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/**
* The Skein-512 hash function
* (C) 2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/skein_512.h>
#include <botan/loadstor.h>
#include <botan/parsing.h>
#include <algorithm>
#include <stdexcept>
namespace Botan {
namespace {
enum type_code {
SKEIN_KEY = 0,
SKEIN_CONFIG = 4,
SKEIN_PERSONALIZATION = 8,
SKEIN_PUBLIC_KEY = 12,
SKEIN_KEY_IDENTIFIER = 16,
SKEIN_NONCE = 20,
SKEIN_MSG = 48,
SKEIN_OUTPUT = 63
};
void ubi_512(u64bit H[9], u64bit T[], const byte msg[], u64bit msg_len)
{
bool first = true;
while(msg_len || first)
{
first = false;
const u64bit to_proc = std::min<u64bit>(msg_len, 64);
T[0] += to_proc;
u64bit M[8] = { 0 };
for(u32bit j = 0; j != to_proc / 8; ++j)
M[j] = load_le<u64bit>(msg, j);
if(to_proc % 8)
{
for(u32bit j = 0; j != to_proc % 8; ++j)
M[to_proc/8] |= ((u64bit)msg[8*(to_proc/8)+j] << (8*j));
}
H[8] = H[0] ^ H[1] ^ H[2] ^ H[3] ^
H[4] ^ H[5] ^ H[6] ^ H[7] ^ 0x5555555555555555;
T[2] = T[0] ^ T[1];
const u64bit K0 = H[0];
const u64bit K1 = H[1];
const u64bit K2 = H[2];
const u64bit K3 = H[3];
const u64bit K4 = H[4];
const u64bit K5 = H[5];
const u64bit K6 = H[6];
const u64bit K7 = H[7];
u64bit X0 = M[0] + K0;
u64bit X1 = M[1] + K1;
u64bit X2 = M[2] + K2;
u64bit X3 = M[3] + K3;
u64bit X4 = M[4] + K4;
u64bit X5 = M[5] + K5 + T[0];
u64bit X6 = M[6] + K6 + T[1];
u64bit X7 = M[7] + K7;
#define SKEIN_ROUND(I1,I2,I3,I4,I5,I6,I7,I8,ROT1,ROT2,ROT3,ROT4) \
do { \
X##I1 += X##I2; X##I2 = rotate_left(X##I2, ROT1) ^ X##I1; \
X##I3 += X##I4; X##I4 = rotate_left(X##I4, ROT2) ^ X##I3; \
X##I5 += X##I6; X##I6 = rotate_left(X##I6, ROT3) ^ X##I5; \
X##I7 += X##I8; X##I8 = rotate_left(X##I8, ROT4) ^ X##I7; \
} while(0);
#define SKEIN_INJECT_KEY(r) \
do { \
X0 += H[(r ) % 9]; \
X1 += H[(r+1) % 9]; \
X2 += H[(r+2) % 9]; \
X3 += H[(r+3) % 9]; \
X4 += H[(r+4) % 9]; \
X5 += H[(r+5) % 9] + T[(r ) % 3]; \
X6 += H[(r+6) % 9] + T[(r+1) % 3]; \
X7 += H[(r+7) % 9] + (r); \
} while(0);
#define SKEIN_8_ROUNDS(R1,R2) \
do { \
SKEIN_ROUND(0,1,2,3,4,5,6,7,38,30,50,53); \
SKEIN_ROUND(2,1,4,7,6,5,0,3,48,20,43,31); \
SKEIN_ROUND(4,1,6,3,0,5,2,7,34,14,15,27); \
SKEIN_ROUND(6,1,0,7,2,5,4,3,26,12,58, 7); \
\
SKEIN_INJECT_KEY(R1); \
\
SKEIN_ROUND(0,1,2,3,4,5,6,7,33,49, 8,42); \
SKEIN_ROUND(2,1,4,7,6,5,0,3,39,27,41,14); \
SKEIN_ROUND(4,1,6,3,0,5,2,7,29,26,11, 9); \
SKEIN_ROUND(6,1,0,7,2,5,4,3,33,51,39,35); \
\
SKEIN_INJECT_KEY(R2); \
} while(0);
SKEIN_8_ROUNDS(1,2);
SKEIN_8_ROUNDS(3,4);
SKEIN_8_ROUNDS(5,6);
SKEIN_8_ROUNDS(7,8);
SKEIN_8_ROUNDS(9,10);
SKEIN_8_ROUNDS(11,12);
SKEIN_8_ROUNDS(13,14);
SKEIN_8_ROUNDS(15,16);
SKEIN_8_ROUNDS(17,18);
// message feed forward
