Comments are provided as needed to understand the program.
*/
// Include stdio.h for standard input/output.
// Used for giving output to the screen.
#include<stdio.h>
// The number of columns comprising a state in AES. This is a
constant in AES. Value=4
#define Nb 4
// The number of rounds in AES Cipher. It is simply initiated to
zero. The actual value is recieved in the program.
int Nr=0;
// The number of 32 bit words in the key. It is simply initiated
to zero. The actual value is recieved in the program.
int Nk=0;
// in - it is the array that holds the plain text to be
encrypted.
// out - it is the array that holds the key for encryption.
// state - the array that holds the intermediate results during
encryption.
unsigned char in[16], out[16], state[4][4];
// The array that stores the round keys.
unsigned char RoundKey[240];
// The Key input to the AES Program
unsigned char Key[32];
int getSBoxValue(int num)
{
//giving input in program itself. if input to be read from file input.txt , key.txt then comment the below part and in main() function reading file file code to be executed.
int sbox[256] = {
//0 1 2 3 4 5 6 7 8 9 A B C D E F
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30,
0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, //0
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad,
0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, //1
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34,
0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, //2
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07,
0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, //3
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52,
0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, //4
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a,
0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, //5
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45,
0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, //6
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc,
0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, //7
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4,
0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, //8
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46,
0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, //9
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2,
0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, //A
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c,
0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, //B
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8,
0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, //C
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61,
0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, //D
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b,
0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, //E
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41,
0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }; //F
return sbox[num];
}
// The round constant word array, Rcon[i], contains the values
given by
// x to th e power (i-1) being powers of x (x is denoted as {02})
in the field GF(28)
// Note that i starts at 1, not 0).
int Rcon[255] = {
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 };
// This function produces Nb(Nr+1) round keys. The round keys
are used in each round to encrypt the states.
void KeyExpansion()
{
int i,j;
unsigned char temp[4],k;
// The first round key is the key itself.
for(i=0;i<Nk;i++)
{
RoundKey[i*4]=Key[i*4];
RoundKey[i*4+1]=Key[i*4+1];
RoundKey[i*4+2]=Key[i*4+2];
RoundKey[i*4+3]=Key[i*4+3];
}
// All other round keys are found from the previous
round keys.
while (i < (Nb * (Nr+1)))
{
for(j=0;j<4;j++)
{
temp[j]=RoundKey[(i-1) * 4 + j];
}
if (i % Nk == 0)
{
// This
function rotates the 4 bytes in a word to the left once.
//
[a0,a1,a2,a3] becomes [a1,a2,a3,a0]
//
Function RotWord()
{
k = temp[0];
temp[0] = temp[1];
temp[1] = temp[2];
temp[2] = temp[3];
temp[3] = k;
}
//
SubWord() is a function that takes a four-byte input word and
// applies
the S-box to each of the four bytes to produce an output word.
//
Function Subword()
{
temp[0]=getSBoxValue(temp[0]);
temp[1]=getSBoxValue(temp[1]);
temp[2]=getSBoxValue(temp[2]);
temp[3]=getSBoxValue(temp[3]);
}
temp[0] =
temp[0] ^ Rcon[i/Nk];
}
else if (Nk > 6 &&
i % Nk == 4)
{
//
Function Subword()
{
temp[0]=getSBoxValue(temp[0]);
temp[1]=getSBoxValue(temp[1]);
temp[2]=getSBoxValue(temp[2]);
temp[3]=getSBoxValue(temp[3]);
}
}
RoundKey[i*4+0] =
RoundKey[(i-Nk)*4+0] ^ temp[0];
RoundKey[i*4+1] =
RoundKey[(i-Nk)*4+1] ^ temp[1];
RoundKey[i*4+2] =
RoundKey[(i-Nk)*4+2] ^ temp[2];
RoundKey[i*4+3] =
RoundKey[(i-Nk)*4+3] ^ temp[3];
i++;
}
}
// This function adds the round key to state.
// The round key is added to the state by an XOR function.
void AddRoundKey(int round)
{
int i,j;
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[j][i] ^=
RoundKey[round * Nb * 4 + i * Nb + j];
}
}
}
// The SubBytes Function Substitutes the values in the
// state matrix with values in an S-box.
void SubBytes()
{
int i,j;
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[i][j] =
getSBoxValue(state[i][j]);
}
}
}
// The ShiftRows() function shifts the rows in the state to the
left.
// Each row is shifted with different offset.
