📄 cast256.cpp
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/* CAST-256 Block Cypher Implementation
Copyright (C) 1999, Daniel Roethlisberger
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
The author of this program may be contacted at admin@roe.ch.
*/
#include "cast256.h"
#include "cast256s.h"
// ========================================================================
// Support defines
// ------------------------------------------------------------------------
#define DWORD unsigned long
// Rotate Left operation
#define ROTL(x,n) (((x) << (n)) | ((x) >> (32 - (n))))
// Extract the nth BYTE from a DWORD
#define EXT_A(x) ((int)((x >> 24) & 0xFF))
#define EXT_B(x) ((int)((x >> 16) & 0xFF))
#define EXT_C(x) ((int)((x >> 8) & 0xFF))
#define EXT_D(x) ((int)((x) & 0xFF))
// Five least significant bits
#define FIVE_LSB(x) ((x) & (DWORD)0x0000001F)
// Fill in the rotation subkey from KAPPA
#define Kr_FILL(i,k) \
Kr[i].A = FIVE_LSB(k.A); \
Kr[i].B = FIVE_LSB(k.C); \
Kr[i].C = FIVE_LSB(k.E); \
Kr[i].D = FIVE_LSB(k.G)
// Fill in the mask subkey from KAPPA
#define Km_FILL(i,k) \
Km[i].A = k.H; \
Km[i].B = k.F; \
Km[i].C = k.D; \
Km[i].D = k.B
// ========================================================================
// The global rotation and mask round subkey generation tables
// ------------------------------------------------------------------------
KAPPA g_Tr[24];
KAPPA g_Tm[24];
// ========================================================================
// The F-Functions
// ------------------------------------------------------------------------
DWORD __inline f1(DWORD D, DWORD Kri, DWORD Kmi)
{
DWORD I = ROTL((Kmi + D), Kri);
return ((S1[EXT_A(I)] ^ S2[EXT_B(I)]) - S3[EXT_C(I)]) + S4[EXT_D(I)];
}
DWORD __inline f2(DWORD D, DWORD Kri, DWORD Kmi)
{
DWORD I = ROTL((Kmi ^ D), Kri);
return ((S1[EXT_A(I)] - S2[EXT_B(I)]) + S3[EXT_C(I)]) ^ S4[EXT_D(I)];
}
DWORD __inline f3(DWORD D, DWORD Kri, DWORD Kmi)
{
DWORD I = ROTL((Kmi - D), Kri);
return ((S1[EXT_A(I)] + S2[EXT_B(I)]) ^ S3[EXT_C(I)]) - S4[EXT_D(I)];
}
// ========================================================================
// The Quad-Round and Reverse Quad Round
// ------------------------------------------------------------------------
BETA __inline Q(int round, BETA data, BETA* Kr, BETA* Km)
{
data.C = data.C ^ f1(data.D, Kr[round].A, Km[round].A);
data.B = data.B ^ f2(data.C, Kr[round].B, Km[round].B);
data.A = data.A ^ f3(data.B, Kr[round].C, Km[round].C);
data.D = data.D ^ f1(data.A, Kr[round].D, Km[round].D);
return data;
}
BETA __inline QBAR(int round, BETA data, BETA* Kr, BETA* Km)
{
data.D = data.D ^ f1(data.A, Kr[round].D, Km[round].D);
data.A = data.A ^ f3(data.B, Kr[round].C, Km[round].C);
data.B = data.B ^ f2(data.C, Kr[round].B, Km[round].B);
data.C = data.C ^ f1(data.D, Kr[round].A, Km[round].A);
return data;
}
// ========================================================================
// The Forward Octave
// ------------------------------------------------------------------------
KAPPA __inline W(int round, KAPPA data, KAPPA* Tr, KAPPA* Tm)
{
data.G = data.G ^ f1(data.H, Tr[round].A, Tm[round].A);
data.F = data.F ^ f2(data.G, Tr[round].B, Tm[round].B);
data.E = data.E ^ f3(data.F, Tr[round].C, Tm[round].C);
data.D = data.D ^ f1(data.E, Tr[round].D, Tm[round].D);
data.C = data.C ^ f2(data.D, Tr[round].E, Tm[round].E);
data.B = data.B ^ f3(data.C, Tr[round].F, Tm[round].F);
data.A = data.A ^ f1(data.B, Tr[round].G, Tm[round].G);
data.H = data.H ^ f2(data.A, Tr[round].H, Tm[round].H);
return data;
}
// ========================================================================
// Encrypt a 128bit block
// ------------------------------------------------------------------------
void CAST256Encrypt(BETA *Kr, BETA *Km, BETA *pData)
{
for(int i = 0; i < 6; i++)
*pData = Q(i, *pData, Kr, Km);
for(i = 6; i < 12; i++)
