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correct chacha20 for multiple messages

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orignal 2018-11-30 16:21:11 -05:00
parent e68f1dbc99
commit ef6db64e9f
4 changed files with 81 additions and 58 deletions
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48
libi2pd/ChaCha20.cpp
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@ -15,9 +15,6 @@ namespace crypto
{
namespace chacha
{
constexpr int rounds = 20;
constexpr std::size_t blocksize = 64;
void u32t8le(uint32_t v, uint8_t * p)
{
p[0] = v & 0xff;
@ -51,22 +48,14 @@ void quarterround(uint32_t *x, int a, int b, int c, int d)
}
struct Block_t
{
Block_t() {};
Block_t(Block_t &&) = delete;
uint8_t data[blocksize];
void operator << (const Chacha20State & st)
void Chacha20Block::operator << (const Chacha20State & st)
{
int i;
for (i = 0; i < 16; i++)
u32t8le(st.data[i], data + (i << 2));
}
};
void block(const Chacha20State &input, Block_t & block, int rounds)
void block (Chacha20State &input, int rounds)
{
int i;
Chacha20State x;
@ -84,10 +73,9 @@ void block(const Chacha20State &input, Block_t & block, int rounds)
quarterround(x.data, 3, 4, 9, 14);
}
x += input;
block << x;
input.block << x;
}
} // namespace chacha
void Chacha20Init (Chacha20State& state, const uint8_t * nonce, const uint8_t * key, uint32_t counter)
{
@ -105,24 +93,40 @@ void block(const Chacha20State &input, Block_t & block, int rounds)
void Chacha20Encrypt (Chacha20State& state, uint8_t * buf, size_t sz)
{
chacha::Block_t block;
if (state.offset > 0)
{
// previous block if any
auto s = chacha::blocksize - state.offset;
if (sz < s) s = sz;
for (size_t i = 0; i < s; i++)
buf[i] ^= state.block.data[state.offset + i];
buf += s;
sz -= s;
state.offset = 0;
}
for (size_t i = 0; i < sz; i += chacha::blocksize)
{
chacha::block(state, block, chacha::rounds);
chacha::block(state, chacha::rounds);
state.data[12]++;
for (size_t j = i; j < i + chacha::blocksize; j++)
{
if (j >= sz) break;
buf[j] ^= block.data[j - i];
if (j >= sz)
{
state.offset = j & 0x3F; // % 64
break;
}
buf[j] ^= state.block.data[j - i];
}
}
}
} // namespace chacha
void chacha20(uint8_t * buf, size_t sz, const uint8_t * nonce, const uint8_t * key, uint32_t counter)
{
Chacha20State state;
Chacha20Init (state, nonce, key, counter);
Chacha20Encrypt (state, buf, sz);
chacha::Chacha20State state;
chacha::Chacha20Init (state, nonce, key, counter);
chacha::Chacha20Encrypt (state, buf, sz);
}
}
}

21
libi2pd/ChaCha20.h
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@ -21,9 +21,25 @@ namespace crypto
const std::size_t CHACHA20_KEY_BYTES = 32;
const std::size_t CHACHA20_NOUNCE_BYTES = 12;
namespace chacha
{
constexpr std::size_t blocksize = 64;
constexpr int rounds = 20;
struct Chacha20State;
struct Chacha20Block
{
Chacha20Block () {};
Chacha20Block (Chacha20Block &&) = delete;
uint8_t data[blocksize];
void operator << (const Chacha20State & st);
};
struct Chacha20State
{
Chacha20State () {};
Chacha20State (): offset (0) {};
Chacha20State (Chacha20State &&) = delete;
Chacha20State & operator += (const Chacha20State & other)
@ -38,10 +54,13 @@ namespace crypto
memcpy(data, other.data, sizeof(uint32_t) * 16);
}
uint32_t data[16];
Chacha20Block block;
size_t offset;
};
void Chacha20Init (Chacha20State& state, const uint8_t * nonce, const uint8_t * key, uint32_t counter);
void Chacha20Encrypt (Chacha20State& state, uint8_t * buf, size_t sz);
}
/** encrypt buf in place with chacha20 */
void chacha20(uint8_t * buf, size_t sz, const uint8_t * nonce, const uint8_t * key, uint32_t counter=1);

6
libi2pd/Crypto.cpp
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@ -1182,12 +1182,12 @@ namespace crypto
chacha20 ((uint8_t *)polyKey, 64, nonce, key, 0);
Poly1305 polyHash (polyKey);
// encrypt buffers
Chacha20State state;
Chacha20Init (state, nonce, key, 1);
chacha::Chacha20State state;
chacha::Chacha20Init (state, nonce, key, 1);
size_t size = 0;
for (auto& it: bufs)
{
Chacha20Encrypt (state, (uint8_t *)it.first, it.second);
chacha::Chacha20Encrypt (state, (uint8_t *)it.first, it.second);
polyHash.Update ((uint8_t *)it.first, it.second); // after encryption
size += it.second;
}

2
tests/test-aeadchacha20poly1305.cpp
View File

@ -53,7 +53,7 @@ int main ()
assert (memcmp (buf1, text, 114) == 0);
// test encryption of multiple buffers
memcpy (buf, text, 114);
std::vector<std::pair<void*, std::size_t> > bufs{ std::make_pair (buf, 114) };
std::vector<std::pair<void*, std::size_t> > bufs{ std::make_pair (buf, 50), std::make_pair (buf + 50, 50), std::make_pair (buf + 100, 14) };
i2p::crypto::AEADChaCha20Poly1305Encrypt (bufs, key, nonce, buf + 114);
i2p::crypto::AEADChaCha20Poly1305 (buf, 114, nullptr, 0, key, nonce, buf1, 114, false);
assert (memcmp (buf1, text, 114) == 0);