// Offset = Row number. So the first row is not shifted.
void ShiftRows()
{
unsigned char temp;
// Rotate first row 1 columns to
left
temp=state[1][0];
state[1][0]=state[1][1];
state[1][1]=state[1][2];
state[1][2]=state[1][3];
state[1][3]=temp;
// Rotate second row 2 columns to
left
temp=state[2][0];
state[2][0]=state[2][2];
state[2][2]=temp;
temp=state[2][1];
state[2][1]=state[2][3];
state[2][3]=temp;
// Rotate third row 3 columns to left
temp=state[3][0];
state[3][0]=state[3][3];
state[3][3]=state[3][2];
state[3][2]=state[3][1];
state[3][1]=temp;
}
// xtime is a macro that finds the product of {02} and the
argument to xtime modulo {1b}
#define xtime(x) ((x<<1) ^ (((x>>7) & 1) *
0x1b))
// MixColumns function mixes the columns of the state
matrix
void MixColumns()
{
int i;
unsigned char Tmp,Tm,t;
for(i=0;i<4;i++)
{
t=state[0][i];
Tmp = state[0][i] ^ state[1][i] ^
state[2][i] ^ state[3][i] ;
Tm = state[0][i] ^ state[1][i] ; Tm
= xtime(Tm); state[0][i] ^= Tm ^ Tmp ;
Tm = state[1][i] ^ state[2][i] ; Tm
= xtime(Tm); state[1][i] ^= Tm ^ Tmp ;
Tm = state[2][i] ^ state[3][i] ; Tm
= xtime(Tm); state[2][i] ^= Tm ^ Tmp ;
Tm = state[3][i] ^ t ; Tm =
xtime(Tm); state[3][i] ^= Tm ^ Tmp ;
}
}
// Cipher is the main function that encrypts the
PlainText.
void Cipher()
{
int i,j,round=0;
//Copy the input PlainText to state array.
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[j][i] =
in[i*4 + j];
}
}
// Add the First round key to the state before
starting the rounds.
AddRoundKey(0);
// There will be Nr rounds.
// The first Nr-1 rounds are identical.
// These Nr-1 rounds are executed in the loop
below.
for(round=1;round<Nr;round++)
{
SubBytes();
ShiftRows();
MixColumns();
AddRoundKey(round);
}
// The last round is given below.
// The MixColumns function is not here in the last
round.
SubBytes();
ShiftRows();
AddRoundKey(Nr);
// The encryption process is over.
// Copy the state array to output array.
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
out[i*4+j]=state[j][i];
}
}
}
void main()
{
int i;
// Recieve the length of key here.
while(Nr!=128 && Nr!=192 &&
Nr!=256)
{
printf("Enter the length of
Key(128, 192 or 256 only): ");
scanf("%d",&Nr);
}
// Calculate Nk and Nr from the recieved value.
Nk = Nr / 32;
Nr = Nk + 6;
// The array temp stores the key.
// The array temp2 stores the plaintext.
unsigned char temp[16] = {0x00 ,0x01 ,0x02 ,0x03 ,0x04
,0x05 ,0x06 ,0x07 ,0x08 ,0x09 ,0x0a ,0x0b ,0x0c ,0x0d ,0x0e
,0x0f};
unsigned char temp2[16]= {0x00 ,0x11 ,0x22 ,0x33 ,0x44
,0x55 ,0x66 ,0x77 ,0x88 ,0x99 ,0xaa ,0xbb ,0xcc ,0xdd ,0xee
,0xff};
// Copy the Key and PlainText
for(i=0;i<Nk*4;i++)
{
Key[i]=temp[i];
in[i]=temp2[i];
}
// *********************************************************
//Clear the input buffer
flushall();
//Recieve the key from the user
printf("Enter the Key in hexadecimal: ");
for(i=0;i<Nk*4;i++)
{
scanf("%x",&Key[i]);
}
printf("Enter the PlainText in hexadecimal:
");
for(i=0;i<Nb*4;i++)
{
scanf("%x",&in[i]);
}
//to read the plain text and key from text
files.(plain,txt,key.txt)
FILE * pt_file; string str; pt_file = fopen( "plain.txt" , "r"); if (pt_file) { while (fscanf(pt_file, "%s", str)!=EOF) { for(i=0;i<Nb*4;i++) { in[i]=str; } } fclose(pt_file);
FILE * key_file; key_file = fopen( "key.txt" , "r"); if (key_file) { while (fscanf(key_file, "%s", str)!=EOF) { for(i=0;i<Nk*4;i++) { key[i]=str; } } fclose(key_file);
// The KeyExpansion routine must be called before
encryption.
KeyExpansion();
// The next function call encrypts the PlainText
with the Key using AES algorithm.
Cipher();
// Output the encrypted text.
printf("\nText after encryption:\n");
for(i=0;i<Nk*4;i++)
{
printf("%02x ",out[i]);
}
printf("\n\n");
}
AES Decryption,
// Include stdio.h for standard input/output.
// Used for giving output to the screen.
