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aes.c
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aes.c
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/*
*
* Chinese Academy of Sciences
* State Key Laboratory of Information Security
* Institute of Information Engineering
*
* Copyright (C) 2016 Chinese Academy of Sciences
*
* LuoPeng, [email protected]
* Updated in Oct 2016
* Updated in Jan 2017, update muliple function on GF(2^8).
*
*/
#include <stdint.h>
#include <stdio.h>
#include "aes.h"
/*
* round constants
*/
static uint8_t RC[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};
/*
* Sbox
*/
static uint8_t SBOX[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};
/*
* Inverse Sboxs
*/
static uint8_t INV_SBOX[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};
/**
* https://en.wikipedia.org/wiki/Finite_field_arithmetic
* Multiply two numbers in the GF(2^8) finite field defined
* by the polynomial x^8 + x^4 + x^3 + x + 1 = 0
* We do use mul2(int8_t a) but not mul(uint8_t a, uint8_t b)
* just in order to get a higher speed.
*/
static inline uint8_t mul2(uint8_t a) {
return (a&0x80) ? ((a<<1)^0x1b) : (a<<1);
}
/**
* @purpose: ShiftRows
* @descrption:
* Row0: s0 s4 s8 s12 <<< 0 byte
* Row1: s1 s5 s9 s13 <<< 1 byte
* Row2: s2 s6 s10 s14 <<< 2 bytes
* Row3: s3 s7 s11 s15 <<< 3 bytes
*/
static void shift_rows(uint8_t *state) {
uint8_t temp;
// row1
temp = *(state+1);
*(state+1) = *(state+5);
*(state+5) = *(state+9);
*(state+9) = *(state+13);
*(state+13) = temp;
// row2
temp = *(state+2);
*(state+2) = *(state+10);
*(state+10) = temp;
temp = *(state+6);
*(state+6) = *(state+14);
*(state+14) = temp;
// row3
temp = *(state+15);
*(state+15) = *(state+11);
*(state+11) = *(state+7);
*(state+7) = *(state+3);
*(state+3) = temp;
}
/**
* @purpose: Inverse ShiftRows
* @description
* Row0: s0 s4 s8 s12 >>> 0 byte
* Row1: s1 s5 s9 s13 >>> 1 byte
* Row2: s2 s6 s10 s14 >>> 2 bytes
* Row3: s3 s7 s11 s15 >>> 3 bytes
*/
static void inv_shift_rows(uint8_t *state) {
uint8_t temp;
// row1
temp = *(state+13);
*(state+13) = *(state+9);
*(state+9) = *(state+5);
*(state+5) = *(state+1);
*(state+1) = temp;
// row2
temp = *(state+14);
*(state+14) = *(state+6);
*(state+6) = temp;
temp = *(state+10);
*(state+10) = *(state+2);
*(state+2) = temp;
// row3
temp = *(state+3);
*(state+3) = *(state+7);
*(state+7) = *(state+11);
*(state+11) = *(state+15);
*(state+15) = temp;
}
void aes_key_schedule_128(const uint8_t *key, uint8_t *roundkeys) {
uint8_t temp[4];
uint8_t *last4bytes; // point to the last 4 bytes of one round
uint8_t *lastround;
uint8_t i;
for (i = 0; i < 16; ++i) {
*roundkeys++ = *key++;
}
last4bytes = roundkeys-4;
for (i = 0; i < AES_ROUNDS; ++i) {
// k0-k3 for next round
temp[3] = SBOX[*last4bytes++];
temp[0] = SBOX[*last4bytes++];
temp[1] = SBOX[*last4bytes++];
temp[2] = SBOX[*last4bytes++];
temp[0] ^= RC[i];
lastround = roundkeys-16;
*roundkeys++ = temp[0] ^ *lastround++;
*roundkeys++ = temp[1] ^ *lastround++;
*roundkeys++ = temp[2] ^ *lastround++;
