/*
* This is an implementation of the AES algorithm,
* specifically ECB, CTR and CBC mode.
* Block size can be chosen in aes.h - available choices are AES128,
* AES192, AES256.
*
* The implementation is verified against the test vectors in:
* National Institute of Standards and Technology
* Special Publication 800-38A 2001 ED
ECB-AES128
----------
plain-text:
6bc1bee22e409f96e93d7e117393172a
ae2d8a571e03ac9c9eb76fac45af8e51
30c81c46a35ce411e5fbc1191a0a52ef
f69f2445df4f9b17ad2b417be66c3710
key:
2b7e151628aed2a6abf7158809cf4f3c
resulting cipher
3ad77bb40d7a3660a89ecaf32466ef97
f5d3d58503b9699de785895a96fdbaaf
43b1cd7f598ece23881b00e3ed030688
7b0c785e27e8ad3f8223207104725dd4
NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
You should pad the end of the string with zeros
if this is not the case. For AES192/256 the key size is
proportionally larger.
*/
module tiny.aes;
import std.exception : enforce;
@safe:
private:
// The number of columns comprising a state in AES.
// This is a constant in AES. Value=4
const uint Nb = 4;
// state_t - array holding the intermediate results during decryption.
alias state_t = ubyte[4][4];
static const ubyte[256] sbox = [
//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 ];
static const ubyte[256] rsbox = [
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 ];
// The round constant word array, Rcon[i], contains the values given by
// x to the power (i-1) being powers of x
// (x is denoted as {02}) in the field GF(2^8)
static const ubyte[11] Rcon = [
0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 ];
/*
* Jordan Goulder points out in PR #12
* (https://github.com/kokke/tiny-AES-C/pull/12),
* that you can remove most of the elements in the Rcon array,
* because they are unused.
*
* From Wikipedia's article on the Rijndael key schedule
* @ https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
*
* "Only the first some of these constants are actually
* used -- up to rcon[10] for AES-128 (as 11 round keys are needed),
* up to rcon[8] for AES-192, up to rcon[7] for AES-256.
* rcon[0] is not used in AES algorithm."
*/
pure ubyte
xtime(uint x)
{
return cast(ubyte)(((x << 1) ^ (((x >> 7) & 1) * 0x1b)) & 0xFF);
}
// Xor into a destination from a src
void
XorWith(ubyte[] dest, in ubyte[] src)
{
// The block in AES is always 128bit no matter the key size
for (uint i = 0; i < AES_BLOCKLEN; ++i) {
dest[i] ^= src[i];
}
}
public:
// Block length in bytes - AES is 128b block only
const uint AES_BLOCKLEN = 16;
class AES {
private:
// The number of 32 bit words in a key.
uint Nk;
// The number of rounds in AES Cipher.
uint Nr;
// Key length in bytes
uint keylen;
ubyte[] RoundKey;
auto Iv = new ubyte[AES_BLOCKLEN];
// Encoded representation of caller's buffer
state_t state;
// This function produces Nb(Nr+1) round keys.
// The round keys are used in each round to decrypt the states.
void
KeyExpansion(in ubyte[] Key)
{
uint i, j, k;
ubyte[4] tempa; // Used for the column/row operations
// The first round key is the key itself.
for (i = 0; i < this.Nk; ++i) {
this.RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
this.RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
this.RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
this.RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
}
// All other round keys are found from the previous round keys.
for (i = this.Nk; i < Nb * (this.Nr + 1); ++i) {
k = (i - 1) * 4;
tempa[0] = this.RoundKey[k + 0];
tempa[1] = this.RoundKey[k + 1];
tempa[2] = this.RoundKey[k + 2];
tempa[3] = this.RoundKey[k + 3];
if ((i % this.Nk) == 0) {
// Shift the 4 bytes in a word to the left once.
// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
const ubyte u8tmp = tempa[0];
tempa[0] = tempa[1];
tempa[1] = tempa[2];
tempa[2] = tempa[3];
tempa[3] = u8tmp;
// Take a four-byte input word and
// apply the S-box to each of the four bytes to produce
// an output word.
tempa[0] = sbox[tempa[0]];
tempa[1] = sbox[tempa[1]];
tempa[2] = sbox[tempa[2]];
tempa[3] = sbox[tempa[3]];
tempa[0] = tempa[0] ^ Rcon[i / this.Nk];
}
// Special case for 256 bit AES
if (this.keylen == 32) {
if ((i % this.Nk) == 4) {
tempa[0] = sbox[tempa[0]];
tempa[1] = sbox[tempa[1]];
tempa[2] = sbox[tempa[2]];
tempa[3] = sbox[tempa[3]];
}
}
j = i * 4; k=(i - this.Nk) * 4;
this.RoundKey[j + 0] = this.RoundKey[k + 0] ^ tempa[0];
this.RoundKey[j + 1] = this.RoundKey[k + 1] ^ tempa[1];
this.RoundKey[j + 2] = this.RoundKey[k + 2] ^ tempa[2];
this.RoundKey[j + 3] = this.RoundKey[k + 3] ^ tempa[3];
}
}
// This function adds the round key to state.