#include<stdio.h>
// The number of columns comprising a state in AES. This is a
constant in AES. Value=4
#define Nb 4
// The number of rounds in AES Cipher. It is simply initiated to
zero. The actual value is recieved in the program.
int Nr=0;
// The number of 32 bit words in the key. It is simply initiated
to zero. The actual value is recieved in the program.
int Nk=0;
// in - it is the array that holds the CipherText to be
decrypted.
// out - it is the array that holds the output of the for
decryption.
// state - the array that holds the intermediate results during
decryption.
unsigned char in[16], out[16], state[4][4];
// The array that stores the round keys.
unsigned char RoundKey[240];
// The Key input to the AES Program
unsigned char Key[32];
int getSBoxInvert(int num)
{
int rsbox[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 };
return rsbox[num];
}
int getSBoxValue(int num)
{
int sbox[256] = {
//0 1 2 3 4 5 6 7 8 9 A B C D E F
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 };
return sbox[num];
}
// The round constant word array, Rcon[i], contains the values
given by
// x to th e power (i-1) being powers of x (x is denoted as {02})
in the field GF(2^8)
// Note that i starts at 1, not 0).
int Rcon[255] = {
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 };
// This function produces Nb(Nr+1) round keys. The round keys
are used in each round to decrypt the states.
void KeyExpansion()
{
int i,j;
unsigned char temp[4],k;
// The first round key is the key itself.
for(i=0;i<Nk;i++)
{
RoundKey[i*4]=Key[i*4];
RoundKey[i*4+1]=Key[i*4+1];
RoundKey[i*4+2]=Key[i*4+2];
RoundKey[i*4+3]=Key[i*4+3];
}
// All other round keys are found from the previous
round keys.
while (i < (Nb * (Nr+1)))
{
for(j=0;j<4;j++)
{
temp[j]=RoundKey[(i-1) * 4 + j];
}
if (i % Nk == 0)
{
// This function
rotates the 4 bytes in a word to the left once.
// [a0,a1,a2,a3]
becomes [a1,a2,a3,a0]
// Function
RotWord()
{
k = temp[0];
temp[0] = temp[1];
temp[1] = temp[2];
temp[2] = temp[3];
temp[3] = k;
}
// SubWord()
is a function that takes a four-byte input word and
// applies the
S-box to each of the four bytes to produce an output word.
// Function
Subword()
{
temp[0]=getSBoxValue(temp[0]);
temp[1]=getSBoxValue(temp[1]);
temp[2]=getSBoxValue(temp[2]);
temp[3]=getSBoxValue(temp[3]);
}
temp[0] =
temp[0] ^ Rcon[i/Nk];
}
else if (Nk > 6 && i %
Nk == 4)
{
// Function
Subword()
{
temp[0]=getSBoxValue(temp[0]);
temp[1]=getSBoxValue(temp[1]);
temp[2]=getSBoxValue(temp[2]);
temp[3]=getSBoxValue(temp[3]);
}
}
RoundKey[i*4+0] =
RoundKey[(i-Nk)*4+0] ^ temp[0];
RoundKey[i*4+1] =
RoundKey[(i-Nk)*4+1] ^ temp[1];
RoundKey[i*4+2] =
RoundKey[(i-Nk)*4+2] ^ temp[2];
RoundKey[i*4+3] =
RoundKey[(i-Nk)*4+3] ^ temp[3];
i++;
}
}
// This function adds the round key to state.
// The round key is added to the state by an XOR function.
void AddRoundKey(int round)
{
int i,j;
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[j][i] ^=
RoundKey[round * Nb * 4 + i * Nb + j];
}
}
}
// The SubBytes Function Substitutes the values in the
// state matrix with values in an S-box.
void InvSubBytes()
{
int i,j;
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[i][j] =
getSBoxInvert(state[i][j]);
}
}
}
// The ShiftRows() function shifts the rows in the state to the
left.
// Each row is shifted with different offset.
// Offset = Row number. So the first row is not shifted.
void InvShiftRows()
{
unsigned char temp;
// Rotate first row 1 columns to
right
temp=state[1][3];
state[1][3]=state[1][2];
state[1][2]=state[1][1];
state[1][1]=state[1][0];
state[1][0]=temp;
// Rotate second row 2 columns to
right
temp=state[2][0];
state[2][0]=state[2][2];
state[2][2]=temp;
temp=state[2][1];
state[2][1]=state[2][3];
state[2][3]=temp;
// Rotate third row 3 columns to right
temp=state[3][0];
state[3][0]=state[3][1];
state[3][1]=state[3][2];
state[3][2]=state[3][3];
state[3][3]=temp;
}
// xtime is a macro that finds the product of {02} and the
argument to xtime modulo {1b}
#define xtime(x) ((x<<1) ^ (((x>>7) & 1) *
0x1b))
// Multiplty is a macro used to multiply numbers in the field
GF(2^8)
#define Multiply(x,y) (((y & 1) * x) ^ ((y>>1 & 1) *
xtime(x)) ^ ((y>>2 & 1) * xtime(xtime(x))) ^ ((y>>3
& 1) * xtime(xtime(xtime(x)))) ^ ((y>>4 & 1) *
xtime(xtime(xtime(xtime(x))))))
// MixColumns function mixes the columns of the state
matrix.
