Code:
#include <stdio.h>
#define A 16807
#define M 2147483647
#define Q 127773 /* = M/A */
#define R 2836 /* = M%A */
void KeyExpansion(unsigned char [16]);
void SubWord(unsigned char *);
void RotWord(unsigned char *);
void AddRoundKey(unsigned char (*)[4], int);
void InvCipher(unsigned char *, unsigned char *);
void InvShiftRows(unsigned char (*)[4]);
void InvSubBytes(unsigned char (*)[4]);
void InvMixColumns(unsigned char (*)[4]);
void PrintState(unsigned char [4][4]);
void PrintPlaintext(unsigned char *);
int times(int, int);
int CheckBlock(unsigned char *);
unsigned long irandom(void);
unsigned char Rcon[] = {
0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40,
0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a,
0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,
0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25,
0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08,
0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6,
0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,
0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61,
0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01,
0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,
0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e,
0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4,
0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,
0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8,
0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d,
0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91,
0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,
0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d,
0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c,
0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,
0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa,
0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,
0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66,
0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb};
/* GF(256) logarithm */
int L[256] = {
-1, 0, 0x19, 0x01, 0x32, 0x02, 0x1a, 0xc6,
0x4b, 0xc7, 0x1b, 0x68, 0x33, 0xee, 0xdf, 0x03,
0x64, 0x04, 0xe0, 0x0e, 0x34, 0x8d, 0x81, 0xef,
0x4c, 0x71, 0x08, 0xc8, 0xf8, 0x69, 0x1c, 0xc1,
0x7d, 0xc2, 0x1d, 0xb5, 0xf9, 0xb9, 0x27, 0x6a,
0x4d, 0xe4, 0xa6, 0x72, 0x9a, 0xc9, 0x09, 0x78,
0x65, 0x2f, 0x8a, 0x05, 0x21, 0x0f, 0xe1, 0x24,
0x12, 0xf0, 0x82, 0x45, 0x35, 0x93, 0xda, 0x8e,
0x96, 0x8f, 0xdb, 0xbd, 0x36, 0xd0, 0xce, 0x94,
0x13, 0x5c, 0xd2, 0xf1, 0x40, 0x46, 0x83, 0x38,
0x66, 0xdd, 0xfd, 0x30, 0xbf, 0x06, 0x8b, 0x62,
0xb3, 0x25, 0xe2, 0x98, 0x22, 0x88, 0x91, 0x10,
0x7e, 0x6e, 0x48, 0xc3, 0xa3, 0xb6, 0x1e, 0x42,
0x3a, 0x6b, 0x28, 0x54, 0xfa, 0x85, 0x3d, 0xba,
0x2b, 0x79, 0x0a, 0x15, 0x9b, 0x9f, 0x5e, 0xca,
0x4e, 0xd4, 0xac, 0xe5, 0xf3, 0x73, 0xa7, 0x57,
0xaf, 0x58, 0xa8, 0x50, 0xf4, 0xea, 0xd6, 0x74,
0x4f, 0xae, 0xe9, 0xd5, 0xe7, 0xe6, 0xad, 0xe8,
0x2c, 0xd7, 0x75, 0x7a, 0xeb, 0x16, 0x0b, 0xf5,
0x59, 0xcb, 0x5f, 0xb0, 0x9c, 0xa9, 0x51, 0xa0,
0x7f, 0x0c, 0xf6, 0x6f, 0x17, 0xc4, 0x49, 0xec,
0xd8, 0x43, 0x1f, 0x2d, 0xa4, 0x76, 0x7b, 0xb7,
0xcc, 0xbb, 0x3e, 0x5a, 0xfb, 0x60, 0xb1, 0x86,
0x3b, 0x52, 0xa1, 0x6c, 0xaa, 0x55, 0x29, 0x9d,
0x97, 0xb2, 0x87, 0x90, 0x61, 0xbe, 0xdc, 0xfc,
0xbc, 0x95, 0xcf, 0xcd, 0x37, 0x3f, 0x5b, 0xd1,
0x53, 0x39, 0x84, 0x3c, 0x41, 0xa2, 0x6d, 0x47,
0x14, 0x2a, 0x9e, 0x5d, 0x56, 0xf2, 0xd3, 0xab,
0x44, 0x11, 0x92, 0xd9, 0x23, 0x20, 0x2e, 0x89,
0xb4, 0x7c, 0xb8, 0x26, 0x77, 0x99, 0xe3, 0xa5,