// The round key is added to the state by an XOR function.
void
AddRoundKey(uint round)
{
for (uint i = 0; i < 4; ++i) {
for (uint j = 0; j < 4; ++j) {
(this.state)[i][j] ^=
this.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() {
for (uint i = 0; i < 4; ++i) {
for (uint j = 0; j < 4; ++j) {
this.state[j][i] = sbox[this.state[j][i]];
}
}
}
// 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() {
ubyte temp;
// Rotate first row 1 columns to left
temp = this.state[0][1];
this.state[0][1] = this.state[1][1];
this.state[1][1] = this.state[2][1];
this.state[2][1] = this.state[3][1];
this.state[3][1] = temp;
// Rotate second row 2 columns to left
temp = this.state[0][2];
this.state[0][2] = this.state[2][2];
this.state[2][2] = temp;
temp = this.state[1][2];
this.state[1][2] = this.state[3][2];
this.state[3][2] = temp;
// Rotate third row 3 columns to left
temp = this.state[0][3];
this.state[0][3] = this.state[3][3];
this.state[3][3] = this.state[2][3];
this.state[2][3] = this.state[1][3];
this.state[1][3] = temp;
}
// MixColumns function mixes the columns of the state matrix
void
MixColumns() {
ubyte Tmp, Tm, t;
for (uint i = 0; i < 4; ++i) {
t = this.state[i][0];
Tmp = this.state[i][0] ^ this.state[i][1] ^
this.state[i][2] ^ this.state[i][3] ;
Tm = this.state[i][0] ^ this.state[i][1] ; Tm = xtime(Tm);
this.state[i][0] ^= Tm ^ Tmp ;
Tm = this.state[i][1] ^ this.state[i][2] ; Tm = xtime(Tm);
this.state[i][1] ^= Tm ^ Tmp ;
Tm = this.state[i][2] ^ this.state[i][3] ; Tm = xtime(Tm);
this.state[i][2] ^= Tm ^ Tmp ;
Tm = this.state[i][3] ^ t ;
Tm = xtime(Tm);
this.state[i][3] ^= Tm ^ Tmp ;
}
}
// Multiply is used to multiply numbers in the field GF(2^8)
// Note: The last call to xtime() is unneeded,
// but often ends up generating a smaller binary
pure ubyte
Multiply(ubyte x, ubyte y) {
return
( ((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() {
ubyte a, b, c, d;
for (int i = 0; i < 4; ++i) {
a = this.state[i][0];
b = this.state[i][1];
c = this.state[i][2];
d = this.state[i][3];
this.state[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^
this.Multiply(c, 0x0d) ^ this.Multiply(d, 0x09);
this.state[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^
this.Multiply(c, 0x0b) ^ this.Multiply(d, 0x0d);
this.state[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^
this.Multiply(c, 0x0e) ^ this.Multiply(d, 0x0b);
this.state[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^
this.Multiply(c, 0x09) ^ this.Multiply(d, 0x0e);
}
}
// The SubBytes Function Substitutes the values in the
// state matrix with values in an S-box.
void
InvSubBytes() {
for (ubyte i = 0; i < 4; ++i) {
for (ubyte j = 0; j < 4; ++j) {
this.state[j][i] = rsbox[this.state[j][i]];
}
}
}
void
InvShiftRows() {
ubyte temp;
// Rotate first row 1 columns to right
temp = this.state[3][1];
this.state[3][1] = this.state[2][1];
this.state[2][1] = this.state[1][1];
this.state[1][1] = this.state[0][1];
this.state[0][1] = temp;
// Rotate second row 2 columns to right
temp = this.state[0][2];
this.state[0][2] = this.state[2][2];
this.state[2][2] = temp;
temp = this.state[1][2];
this.state[1][2] = this.state[3][2];
this.state[3][2] = temp;
// Rotate third row 3 columns to right
temp = this.state[0][3];
this.state[0][3] = this.state[1][3];
this.state[1][3] = this.state[2][3];
this.state[2][3] = this.state[3][3];
this.state[3][3] = temp;
}
// Cipher is the main function that encrypts the PlainText.
void
Cipher() {
// Add the First round key to the state before starting the rounds.
this.AddRoundKey(0);
// There will be Nr rounds.
// The first Nr-1 rounds are identical.
// These Nr rounds are executed in the loop below.
// Last one without MixColumns()
for (uint round = 1; ; ++round) {
this.SubBytes();
this.ShiftRows();
if (round == this.Nr) {
break;
}
this.MixColumns();
this.AddRoundKey(round);
}
// Add round key to last round
this.AddRoundKey(this.Nr);
}
void
InvCipher() {
// Add the First round key to the state before starting the rounds.
this.AddRoundKey(this.Nr);
// There will be Nr rounds.
