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/*************************************************
* SAFER-SK Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/safer_sk.h>
#include <botan/bit_ops.h>
#include <botan/parsing.h>
namespace Botan {
/*************************************************
* SAFER-SK Encryption *
*************************************************/
void SAFER_SK::enc(const byte in[], byte out[]) const
{
byte A = in[0], B = in[1], C = in[2], D = in[3],
E = in[4], F = in[5], G = in[6], H = in[7], X, Y;
for(u32bit j = 0; j != 16*ROUNDS; j += 16)
{
A = EXP[A ^ EK[j ]]; B = LOG[B + EK[j+1]];
C = LOG[C + EK[j+2]]; D = EXP[D ^ EK[j+3]];
E = EXP[E ^ EK[j+4]]; F = LOG[F + EK[j+5]];
G = LOG[G + EK[j+6]]; H = EXP[H ^ EK[j+7]];
A += EK[j+ 8]; B ^= EK[j+ 9]; C ^= EK[j+10]; D += EK[j+11];
E += EK[j+12]; F ^= EK[j+13]; G ^= EK[j+14]; H += EK[j+15];
B += A; D += C; F += E; H += G; A += B; C += D; E += F; G += H;
C += A; G += E; D += B; H += F; A += C; E += G; B += D; F += H;
H += D; Y = D + H; D = B + F; X = B + D; B = A + E;
A += B; F = C + G; E = C + F; C = X; G = Y;
}
out[0] = A ^ EK[16*ROUNDS+0]; out[1] = B + EK[16*ROUNDS+1];
out[2] = C + EK[16*ROUNDS+2]; out[3] = D ^ EK[16*ROUNDS+3];
out[4] = E ^ EK[16*ROUNDS+4]; out[5] = F + EK[16*ROUNDS+5];
out[6] = G + EK[16*ROUNDS+6]; out[7] = H ^ EK[16*ROUNDS+7];
}
/*************************************************
* SAFER-SK Decryption *
*************************************************/
void SAFER_SK::dec(const byte in[], byte out[]) const
{
byte A = in[0], B = in[1], C = in[2], D = in[3],
E = in[4], F = in[5], G = in[6], H = in[7];
A ^= EK[16*ROUNDS+0]; B -= EK[16*ROUNDS+1]; C -= EK[16*ROUNDS+2];
D ^= EK[16*ROUNDS+3]; E ^= EK[16*ROUNDS+4]; F -= EK[16*ROUNDS+5];
G -= EK[16*ROUNDS+6]; H ^= EK[16*ROUNDS+7];
for(s32bit j = 16*(ROUNDS-1); j >= 0; j -= 16)
{
byte T = E; E = B; B = C; C = T; T = F; F = D; D = G; G = T;
A -= E; B -= F; C -= G; D -= H; E -= A; F -= B; G -= C; H -= D;
A -= C; E -= G; B -= D; F -= H; C -= A; G -= E; D -= B; H -= F;
A -= B; C -= D; E -= F; G -= H; B -= A; D -= C; F -= E; H -= G;
A = LOG[A - EK[j+8 ] + 256]; B = EXP[B ^ EK[j+9 ]];
C = EXP[C ^ EK[j+10]]; D = LOG[D - EK[j+11] + 256];
E = LOG[E - EK[j+12] + 256]; F = EXP[F ^ EK[j+13]];
G = EXP[G ^ EK[j+14]]; H = LOG[H - EK[j+15] + 256];
A ^= EK[j+0]; B -= EK[j+1]; C -= EK[j+2]; D ^= EK[j+3];
E ^= EK[j+4]; F -= EK[j+5]; G -= EK[j+6]; H ^= EK[j+7];
}
out[0] = A; out[1] = B; out[2] = C; out[3] = D;
out[4] = E; out[5] = F; out[6] = G; out[7] = H;
}
/*************************************************
* SAFER-SK Key Schedule *
*************************************************/
void SAFER_SK::key(const byte key[], u32bit)
{
SecureBuffer<byte, 18> KB;
for(u32bit j = 0; j != 8; ++j)
{
KB[ 8] ^= KB[j] = rotate_left(key[j], 5);
KB[17] ^= KB[j+9] = EK[j] = key[j+8];
}
for(u32bit j = 0; j != ROUNDS; ++j)
{
for(u32bit k = 0; k != 18; ++k)
KB[k] = rotate_left(KB[k], 6);
for(u32bit k = 0; k != 16; ++k)
EK[16*j+k+8] = KB[KEY_INDEX[16*j+k]] + BIAS[16*j+k];
}
}
/*************************************************
* Return the name of this type *
*************************************************/
std::string SAFER_SK::name() const
{
return "SAFER-SK(" + to_string(ROUNDS) + ")";
}
/*************************************************
* Return a clone of this object *
*************************************************/
BlockCipher* SAFER_SK::clone() const
{
return new SAFER_SK(ROUNDS);
}
/*************************************************
* SAFER-SK Constructor *
*************************************************/
SAFER_SK::SAFER_SK(u32bit rounds) : BlockCipher(8, 16),
EK(16 * rounds + 8), ROUNDS(rounds)
{
if(ROUNDS > 13 || ROUNDS == 0)
throw Invalid_Argument(name() + ": Invalid number of rounds");
}
}
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