*roundkeys++ = temp[3] ^ *lastround++;
// k4-k7 for next round
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
// k8-k11 for next round
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
// k12-k15 for next round
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
*roundkeys++ = *last4bytes++ ^ *lastround++;
}
}
void aes_encrypt_128(const uint8_t *roundkeys, const uint8_t *plaintext, uint8_t *ciphertext) {
uint8_t tmp[16], t;
uint8_t i, j;
// first AddRoundKey
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(ciphertext+i) = *(plaintext+i) ^ *roundkeys++;
}
// 9 rounds
for (j = 1; j < AES_ROUNDS; ++j) {
// SubBytes
for (i = 0; i < AES_BLOCK_SIZE; ++i) {
*(tmp+i) = SBOX[*(ciphertext+i)];
}
shift_rows(tmp);
/*
* MixColumns
* [02 03 01 01] [s0 s4 s8 s12]
* [01 02 03 01] . [s1 s5 s9 s13]
* [01 01 02 03] [s2 s6 s10 s14]
* [03 01 01 02] [s3 s7 s11 s15]
*/
for (i = 0; i < AES_BLOCK_SIZE; i+=4) {
t = tmp[i] ^ tmp[i+1] ^ tmp[i+2] ^ tmp[i+3];
ciphertext[i] = mul2(tmp[i] ^ tmp[i+1]) ^ tmp[i] ^ t;
ciphertext[i+1] = mul2(tmp[i+1] ^ tmp[i+2]) ^ tmp[i+1] ^ t;
ciphertext[i+2] = mul2(tmp[i+2] ^ tmp[i+3]) ^ tmp[i+2] ^ t;
ciphertext[i+3] = mul2(tmp[i+3] ^ tmp[i] ) ^ tmp[i+3] ^ t;
}
// AddRoundKey
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(ciphertext+i) ^= *roundkeys++;
}
}
// last round
for (i = 0; i < AES_BLOCK_SIZE; ++i) {
*(ciphertext+i) = SBOX[*(ciphertext+i)];
}
shift_rows(ciphertext);
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(ciphertext+i) ^= *roundkeys++;
}
}
void aes_decrypt_128(const uint8_t *roundkeys, const uint8_t *ciphertext, uint8_t *plaintext) {
uint8_t tmp[16];
uint8_t t, u, v;
uint8_t i, j;
roundkeys += 160;
// first round
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(plaintext+i) = *(ciphertext+i) ^ *(roundkeys+i);
}
roundkeys -= 16;
inv_shift_rows(plaintext);
for (i = 0; i < AES_BLOCK_SIZE; ++i) {
*(plaintext+i) = INV_SBOX[*(plaintext+i)];
}
for (j = 1; j < AES_ROUNDS; ++j) {
// Inverse AddRoundKey
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(tmp+i) = *(plaintext+i) ^ *(roundkeys+i);
}
/*
* Inverse MixColumns
* [0e 0b 0d 09] [s0 s4 s8 s12]
* [09 0e 0b 0d] . [s1 s5 s9 s13]
* [0d 09 0e 0b] [s2 s6 s10 s14]
* [0b 0d 09 0e] [s3 s7 s11 s15]
*/
for (i = 0; i < AES_BLOCK_SIZE; i+=4) {
t = tmp[i] ^ tmp[i+1] ^ tmp[i+2] ^ tmp[i+3];
plaintext[i] = t ^ tmp[i] ^ mul2(tmp[i] ^ tmp[i+1]);
plaintext[i+1] = t ^ tmp[i+1] ^ mul2(tmp[i+1] ^ tmp[i+2]);
plaintext[i+2] = t ^ tmp[i+2] ^ mul2(tmp[i+2] ^ tmp[i+3]);
plaintext[i+3] = t ^ tmp[i+3] ^ mul2(tmp[i+3] ^ tmp[i]);
u = mul2(mul2(tmp[i] ^ tmp[i+2]));
v = mul2(mul2(tmp[i+1] ^ tmp[i+3]));
t = mul2(u ^ v);
plaintext[i] ^= t ^ u;
plaintext[i+1] ^= t ^ v;
plaintext[i+2] ^= t ^ u;
plaintext[i+3] ^= t ^ v;
}
// Inverse ShiftRows
inv_shift_rows(plaintext);
// Inverse SubBytes
for (i = 0; i < AES_BLOCK_SIZE; ++i) {
*(plaintext+i) = INV_SBOX[*(plaintext+i)];
}
roundkeys -= 16;
}
// last AddRoundKey
for ( i = 0; i < AES_BLOCK_SIZE; ++i ) {
*(plaintext+i) ^= *(roundkeys+i);
}
}