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/*
* SEED
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/seed.h>
#include <botan/loadstor.h>
namespace Botan {
/*
* SEED G Function
*/
u32bit SEED::G_FUNC::operator()(u32bit X) const
{
return (S0[get_byte(3, X)] ^ S1[get_byte(2, X)] ^
S2[get_byte(1, X)] ^ S3[get_byte(0, X)]);
}
/*
* SEED Encryption
*/
void SEED::encrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit B0 = load_be<u32bit>(in, 0);
u32bit B1 = load_be<u32bit>(in, 1);
u32bit B2 = load_be<u32bit>(in, 2);
u32bit B3 = load_be<u32bit>(in, 3);
G_FUNC G;
for(size_t j = 0; j != 16; j += 2)
{
u32bit T0, T1;
T0 = B2 ^ K[2*j];
T1 = G(B2 ^ B3 ^ K[2*j+1]);
T0 = G(T1 + T0);
T1 = G(T1 + T0);
B1 ^= T1;
B0 ^= T0 + T1;
T0 = B0 ^ K[2*j+2];
T1 = G(B0 ^ B1 ^ K[2*j+3]);
T0 = G(T1 + T0);
T1 = G(T1 + T0);
B3 ^= T1;
B2 ^= T0 + T1;
}
store_be(out, B2, B3, B0, B1);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* SEED Decryption
*/
void SEED::decrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit B0 = load_be<u32bit>(in, 0);
u32bit B1 = load_be<u32bit>(in, 1);
u32bit B2 = load_be<u32bit>(in, 2);
u32bit B3 = load_be<u32bit>(in, 3);
G_FUNC G;
for(size_t j = 0; j != 16; j += 2)
{
u32bit T0, T1;
T0 = B2 ^ K[30-2*j];
T1 = G(B2 ^ B3 ^ K[31-2*j]);
T0 = G(T1 + T0);
T1 = G(T1 + T0);
B1 ^= T1;
B0 ^= T0 + T1;
T0 = B0 ^ K[28-2*j];
T1 = G(B0 ^ B1 ^ K[29-2*j]);
T0 = G(T1 + T0);
T1 = G(T1 + T0);
B3 ^= T1;
B2 ^= T0 + T1;
}
store_be(out, B2, B3, B0, B1);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* SEED Key Schedule
*/
void SEED::key_schedule(const byte key[], u32bit)
{
const u32bit RC[16] = {
0x9E3779B9, 0x3C6EF373, 0x78DDE6E6, 0xF1BBCDCC,
0xE3779B99, 0xC6EF3733, 0x8DDE6E67, 0x1BBCDCCF,
0x3779B99E, 0x6EF3733C, 0xDDE6E678, 0xBBCDCCF1,
0x779B99E3, 0xEF3733C6, 0xDE6E678D, 0xBCDCCF1B
};
SecureVector<u32bit> WK(4);
for(size_t i = 0; i != 4; ++i)
WK[i] = load_be<u32bit>(key, i);
G_FUNC G;
for(size_t i = 0; i != 16; i += 2)
{
K[2*i ] = G(WK[0] + WK[2] - RC[i]);
K[2*i+1] = G(WK[1] - WK[3] + RC[i]) ^ K[2*i];
byte T = get_byte(3, WK[0]);
WK[0] = (WK[0] >> 8) | (get_byte(3, WK[1]) << 24);
WK[1] = (WK[1] >> 8) | (T << 24);
K[2*i+2] = G(WK[0] + WK[2] - RC[i+1]);
K[2*i+3] = G(WK[1] - WK[3] + RC[i+1]) ^ K[2*i+2];
T = get_byte(0, WK[3]);
WK[3] = (WK[3] << 8) | get_byte(0, WK[2]);
WK[2] = (WK[2] << 8) | T;
}
}
}
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