*pData = QBAR(i, *pData, Kr, Km);
}
// ========================================================================
// Decrypt a 128bit block
// ------------------------------------------------------------------------
void CAST256Decrypt(BETA *Kr, BETA *Km, BETA *pData)
{
for(int i = 11; i >= 6; i--)
*pData = Q(i, *pData, Kr, Km);
for(i = 5; i >= 0; i--)
*pData = QBAR(i, *pData, Kr, Km);
}
// ========================================================================
// Initialize the mask and rotation round subkey sets from a given user key
// ------------------------------------------------------------------------
void CAST256KeyInit(BETA *Kr, BETA *Km, KAPPA userKey)
{
for(int i = 0; i < 12; i++)
{
userKey = W(2*i, userKey, g_Tr, g_Tm);
userKey = W(2*i+1, userKey, g_Tr, g_Tm);
Kr_FILL(i, userKey);
Km_FILL(i, userKey);
}
}
// ========================================================================
// Initialize the tables used for key initialization / expansion
// ------------------------------------------------------------------------
void CAST256TableInit(void)
{
DWORD Cm = 0x5A827999;
DWORD Mm = 0x6ED9EBA1;
DWORD Cr = 19;
DWORD Mr = 17;
for(int i = 0; i < 24; i++)
{
g_Tm[i].A = Cm;
Cm += Mm;
g_Tm[i].B = Cm;
Cm += Mm;
g_Tm[i].C = Cm;
Cm += Mm;
g_Tm[i].D = Cm;
Cm += Mm;
g_Tm[i].E = Cm;
Cm += Mm;
g_Tm[i].F = Cm;
Cm += Mm;
g_Tm[i].G = Cm;
Cm += Mm;
g_Tm[i].H = Cm;
Cm += Mm;
g_Tr[i].A = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].B = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].C = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].D = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].E = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].F = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].G = Cr;
Cr = FIVE_LSB(Cr + Mr);
g_Tr[i].H = Cr;
Cr = FIVE_LSB(Cr + Mr);
}
}
// ========================================================================
// CAST-256 Test Code
// ------------------------------------------------------------------------
/*
#include <stdio.h>
#include <string.h>
#include <conio.h>
void main(void)
{
printf("CAST-256 Block Cypher Implementation\nCopyright (C) 1999, Daniel Roethlisberger <admin@roe.ch>\n\nThis program is free software under the GNU license.\nLet me know if you use it.\n\n");
BETA Kr[CAST_ROUNDS];
BETA Km[CAST_ROUNDS];
// Simple encryption/decryption test
printf("Block Encryption/Decryption Test: ");
KAPPA uKey = {0x01234567, 0x89ABCDEF, 0x01234567, 0x89ABCDEF, 0x01234567, 0x89ABCDEF, 0x01234567, 0x89ABCDEF};
BETA Plain = {0xDEAFDEAF, 0xDEAFDEAF, 0xDEAFDEAF, 0xDEAFDEAF};
BETA Cypher = {0xDEAFDEAF, 0xDEAFDEAF, 0xDEAFDEAF, 0xDEAFDEAF};
// Initialize tables and keys
CAST256TableInit();
CAST256KeyInit(Kr, Km, uKey);
// Encrypt and decrypt Cypher
CAST256Encrypt(Kr, Km, &Cypher);
CAST256Decrypt(Kr, Km, &Cypher);
// Check result. Cypher must be equal to Plain
if(!memcmp(&Plain, &Cypher, 16))
printf("PASSED\n");
else
printf("FAILED\n");
// RFC2612's defined reference vector test
printf("RFC 2612 Reference Vector Test: ");
// Defined user key
uKey.A = 0x2342bb9e;
uKey.B = 0xfa38542c;
uKey.C = 0xbed0ac83;
uKey.D = 0x940ac298;
uKey.E = 0x8d7c47ce;
uKey.F = 0x26490846;
uKey.G = 0x1cc1b513;
uKey.H = 0x7ae6b604;
// Defined plaintext
Plain.A = 0x00000000;
Plain.B = 0x00000000;
Plain.C = 0x00000000;
Plain.D = 0x00000000;
// Defined corresponding cyphertext
Cypher.A = 0x4f6a2038;
Cypher.B = 0x286897b9;
Cypher.C = 0xc9870136;
Cypher.D = 0x553317fa;
// Initialize tables and keys
CAST256TableInit();
CAST256KeyInit(Kr, Km, uKey);
// Encrypt the test vector (=Plain)
CAST256Encrypt(Kr, Km, &Plain);
// Check whether Plain encrypted to the correct cyphertext (=Cypher)
if(!memcmp(&Plain, &Cypher, 16))
printf("PASSED\n");
else
printf("FAILED\n");
printf("\nPress any key to return...\n\n");
getch();
}
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