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I2P: End-to-End encrypted and anonymous Internet
https://i2pd.website/
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138 lines
3.0 KiB
138 lines
3.0 KiB
/* |
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* Copyright (c) 2013-2018, The PurpleI2P Project |
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* |
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* This file is part of Purple i2pd project and licensed under BSD3 |
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* |
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* See full license text in LICENSE file at top of project tree |
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* |
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* Kovri go write your own code |
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* |
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*/ |
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#include "I2PEndian.h" |
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#include "ChaCha20.h" |
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#if !OPENSSL_AEAD_CHACHA20_POLY1305 |
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namespace i2p |
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{ |
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namespace crypto |
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{ |
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namespace chacha |
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{ |
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void u32t8le(uint32_t v, uint8_t * p) |
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{ |
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p[0] = v & 0xff; |
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p[1] = (v >> 8) & 0xff; |
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p[2] = (v >> 16) & 0xff; |
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p[3] = (v >> 24) & 0xff; |
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} |
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uint32_t u8t32le(const uint8_t * p) |
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{ |
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uint32_t value = p[3]; |
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value = (value << 8) | p[2]; |
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value = (value << 8) | p[1]; |
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value = (value << 8) | p[0]; |
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return value; |
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} |
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uint32_t rotl32(uint32_t x, int n) |
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{ |
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return x << n | (x >> (-n & 31)); |
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} |
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void quarterround(uint32_t *x, int a, int b, int c, int d) |
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{ |
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x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 16); |
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x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 12); |
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x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 8); |
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x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 7); |
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} |
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void Chacha20Block::operator << (const Chacha20State & st) |
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{ |
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int i; |
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for (i = 0; i < 16; i++) |
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u32t8le(st.data[i], data + (i << 2)); |
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} |
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void block (Chacha20State &input, int rounds) |
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{ |
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int i; |
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Chacha20State x; |
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x.Copy(input); |
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for (i = rounds; i > 0; i -= 2) |
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{ |
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quarterround(x.data, 0, 4, 8, 12); |
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quarterround(x.data, 1, 5, 9, 13); |
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quarterround(x.data, 2, 6, 10, 14); |
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quarterround(x.data, 3, 7, 11, 15); |
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quarterround(x.data, 0, 5, 10, 15); |
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quarterround(x.data, 1, 6, 11, 12); |
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quarterround(x.data, 2, 7, 8, 13); |
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quarterround(x.data, 3, 4, 9, 14); |
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} |
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x += input; |
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input.block << x; |
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} |
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void Chacha20Init (Chacha20State& state, const uint8_t * nonce, const uint8_t * key, uint32_t counter) |
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{ |
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state.data[0] = 0x61707865; |
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state.data[1] = 0x3320646e; |
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state.data[2] = 0x79622d32; |
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state.data[3] = 0x6b206574; |
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for (size_t i = 0; i < 8; i++) |
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state.data[4 + i] = chacha::u8t32le(key + i * 4); |
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state.data[12] = htole32 (counter); |
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for (size_t i = 0; i < 3; i++) |
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state.data[13 + i] = chacha::u8t32le(nonce + i * 4); |
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} |
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void Chacha20SetCounter (Chacha20State& state, uint32_t counter) |
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{ |
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state.data[12] = htole32 (counter); |
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state.offset = 0; |
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} |
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void Chacha20Encrypt (Chacha20State& state, uint8_t * buf, size_t sz) |
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{ |
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if (state.offset > 0) |
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{ |
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// previous block if any |
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auto s = chacha::blocksize - state.offset; |
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if (sz < s) s = sz; |
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for (size_t i = 0; i < s; i++) |
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buf[i] ^= state.block.data[state.offset + i]; |
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buf += s; |
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sz -= s; |
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state.offset += s; |
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if (state.offset >= chacha::blocksize) state.offset = 0; |
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} |
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for (size_t i = 0; i < sz; i += chacha::blocksize) |
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{ |
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chacha::block(state, chacha::rounds); |
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state.data[12]++; |
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for (size_t j = i; j < i + chacha::blocksize; j++) |
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{ |
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if (j >= sz) |
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{ |
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state.offset = j & 0x3F; // % 64 |
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break; |
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} |
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buf[j] ^= state.block.data[j - i]; |
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} |
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} |
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} |
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} // namespace chacha |
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} |
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} |
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#endif |
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