// The method used to multiply may be difficult to understand for
the inexperienced.
// Please use the references to gain more information.
void InvMixColumns()
{
int i;
unsigned char a,b,c,d;
for(i=0;i<4;i++)
{
a = state[0][i];
b = state[1][i];
c = state[2][i];
d = state[3][i];
state[0][i] = Multiply(a, 0x0e) ^
Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
state[1][i] = Multiply(a, 0x09) ^
Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
state[2][i] = Multiply(a, 0x0d) ^
Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
state[3][i] = Multiply(a, 0x0b) ^
Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
}
}
// InvCipher is the main function that decrypts the
CipherText.
void InvCipher()
{
int i,j,round=0;
//Copy the input CipherText to state array.
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
state[j][i] =
in[i*4 + j];
}
}
// Add the First round key to the state before
starting the rounds.
AddRoundKey(Nr);
// There will be Nr rounds.
// The first Nr-1 rounds are identical.
// These Nr-1 rounds are executed in the loop
below.
for(round=Nr-1;round>0;round--)
{
InvShiftRows();
InvSubBytes();
AddRoundKey(round);
InvMixColumns();
}
// The last round is given below.
// The MixColumns function is not here in the last
round.
InvShiftRows();
InvSubBytes();
AddRoundKey(0);
// The decryption process is over.
// Copy the state array to output array.
for(i=0;i<4;i++)
{
for(j=0;j<4;j++)
{
out[i*4+j]=state[j][i];
}
}
}
void main()
{
int i;
// Recieve the length of key here.
while(Nr!=128 && Nr!=192 &&
Nr!=256)
{
printf("Enter the length of
Key(128, 192 or 256 only): ");
scanf("%d",&Nr);
}
// Calculate Nk and Nr from the recieved value.
Nk = Nr / 32;
Nr = Nk + 6;
// Part 1 is for demonstrative purpose. The key and plaintext
are given in the program itself.
// Part 1:
********************************************************
// The array temp stores the key.
// The array temp2 stores the plaintext.
unsigned char temp[32] = {0x00 ,0x01 ,0x02 ,0x03 ,0x04
,0x05 ,0x06 ,0x07 ,0x08 ,0x09 ,0x0a ,0x0b ,0x0c ,0x0d ,0x0e
,0x0f};
unsigned char temp2[16]= {0x69 ,0xc4 ,0xe0 ,0xd8 ,0x6a
,0x7b ,0x04 ,0x30 ,0xd8 ,0xcd ,0xb7 ,0x80 ,0x70 ,0xb4 ,0xc5
,0x5a};
// Copy the Key and CipherText
for(i=0;i<Nk*4;i++)
{
Key[i]=temp[i];
in[i]=temp2[i];
}
// *********************************************************
// Uncomment Part 2 if you need to read Key and CipherText from the
keyboard.
// Part 2:
********************************************************
/*
//Clear the input buffer
flushall();
//Recieve the Key from the user
printf("Enter the Key in hexadecimal: ");
for(i=0;i<Nk*4;i++)
{
scanf("%x",&Key[i]);
}
printf("Enter the CipherText in hexadecimal:
");
for(i=0;i<Nb*4;i++)
{
scanf("%x",&in[i]);
}
*/
//
********************************************************
//The Key-Expansion routine must be called before the
decryption routine.
KeyExpansion();
// The next function call decrypts the CipherText
with the Key using AES algorithm.
InvCipher();
// Output the decrypted text.
printf("\nText after decryption:\n");
for(i=0;i<Nb*4;i++)
{
printf("%02x ",out[i]);
}
printf("\n\n");
}
Final Project-1 A Modified XTS-AES Encryption and Decryption Input File: input. and key txt Time Limit:...
Implement in Go language AES encryption mode CBC with providing the packages name for Go language. You can implement AES-ECB Mode (the basic AES) from crypto/aes package and crypto/cipher.Block. You can also get the SHA-256 hash function from crypto/sha256. You can get the secure random numbers generator from crypto/rand package. However, the you will implement both CBC mode and HMAC from scratch. You are NOT allowed to use any libraries or packages to implement these two things for you. You...
1) Echo the input: First, you should make sure you can write a program and have it compile and run, take input and give output. So to start you should just echo the input. This means you should prompt the user for the plaintext, read it in and then print it back out, with a message such as "this is the plaintext you entered:". [4 points, for writing a working program, echoing the input and submitting the program on the...