H[0] = X0 ^ M[0];
H[1] = X1 ^ M[1];
H[2] = X2 ^ M[2];
H[3] = X3 ^ M[3];
H[4] = X4 ^ M[4];
H[5] = X5 ^ M[5];
H[6] = X6 ^ M[6];
H[7] = X7 ^ M[7];
T[1] &= ~((u64bit)1 << 62); // clear first flag if set
msg_len -= to_proc;
msg += to_proc;
}
}
void reset_tweak(u64bit T[3], type_code type, bool final)
{
T[0] = 0;
T[1] = ((u64bit)type << 56) | ((u64bit)1 << 62) | ((u64bit)final << 63);
}
void initial_block(u64bit H[9], u64bit T[3], u32bit output_bits)
{
clear_mem(H, 9);
byte config_str[32] = { 0x53, 0x48, 0x41, 0x33, 0x01, 0x00, 0 };
store_le(output_bits, config_str + 8);
reset_tweak(T, SKEIN_CONFIG, true);
ubi_512(H, T, config_str, sizeof(config_str));
#if 0
if(personalization != "")
{
const byte* bits = reinterpret_cast<const byte*>(personalization.data());
// FIXME: will be wrong if personalization > 64 bytes b/c final
// bit is set for all blocks
reset_tweak(T, SKEIN_PERSONALIZATION, true);
ubi_512(H, T, bits, personalization.length());
}
#endif
reset_tweak(T, SKEIN_MSG, false);
}
}
Skein_512::Skein_512(u32bit arg_output_bits) :
HashFunction(arg_output_bits / 8, 64),
output_bits(arg_output_bits), buf_pos(0)
{
if(output_bits == 0 || output_bits % 8 != 0)
throw std::invalid_argument("Bad output bits size for Skein-512");
initial_block(H, T, output_bits);
}
std::string Skein_512::name() const
{
return "Skein-512(" + to_string(output_bits) + ")";
}
void Skein_512::clear() throw()
{
H.clear();
T.clear();
buffer.clear();
buf_pos = 0;
}
void Skein_512::add_data(const byte input[], u32bit length)
{
if(buf_pos)
{
buffer.copy(buf_pos, input, length);
if(buf_pos + length > 64)
{
ubi_512(H, T, &buffer[0], buffer.size());
input += (64 - buf_pos);
length -= (64 - buf_pos);
buf_pos = 0;
}
}
const u32bit full_blocks = (length - 1) / 64;
if(full_blocks)
ubi_512(H, T, input, 64*full_blocks);
length -= full_blocks * 64;
buffer.copy(buf_pos, input + full_blocks * 64, length);
buf_pos += length;
}
void Skein_512::final_result(byte out[])
{
T[1] |= ((u64bit)1 << 63); // final block flag
for(u32bit i = buf_pos; i != buffer.size(); ++i)
buffer[i] = 0;
ubi_512(H, T, &buffer[0], buf_pos);
byte counter[8] = { 0 };
u32bit out_bytes = output_bits / 8;
SecureBuffer<u64bit, 9> H_out;
while(out_bytes)
{
const u32bit to_proc = std::min<u32bit>(out_bytes, 64);
H_out.copy(H.begin(), 8);
reset_tweak(T, SKEIN_OUTPUT, true);
ubi_512(H_out, T, counter, sizeof(counter));
for(u32bit i = 0; i != to_proc; ++i)
out[i] = get_byte(7-i%8, H_out[i/8]);
out_bytes -= to_proc;
out += to_proc;
for(u32bit i = 0; i != sizeof(counter); ++i)
if(++counter[i])
break;
}
buf_pos = 0;
initial_block(H, T, output_bits);
}
}
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