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/**
This code is licensed under the MCGSI Public License
Copyright 2018 Jeff Becker
Kovri go write your own code
*/
#ifndef LIBI2PD_POLY1305_H
#define LIBI2PD_POLY1305_H
#include <cstdint>
#include <cstring>
#include "Crypto.h"
#if LEGACY_OPENSSL
namespace i2p
{
namespace crypto
{
const std::size_t POLY1305_DIGEST_BYTES = 16;
const std::size_t POLY1305_DIGEST_DWORDS = 4;
const std::size_t POLY1305_KEY_BYTES = 32;
const std::size_t POLY1305_KEY_DWORDS = 8;
const std::size_t POLY1305_BLOCK_BYTES = 16;
namespace poly1305
{
struct LongBlock
{
unsigned long data[17];
operator unsigned long * ()
{
return data;
}
};
struct Block
{
unsigned char data[17];
void Zero()
{
memset(data, 0, sizeof(data));
}
operator uint8_t * ()
{
return data;
}
Block & operator += (const Block & other)
{
unsigned short u;
unsigned int i;
for(u = 0, i = 0; i < 17; i++)
{
u += (unsigned short) data[i] + (unsigned short) other.data[i];
data[i] = (unsigned char) u & 0xff;
u >>= 8;
}
return *this;
}
Block & operator %=(const LongBlock & other)
{
unsigned long u;
unsigned int i;
u = 0;
for (i = 0; i < 16; i++) {
u += other.data[i];
data[i] = (unsigned char)u & 0xff;
u >>= 8;
}
u += other.data[16];
data[16] = (unsigned char)u & 0x03;
u >>= 2;
u += (u << 2);
for (i = 0; i < 16; i++) {
u += data[i];
data[i] = (unsigned char)u & 0xff;
u >>= 8;
}
data[16] += (unsigned char)u;
return *this;
}
Block & operator = (const Block & other)
{
memcpy(data, other.data, sizeof(data));
return *this;
}
Block & operator ~ ()
{
static const Block minusp = {
0x05,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0xfc
};
Block orig;
unsigned char neg;
unsigned int i;
orig = *this;
*this += minusp;
neg = -(data[16] >> 7);
for(i = 0; i < 17; i++)
data[i] ^= neg & (orig.data[i] ^ data[i]);
return *this;
}
void PutKey(const uint64_t * key_l)
{
const uint8_t * key = (const uint8_t*) key_l;
data[0] = key[0] & 0xff;
data[1] = key[1] & 0xff;
data[2] = key[2] & 0xff;
data[3] = key[3] & 0x0f;
data[4] = key[4] & 0xfc;
data[5] = key[5] & 0xff;
data[6] = key[6] & 0xff;
data[7] = key[7] & 0x0f;
data[8] = key[8] & 0xfc;
data[9] = key[9] & 0xff;
data[10] = key[10] & 0xff;
data[11] = key[11] & 0x0f;
data[12] = key[12] & 0xfc;
data[13] = key[13] & 0xff;
data[14] = key[14] & 0xff;
data[15] = key[15] & 0x0f;
data[16] = 0;
}
template<typename Int_t>
void Put(const Int_t * d, uint8_t last=0)
{
memcpy(data, d, 16);
data[16] = last;
}
};
struct Buffer
{
uint8_t data[POLY1305_BLOCK_BYTES];
operator uint8_t * ()
{
return data;
}
};
}
struct Poly1305
{
Poly1305(const uint64_t * key)
{
m_Leftover = 0;
m_H.Zero();
m_Final = 0;
m_R.PutKey(key);
m_Pad.Put(key + 2);
}
void Update(const uint8_t * buf, size_t sz)
{
// process leftover
if(m_Leftover)
{
size_t want = POLY1305_BLOCK_BYTES - m_Leftover;
if(want > sz) want = sz;
memcpy(m_Buffer + m_Leftover, buf, want);
sz -= want;
buf += want;
m_Leftover += want;
if(m_Leftover < POLY1305_BLOCK_BYTES) return;
Blocks(m_Buffer, POLY1305_BLOCK_BYTES);
m_Leftover = 0;
}
// process blocks
if(sz >= POLY1305_BLOCK_BYTES)
{
size_t want = (sz & ~(POLY1305_BLOCK_BYTES - 1));
Blocks(buf, want);
buf += want;
sz -= want;
}
// leftover
if(sz)
{
memcpy(m_Buffer+m_Leftover, buf, sz);
m_Leftover += sz;
}
}
void Blocks(const uint8_t * buf, size_t sz)
{
const unsigned char hi = m_Final ^ 1;
while (sz >= POLY1305_BLOCK_BYTES) {
unsigned long u;
unsigned int i, j;
m_Msg.Put(buf, hi);
/* h += m */
m_H += m_Msg;
/* h *= r */
for (i = 0; i < 17; i++) {
u = 0;
for (j = 0; j <= i ; j++) {
u += (unsigned short)m_H.data[j] * m_R.data[i - j];
}
for (j = i + 1; j < 17; j++) {
unsigned long v = (unsigned short)m_H.data[j] * m_R.data[i + 17 - j];
v = ((v << 8) + (v << 6)); /* v *= (5 << 6); */
u += v;
}
m_HR[i] = u;
}
/* (partial) h %= p */
m_H %= m_HR;
buf += POLY1305_BLOCK_BYTES;
sz -= POLY1305_BLOCK_BYTES;
}
}
void Finish(uint64_t * out)
{
// process leftovers
if(m_Leftover)
{
size_t idx = m_Leftover;
m_Buffer[idx++] = 1;
for(; idx < POLY1305_BLOCK_BYTES; idx++)
m_Buffer[idx] = 0;
m_Final = 1;
Blocks(m_Buffer, POLY1305_BLOCK_BYTES);
}
// freeze H
~m_H;
// add pad
m_H += m_Pad;
// copy digest
memcpy(out, m_H, 16);
}
size_t m_Leftover;
poly1305::Buffer m_Buffer;
poly1305::Block m_H;
poly1305::Block m_R;
poly1305::Block m_Pad;
poly1305::Block m_Msg;
poly1305::LongBlock m_HR;
uint8_t m_Final;
};
void Poly1305HMAC(uint64_t * out, const uint64_t * key, const uint8_t * buf, std::size_t sz);
}
}
#endif
#endif