// The first Nr-1 rounds are identical.
// These Nr rounds are executed in the loop below.
// Last one without InvMixColumn()
for (uint round = (this.Nr - 1); ; --round) {
this.InvShiftRows();
this.InvSubBytes();
this.AddRoundKey(round);
if (round == 0) {
break;
}
this.InvMixColumns();
}
}
// Transfer linear state from buffer into state_t format
void
buf_state(in ubyte[] buf) {
uint idx = 0;
for (uint i = 0; i < 4; ++i) {
for (uint j = 0; j < 4; ++j) {
this.state[i][j] = buf[idx++];
}
}
}
// Transfer state_t back into buf
void
state_buf(ubyte[] buf) {
uint idx = 0;
for (uint i = 0; i < 4; ++i) {
for (uint j = 0; j < 4; ++j) {
buf[idx++] = this.state[i][j];
}
}
}
public:
// For CBC, let them set our initialization vector
void
set_iv(in ubyte[] iv)
{
enforce(iv.length == AES_BLOCKLEN, "Wrong size of IV");
this.Iv[] = iv[];
}
void
ECB_encrypt(ubyte[] buf) {
// The next function call encrypts the PlainText with the Key using AES algorithm.
this.buf_state(buf);
this.Cipher();
this.state_buf(buf);
}
void
ECB_decrypt(ubyte[] buf) {
// The next function call decrypts the PlainText with the Key using AES algorithm.
this.buf_state(buf);
this.InvCipher();
this.state_buf(buf);
}
// Set up AES for a given strength of encryption
this(in uint nbit, in ubyte[] key) {
// Configure for key size. This includes
// expaaneidng RoundKey to the size needed for
// our key size
switch (nbit) {
case 128:
this.Nk = 4;
this.Nr = 10;
this.keylen = 16;
this.RoundKey.length = 176;
break;
case 192:
this.Nk = 6;
this.Nr = 12;
this.keylen = 24;
this.RoundKey.length = 208;
break;
case 256:
this.Nk = 8;
this.Nr = 14;
this.keylen = 32;
this.RoundKey.length = 240;
break;
default:
enforce(false, "Unsupported AES key size");
}
this.KeyExpansion(key);
}
void
CBC_encrypt_buffer(ubyte[] buf) {
auto Iv = this.Iv;
while (buf.length) {
XorWith(buf, Iv);
this.buf_state(buf);
Cipher();
this.state_buf(buf);
Iv = buf[0 .. AES_BLOCKLEN];
buf = buf[AES_BLOCKLEN .. $];
}
// Save latest Iv for next call
this.Iv = Iv;
}
void
CBC_decrypt_buffer(ubyte[] buf) {
auto storeNextIv = new ubyte[AES_BLOCKLEN];
while (buf.length) {
storeNextIv[] = buf[0 .. AES_BLOCKLEN];
this.buf_state(buf);
this.InvCipher();
this.state_buf(buf);
XorWith(buf, this.Iv);
this.Iv[] = storeNextIv[];
buf = buf[AES_BLOCKLEN .. $];
}
}
/*
* Symmetrical operation: same function for encrypting as for decrypting.
* Note any IV/nonce should never be reused with the same key
*/
void
CTR_xcrypt_buffer(ubyte[] buf) {
auto buffer = new ubyte[AES_BLOCKLEN];
uint bi = AES_BLOCKLEN;
for (size_t i = 0; i < buf.length; ++i, ++bi) {
/* we need to regen xor complement in buffer */
if (bi == AES_BLOCKLEN) {
this.buf_state(this.Iv);
Cipher();
this.state_buf(buffer);
/* Increment Iv and handle overflow */
for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi) {
/* inc will overflow */
if (this.Iv[bi] == 255) {
this.Iv[bi] = 0;
continue;
}
this.Iv[bi] += 1;
break;
}
bi = 0;
}
buf[i] ^= buffer[bi];
}
}
}
unittest {
import tiny.fmt : hexstr;
// In-place ECB encryption
const ubyte[] k1 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
auto a1 = new AES(128, k1);
ubyte[] k2 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
a1.ECB_encrypt(k2);
auto k3 = hexstr(k2);
assert(k3 == "66e94bd4ef8a2c3b884cfa59ca342b2e");
// Initialization vector, CBC mode
auto a2 = new AES(128, k1);
a2.set_iv(k1);
ubyte[] k4 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
a2.CBC_encrypt_buffer(k4);
assert(hexstr(k4) == "66e94bd4ef8a2c3b884cfa59ca342b2e");
ubyte[] k5 = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
a2.CBC_encrypt_buffer(k5);
assert(hexstr(k5) == "f795bd4a52e29ed713d313fa20e98dbc");
}
version(unittest) {
void main() {
}
}