_cast<u32>( + (chunk[offset + 0] << 24) | + (chunk[offset + 1] << 16) | + (chunk[offset + 2] << 8) | + (chunk[offset + 3] << 0)); + } + + for (auto i = u32{ 16 }; i < 64; i++) + { + auto s0 = rightrotate(w[i-15], 7) ^ rightrotate(w[i-15], 18) ^ (w[i-15] >> 3); + auto s1 = rightrotate(w[i-2], 17) ^ rightrotate(w[i-2], 19) ^ (w[i-2] >> 10); + w[i] = w[i-16] + s0 + w[i-7] + s1; + } + auto a = get(0); + auto b = get(1); + auto c = get(2); + auto d = get(3); + auto e = get(4); + auto f = get(5); + auto g = get(6); + auto h = get(7); + + for (auto i = u32{ 0 }; i < 64; i++) + { + auto s1 = rightrotate(e, 6) ^ rightrotate(e, 11) ^ rightrotate(e, 25); + auto ch = (e & f) ^ ((~e) & g); + auto tmp1 = h + s1 + ch + round_constants[i] + w[i]; + auto s0 = rightrotate(a, 2) ^ rightrotate(a, 13) ^ rightrotate(a, 22); + auto maj = (a & b) ^ (a & c) ^ (b & c); + auto tmp2 = s0 + maj; + + h = g; + g = f; + f = e; + e = d + tmp1; + d = c; + c = b; + b = a; + a = tmp1 + tmp2; + } + + set(0, get(0) + a); + set(1, get(1) + b); + set(2, get(2) + c); + set(3, get(3) + d); + set(4, get(4) + e); + set(5, get(5) + f); + set(6, get(6) + g); + set(7, get(7) + h); + } +} // namespace nes::app
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