0x67, 0x4a, 0xed, 0xde, 0xc5, 0x31, 0xfe, 0x18,
0x0d, 0x63, 0x8c, 0x80, 0xc0, 0xf7, 0x70, 0x07};
/* GF(256) antilogarithm */
int F[256] = {
0x01, 0x03, 0x05, 0x0f, 0x11, 0x33, 0x55, 0xff,
0x1a, 0x2e, 0x72, 0x96, 0xa1, 0xf8, 0x13, 0x35,
0x5f, 0xe1, 0x38, 0x48, 0xd8, 0x73, 0x95, 0xa4,
0xf7, 0x02, 0x06, 0x0a, 0x1e, 0x22, 0x66, 0xaa,
0xe5, 0x34, 0x5c, 0xe4, 0x37, 0x59, 0xeb, 0x26,
0x6a, 0xbe, 0xd9, 0x70, 0x90, 0xab, 0xe6, 0x31,
0x53, 0xf5, 0x04, 0x0c, 0x14, 0x3c, 0x44, 0xcc,
0x4f, 0xd1, 0x68, 0xb8, 0xd3, 0x6e, 0xb2, 0xcd,
0x4c, 0xd4, 0x67, 0xa9, 0xe0, 0x3b, 0x4d, 0xd7,
0x62, 0xa6, 0xf1, 0x08, 0x18, 0x28, 0x78, 0x88,
0x83, 0x9e, 0xb9, 0xd0, 0x6b, 0xbd, 0xdc, 0x7f,
0x81, 0x98, 0xb3, 0xce, 0x49, 0xdb, 0x76, 0x9a,
0xb5, 0xc4, 0x57, 0xf9, 0x10, 0x30, 0x50, 0xf0,
0x0b, 0x1d, 0x27, 0x69, 0xbb, 0xd6, 0x61, 0xa3,
0xfe, 0x19, 0x2b, 0x7d, 0x87, 0x92, 0xad, 0xec,
0x2f, 0x71, 0x93, 0xae, 0xe9, 0x20, 0x60, 0xa0,
0xfb, 0x16, 0x3a, 0x4e, 0xd2, 0x6d, 0xb7, 0xc2,
0x5d, 0xe7, 0x32, 0x56, 0xfa, 0x15, 0x3f, 0x41,
0xc3, 0x5e, 0xe2, 0x3d, 0x47, 0xc9, 0x40, 0xc0,
0x5b, 0xed, 0x2c, 0x74, 0x9c, 0xbf, 0xda, 0x75,
0x9f, 0xba, 0xd5, 0x64, 0xac, 0xef, 0x2a, 0x7e,
0x82, 0x9d, 0xbc, 0xdf, 0x7a, 0x8e, 0x89, 0x80,
0x9b, 0xb6, 0xc1, 0x58, 0xe8, 0x23, 0x65, 0xaf,
0xea, 0x25, 0x6f, 0xb1, 0xc8, 0x43, 0xc5, 0x54,
0xfc, 0x1f, 0x21, 0x63, 0xa5, 0xf4, 0x07, 0x09,
0x1b, 0x2d, 0x77, 0x99, 0xb0, 0xcb, 0x46, 0xca,
0x45, 0xcf, 0x4a, 0xde, 0x79, 0x8b, 0x86, 0x91,
0xa8, 0xe3, 0x3e, 0x42, 0xc6, 0x51, 0xf3, 0x0e,
0x12, 0x36, 0x5a, 0xee, 0x29, 0x7b, 0x8d, 0x8c,
0x8f, 0x8a, 0x85, 0x94, 0xa7, 0xf2, 0x0d, 0x17,
0x39, 0x4b, 0xdd, 0x7c, 0x84, 0x97, 0xa2, 0xfd,
0x1c, 0x24, 0x6c, 0xb4, 0xc7, 0x52, 0xf6, 0x01};
/* S-Box */
int SB[256] = {
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};
/* S-Box Inverse */
int SBI[256] = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38,
0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d,
0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2,
0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16,
0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a,
0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02,
0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea,
0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85,
0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89,
0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20,
0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31,
0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d,
0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0,
0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26,
0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d};
int Nr = 10; int Nb = 4; int Nk = 4;
unsigned int seed;
unsigned char w[44][4];
unsigned char characters[72] = {0x20, 0x21, 0x24, 0x25, 0x2C, 0x2d, 0x2e, 0x30, 0x31, 0x32,
0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3b, 0x3F,
0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a,
0x4b, 0x4c, 0x4d, 0x4e, 0X4f, 0x50, 0x51, 0x52, 0x53, 0x54,
0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x61, 0x62, 0x63, 0x64,
0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e,
0X6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
0x79, 0x7a};
void main() {
int i, j, round = 1;
unsigned char key[16], output[16], input[16];
unsigned char ciphertext[] = {0x64,0x5e,0xae,0x0d,0x03,0xbf,0x30,0xa1,0x97,0x39,0xa0,0xf5,0xcb,0x66,0x35,0xc9,
