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/*************************************************
* KASUMI Source File *
* (C) 1999-2007 The Botan Project *
*************************************************/
#include <botan/kasumi.h>
#include <botan/loadstor.h>
#include <botan/bit_ops.h>
namespace Botan {
namespace {
/*************************************************
* KASUMI FI Function *
*************************************************/
u16bit FI(u16bit I, u16bit K)
{
u16bit D9 = (I >> 7);
byte D7 = (I & 0x7F);
D9 = KASUMI_SBOX_S9[D9] ^ D7;
D7 = KASUMI_SBOX_S7[D7] ^ (D9 & 0x7F);
D7 ^= (K >> 9);
D9 = KASUMI_SBOX_S9[D9 ^ (K & 0x1FF)] ^ D7;
D7 = KASUMI_SBOX_S7[D7] ^ (D9 & 0x7F);
return (D7 << 9) | D9;
}
}
/*************************************************
* KASUMI Encryption *
*************************************************/
void KASUMI::enc(const byte in[], byte out[]) const
{
u16bit B0 = load_be<u16bit>(in, 0);
u16bit B1 = load_be<u16bit>(in, 1);
u16bit B2 = load_be<u16bit>(in, 2);
u16bit B3 = load_be<u16bit>(in, 3);
for(u32bit j = 0; j != 8; j += 2)
{
const u16bit* K = EK + 8*j;
u16bit R = B1 ^ (rotate_left(B0, 1) & K[0]);
u16bit L = B0 ^ (rotate_left(R, 1) | K[1]);
L = FI(L ^ K[ 2], K[ 3]) ^ R;
R = FI(R ^ K[ 4], K[ 5]) ^ L;
L = FI(L ^ K[ 6], K[ 7]) ^ R;
R = B2 ^= R;
L = B3 ^= L;
R = FI(R ^ K[10], K[11]) ^ L;
L = FI(L ^ K[12], K[13]) ^ R;
R = FI(R ^ K[14], K[15]) ^ L;
R ^= (rotate_left(L, 1) & K[8]);
L ^= (rotate_left(R, 1) | K[9]);
B0 ^= L;
B1 ^= R;
}
store_be(out, B0, B1, B2, B3);
}
/*************************************************
* KASUMI Decryption *
*************************************************/
void KASUMI::dec(const byte in[], byte out[]) const
{
u16bit B0 = load_be<u16bit>(in, 0);
u16bit B1 = load_be<u16bit>(in, 1);
u16bit B2 = load_be<u16bit>(in, 2);
u16bit B3 = load_be<u16bit>(in, 3);
for(u32bit j = 0; j != 8; j += 2)
{
const u16bit* K = EK + 8*(6-j);
u16bit L = B2, R = B3;
L = FI(L ^ K[10], K[11]) ^ R;
R = FI(R ^ K[12], K[13]) ^ L;
L = FI(L ^ K[14], K[15]) ^ R;
L ^= (rotate_left(R, 1) & K[8]);
R ^= (rotate_left(L, 1) | K[9]);
R = B0 ^= R;
L = B1 ^= L;
L ^= (rotate_left(R, 1) & K[0]);
R ^= (rotate_left(L, 1) | K[1]);
R = FI(R ^ K[2], K[3]) ^ L;
L = FI(L ^ K[4], K[5]) ^ R;
R = FI(R ^ K[6], K[7]) ^ L;
B2 ^= L;
B3 ^= R;
}
store_be(out, B0, B1, B2, B3);
}
/*************************************************
* KASUMI Key Schedule *
*************************************************/
void KASUMI::key(const byte key[], u32bit)
{
static const u16bit RC[] = { 0x0123, 0x4567, 0x89AB, 0xCDEF,
0xFEDC, 0xBA98, 0x7654, 0x3210 };
SecureBuffer<u16bit, 16> K;
for(u32bit j = 0; j != 8; ++j)
{
K[j] = load_be<u16bit>(key, j);
K[j+8] = K[j] ^ RC[j];
}
for(u32bit j = 0; j != 8; ++j)
{
EK[8*j ] = rotate_left(K[(j+0) % 8 ], 2);
EK[8*j+1] = rotate_left(K[(j+2) % 8 + 8], 1);
EK[8*j+2] = rotate_left(K[(j+1) % 8 ], 5);
EK[8*j+3] = K[(j+4) % 8 + 8];
EK[8*j+4] = rotate_left(K[(j+5) % 8 ], 8);
EK[8*j+5] = K[(j+3) % 8 + 8];
EK[8*j+6] = rotate_left(K[(j+6) % 8 ], 13);
EK[8*j+7] = K[(j+7) % 8 + 8];
}
}
}
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