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March 24, 2018 01:38
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Chacha20 encryption
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| /* | |
| Base32.hpp -- Chacha20 encryption | |
| Copyright 2018 yni3 | |
| License : Public Domain | |
| */ | |
| #pragma once | |
| #ifndef __CHACHA20 | |
| #define __CHACHA20 | |
| class ChaCha20 { | |
| typedef char s8; | |
| typedef int s32; | |
| typedef unsigned long long u64; | |
| typedef unsigned int u32; | |
| typedef unsigned char u8; | |
| void memcpy(u8* dist, const u8* src, size_t n) | |
| { | |
| unsigned char* ss1 = dist; | |
| const unsigned char* ss2 = src; | |
| const unsigned char* end = src + n; | |
| while (src != end) | |
| *dist++ = *src++; | |
| } | |
| void zeromemcpy(u8* dist, size_t n) | |
| { | |
| unsigned char* ss1 = dist; | |
| const unsigned char* end = dist + n; | |
| while (dist != end) | |
| *dist++ = 0; | |
| } | |
| static constexpr u32 rotl32(const u32 &x, s32 n) { | |
| return (x << n) | (x >> (-n & 31)); | |
| } | |
| static constexpr u32 ReadLE32(const u8 *a) { | |
| return | |
| u32(a[0] << 0 * 8) | | |
| u32(a[1] << 1 * 8) | | |
| u32(a[2] << 2 * 8) | | |
| u32(a[3] << 3 * 8); | |
| } | |
| static void WriteLE32(u8* dst, const u32 &src) { | |
| dst[0] = (src >> 0 * 8) & 0xff; | |
| dst[1] = (src >> 1 * 8) & 0xff; | |
| dst[2] = (src >> 2 * 8) & 0xff; | |
| dst[3] = (src >> 3 * 8) & 0xff; | |
| } | |
| void Init(const u8 key[32], const u8 nonce[8]) { | |
| const u8 *magic_constant = (u8*)"expand 32-byte k"; | |
| state[0] = ReadLE32(magic_constant + 0 * 4); | |
| state[1] = ReadLE32(magic_constant + 1 * 4); | |
| state[2] = ReadLE32(magic_constant + 2 * 4); | |
| state[3] = ReadLE32(magic_constant + 3 * 4); | |
| state[4] = ReadLE32(key + 0 * 4); | |
| state[5] = ReadLE32(key + 1 * 4); | |
| state[6] = ReadLE32(key + 2 * 4); | |
| state[7] = ReadLE32(key + 3 * 4); | |
| state[8] = ReadLE32(key + 4 * 4); | |
| state[9] = ReadLE32(key + 5 * 4); | |
| state[10] = ReadLE32(key + 6 * 4); | |
| state[11] = ReadLE32(key + 7 * 4); | |
| state[12] = 0; | |
| state[13] = 0; | |
| state[14] = ReadLE32(nonce + 0 * 4); | |
| state[15] = ReadLE32(nonce + 1 * 4); | |
| } | |
| void seek(u64 counter) { | |
| state[12] = static_cast<u32>(counter); | |
| state[13] = static_cast<u32>(counter >> 32); | |
| } | |
| static inline void QUARTERROUND(unsigned int *x, const int a, const int b, const int c, const int d) | |
| { | |
| x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 16); | |
| x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 12); | |
| x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 8); | |
| x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 7); | |
| } | |
| void next(u32 out[16]) { | |
| for (int i = 0; i < 16; i++) out[i] = state[i]; | |
| for (int i = 0; i < 10; i++) { | |
| QUARTERROUND(out, 0, 4, 8, 12); | |
| QUARTERROUND(out, 1, 5, 9, 13); | |
| QUARTERROUND(out, 2, 6, 10, 14); | |
| QUARTERROUND(out, 3, 7, 11, 15); | |
| QUARTERROUND(out, 0, 5, 10, 15); | |
| QUARTERROUND(out, 1, 6, 11, 12); | |
| QUARTERROUND(out, 2, 7, 8, 13); | |
| QUARTERROUND(out, 3, 4, 9, 14); | |
| } | |
| for (int i = 0; i < 16; i++) out[i] += state[i]; | |
| //update state | |
| state[12] = state[12] + 1; | |
| if (state[12] == 0) { state[13] = state[13] + 1; } | |
| } | |
| u32 state[16]; | |
| u32 keystream32[16]; | |
| size_t position; | |
| public: | |
| ChaCha20( | |
| const s8* key, | |
| s32 size, | |
| u64 counter = 0 | |
| ) : position(64) { | |
| u8 keybuff[32]; | |
| u8 noncebuff[8]; | |
| zeromemcpy(keybuff, 32); | |
| zeromemcpy(noncebuff, 8); | |
| for (s32 i = 0; i < size && i < 32; i++) { | |
| keybuff[i] = key[i]; | |
| } | |
| Init(keybuff, noncebuff); | |
| seek(counter); | |
| } | |
| ChaCha20( | |
| const s8* key, | |
| s32 skey, | |
| const s8* nonce, | |
| s32 snonce, | |
| u64 counter = 0 | |
| ) : position(64) { | |
| u8 keybuff[32]; | |
| u8 noncebuff[8]; | |
| zeromemcpy(keybuff, 32); | |
| zeromemcpy(noncebuff, 8); | |
| for (s32 i = 0; i < 32 && i < skey; i++) { | |
| keybuff[i] = key[i]; | |
| } | |
| for (s32 i = 0; i < 8 && i < snonce; i++) { | |
| noncebuff[i] = nonce[i]; | |
| } | |
| Init(keybuff, noncebuff); | |
| seek(counter); | |
| } | |
| ChaCha20() : position(64) { | |
| zeromemcpy(reinterpret_cast<u8*>(&state), sizeof(u32) * 16); | |
| zeromemcpy(reinterpret_cast<u8*>(&keystream32), sizeof(u32) * 16); | |
| } | |
| void setPassWrod(const s8* key,s32 size, u64 counter = 0) { | |
| u8 keybuff[32]; | |
| u8 noncebuff[8]; | |
| zeromemcpy(keybuff, 32); | |
| zeromemcpy(noncebuff, 8); | |
| for (s32 i = 0; i < size; i++) { | |
| keybuff[i] = key[i]; | |
| } | |
| Init(keybuff, noncebuff); | |
| seek(counter); | |
| } | |
| //encryption | |
| void crypt(u8 *bytes, size_t n_bytes) { | |
| u8 blk[64]; | |
| u8 *keystream8 = (u8*)keystream32; | |
| for (size_t i = 0; i < n_bytes; i++) { | |
| if (position >= 64) { | |
| next(keystream32); | |
| position = 0; | |
| } | |
| for (s32 j = 0; j < 16; ++j) { WriteLE32(blk + (4 * i), keystream32[i]); } | |
| bytes[i] ^= blk[position]; | |
| position++; | |
| } | |
| } | |
| //encryption | |
| void update(u8 *dst, const u8 *src, s32 srclen) { | |
| memcpy(dst, src, srclen); | |
| crypt(dst, srclen); | |
| } | |
| }; | |
| #endif |
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