0xd5,0x02,0x70,0xd2,0xf8,0xb9,0xa4,0xdb,0x6e,0xf2,0x85,0x3e,0x38,0xdb,0xe5,0x55};
while(round > 0) {
seed = round;
if(round%1000000 == 0)
printf("checking at round %d\n", round);
/*generating key using seed*/
for(i=0;i<16;i++)
key[i] = irandom()>>23;
/*generate key schedule*/
KeyExpansion(key);
/*loop through each set of 16 bytes in the cipher text*/
for(i=0;i<2;i++) {
for(j=0;j<16;j++)
input[j] = ciphertext[i*16+j];
/*decipher the text and put in output*/
InvCipher(input, output);
if(i==0) { /*check first block*/
if(CheckBlock(output) == 1) { /*if there is an invalid character*/
i++; /*increment block so that program loops back to the begining to generate a new key*/
} else {
printf("Plaintext found at seed %d\n", round); /*print the first block of plaintext*/
PrintPlaintext(output);
}
}else {
PrintPlaintext(output); /*if the outer for loops to the second block,*/
printf("\n"); /*the first block contains valid characters, now print the second block*/
}
}
round++; /*increment round to set a new seed to generate a new key*/
}
}
/*CheckBlock checks each byte in a plaintext
to see if it contains any invalid characters.
The function returns 0 for a block that consists
of only valid characters, else 1*/
int CheckBlock(unsigned char *out) {
int j, i = 0;
int valid = 0;
/*while loop to check each character of the plaintext*/
while(valid == 0 && i<16) { /*while a non-character has not been found, valid will = 0*/
valid = 1; /*set valid = 1 at start of check*/
j=0;
while(valid == 1 && j<72) { /*loop through the array that contains a list of valid characters*/
if(out[i] == characters[j]) {
valid = 0; /*if the character is found in the character array, set valid to 0*/
}
j++;
}
i++; /*increment i to check the next character in the block*/
}
return valid; /*return the value 0 if entire block consists of valid characters, else return 1*/
}
/*KeyExpansion generates a series of */
/*round keys from the input key */
void KeyExpansion(unsigned char k1[16]){
unsigned char temp[4];
int i, j;
/*putting the key into w*/
for(i=0;i<Nk;i++) {
for(j=0;j<4;j++) {
w[i][j] = k1[4*i+j];
}
}
/*set i to nk to begin on 4th row 5th row of w*/
i = Nk;
while(i<(Nb*(Nr+1))) {
/*get the hex values for the row prior to current row*/
for(j=0;j<4;j++) {
temp[j] = w[i-1][j];
}
if((i % Nk) == 0) {
RotWord(temp);
SubWord(temp);
temp[0] = temp[0] ^ Rcon[i/Nk];
}
else if (Nk > 6 && (i % Nk) == 4) {
SubWord(temp);
}
for(j=0;j<4;j++) {
w[i][j] = temp[j]^w[i-Nk][j];
}
i++;
}
}
/*SubWord takes a four-byte input word */
/*SubWord takes a four-byte input word */
/*and applies an S-box to each of the four */
/*bytes to produce and output word */
void SubWord(unsigned char * t1) {
int i;
for(i=0;i<4;i++) {
t1[i] = SB[t1[i]];
}
}
/*RotWord takes a four-byte word */
/*and performs a cyclic permutation */
void RotWord(unsigned char * t1) {
unsigned char a1 = t1[0];
t1[0] = t1[1];
t1[1] = t1[2];
t1[2] = t1[3];
t1[3] = a1;
}
/*AddRoundKey adds a round key to the state */
/*using an XOR operation */
void AddRoundKey(unsigned char (*s)[4], int round) {
int i,j;
for(i=0;i<4;i++) {
for(j=0;j<4;j++) {
s[j][i] = s[j][i] ^ w[round*Nb+i][j];
}
}
}
/*InvCipher is the inverse of AES(Cipher) */
/*takes in a ciphertext and a 16 bytes key and */
/*deciphers the text into plaintext */
void InvCipher(unsigned char * in, unsigned char * out) {
unsigned char state[4][4];
int i, j;
/*Copy input into the state matrix*/
for(i=0;i<4;i++) {
for(j=0;j<4;j++) {
state[j][i] = in[4*i+j];
}
}
/*generate a key schedule*/
AddRoundKey(state, Nr);
/*loop through 10 rounds to decipher ciphertext*/
for(i=(Nr-1);i>0;i--) {
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, i);
InvMixColumns(state);
}
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, 0);
/*place plaintext into out array*/
for(i=0;i<4;i++) {
for(j=0;j<4;j++) {
out[i*4+j] = state[j][i];
}
}
}
/*InvShiftRows is the inverse of ShiftRows */
/*The last three rows of the state matrix */
/*are shifted to the right over incrementing */
/*offsets */
void InvShiftRows(unsigned char (*s)[4]) {
unsigned char temp;
/*shifts all bytes by one places to the right*/
temp = s[1][3];
s[1][3] = s[1][2];
s[1][2] = s[1][1];
s[1][1] = s[1][0];
s[1][0] = temp;
/*shifts all bytes by two places to the right*/
temp = s[2][3];
s[2][3] = s[2][1];
s[2][1] = temp;
temp = s[2][2];
s[2][2] = s[2][0];
s[2][0] = temp;
/*shift all bytes by three places to the right*/
temp = s[3][3];
s[3][3] = s[3][0];
s[3][0] = s[3][1];
s[3][1] = s[3][2];
s[3][2] = temp;
}
/*InvSubByes is the inverse of SubBytes */
/*Each byte of the state is substituted using */
/*the values obtained from the inverse S-box */
void InvSubBytes(unsigned char (*s)[4]) {
int i,j;
for(i=0;i<4;i++) {
for(j=0;j<4;j++) {
s[i][j] = SBI[s[i][j]];
}
}
}
/*InvMixColumns is the inverse of MixColumns*/
void InvMixColumns(unsigned char (*s)[4]) {
int i;
unsigned char temp[4][4];
/*perform calculations in temp matrix using values from state matrix that was passed into function*/
for(i=0;i<4;i++) {
temp[0][i] = times(0x0e, s[0][i])^times(0x0b, s[1][i])^times(0x0d, s[2][i])^times(0x09, s[3][i]);
temp[1][i] = times(0x09, s[0][i])^times(0x0e, s[1][i])^times(0x0b, s[2][i])^times(0x0d, s[3][i]);
temp[2][i] = times(0x0d, s[0][i])^times(0x09, s[1][i])^times(0x0e, s[2][i])^times(0x0b, s[3][i]);
temp[3][i] = times(0x0b, s[0][i])^times(0x0d, s[1][i])^times(0x09, s[2][i])^times(0x0e, s[3][i]);
}
/*places results calculated in temp matrix into state matrix that was passed into fuction*/
for(i=0;i<4;i++) {
s[0][i] = temp[0][i];
s[1][i] = temp[1][i];
s[2][i] = temp[2][i];
s[3][i] = temp[3][i];
}
}
int times(int x, int y) {
if(x==0 || y==0) return 0;
return F[(L[x]+L[y])%255];
}
/* In the array s[i][j], i is the row number and j is */
/* the column number. I had this mixed up originally. */
void PrintState(unsigned char s[4][4])
{
int i, j;
for(i = 0; i<4; i++) {
for(j = 0; j<4; j++) {
printf("%02x ", s[i][j]);
}
printf("\n");
}
}
/*Prints out a plaintext in ascii*/
void PrintPlaintext(unsigned char *out) {
int i;
/*loop through the array*/
for(i=0;i<16;i++){
/*prints out the value in each index*/
printf("%c", out[i]);
}
}
/**********************************************************************/
/* */
/* irandom(void) returns a long between 1 and M-1=2^31-2. Every */
/* integer between 0 and M-1 will occur before the sequence starts */
/* to repeat. */
/* */
/* Method is based on Park and Miller, "Random number generators: */
/* good ones are hard to find", Comm. ACM Vol. 31 pp. 1192-1201, */
/* October, 1989. If you want a different initial random number, */
/* put some randomly chosen value such as current time into the */
/* global variable "seed". (WP--12/89) */
/* */
/**********************************************************************/
unsigned long irandom(void)
{
long lo, hi;
hi = R*(seed/Q);
lo = A*(seed%Q);
if(lo>hi) seed = lo-hi;
else seed = (M-hi) + lo;
return(seed);
}
Regards,