#include <stdio.h>
#include <stdint.h>

/* AES-128 simple implementation template and testing */

/*
Author: Ondrej Hladuvka, hladuond@fit.cvut.cz
Template: Jiri Bucek 2017
AES specification:
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
*/

/* AES Constants */

// forward sbox
const uint8_t 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
};

const uint8_t rCon[12] = {
    0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
};

/* AES state type */
typedef uint32_t t_state[4];

/* Helper functions */
void hexprint16(uint8_t *p) {
    for (int i = 0; i < 16; i++)
        printf("%02hhx ", p[i]);
    puts("");
}

void hexprintw(uint32_t w) {
    for (int i = 0; i < 32; i += 8)
        printf("%02hhx ", (w >> i) & 0xffU);
}

void hexprintws(uint32_t * p, int cnt) {
    for (int i = 0; i < cnt; i++)
        hexprintw(p[i]);
    puts("");
}
void printstate(t_state s) {
    hexprintw(s[0]);
    hexprintw(s[1]);
    hexprintw(s[2]);
    hexprintw(s[3]);
    puts("");
}

uint32_t word(uint8_t a0, uint8_t a1, uint8_t a2, uint8_t a3) {
    return a0 | (uint32_t)a1 << 8 | (uint32_t)a2 << 16 | (uint32_t)a3 << 24;
}

uint8_t wbyte(uint32_t w, int pos) {
    return (w >> (pos * 8)) & 0xff;
}

// **************** AES  functions ****************
uint32_t subWord(uint32_t w) {
    return word(SBOX[wbyte(w, 0)], SBOX[wbyte(w, 1)], SBOX[wbyte(w, 2)], SBOX[wbyte(w, 3)]);
}

void subBytes(t_state s) {
    unsigned char* p = reinterpret_cast<unsigned char*>(s);
    for (int i = 0; i < 16; ++i)
        p[i] = SBOX[p[i]];
}

void shiftRows(t_state s) {
    uint32_t tmp[4];

    tmp[0] = s[0] & 0x0000FF00;
    tmp[1] = s[1] & 0x0000FF00; 
    tmp[2] = s[2] & 0x0000FF00; 
    tmp[3] = s[3] & 0x0000FF00;

    s[0] = (s[0] & 0xFFFF00FF) | tmp[1];
    s[1] = (s[1] & 0xFFFF00FF) | tmp[2];
    s[2] = (s[2] & 0xFFFF00FF) | tmp[3];
    s[3] = (s[3] & 0xFFFF00FF) | tmp[0];

    tmp[0] = s[0] & 0x00FF0000;
    tmp[1] = s[1] & 0x00FF0000; 
    tmp[2] = s[2] & 0x00FF0000; 
    tmp[3] = s[3] & 0x00FF0000;

    s[0] = (s[0] & 0xFF00FFFF) | tmp[2];
    s[1] = (s[1] & 0xFF00FFFF) | tmp[3];
    s[2] = (s[2] & 0xFF00FFFF) | tmp[0];
    s[3] = (s[3] & 0xFF00FFFF) | tmp[1];

    tmp[0] = s[0] & 0xFF000000;
    tmp[1] = s[1] & 0xFF000000; 
    tmp[2] = s[2] & 0xFF000000; 
    tmp[3] = s[3] & 0xFF000000;

    s[0] = (s[0] & 0x00FFFFFF) | tmp[3];
    s[1] = (s[1] & 0x00FFFFFF) | tmp[0];
    s[2] = (s[2] & 0x00FFFFFF) | tmp[1];
    s[3] = (s[3] & 0x00FFFFFF) | tmp[2];
}

uint8_t xtime(uint8_t c) {
    uint8_t m = ((c & 0x80) >> 7) * 0x1B;
    return (c << 1) ^ m;
}

void mixColumns(t_state s) {
    for (int i = 0; i < 4; i++) {
        uint8_t a0 = wbyte(s[i], 0);
        uint8_t a1 = wbyte(s[i], 1);
        uint8_t a2 = wbyte(s[i], 2);
        uint8_t a3 = wbyte(s[i], 3);

        uint8_t r0 = xtime(a0) ^ xtime(a1) ^ a1 ^ a2 ^ a3;
        uint8_t r1 = xtime(a1) ^ xtime(a2) ^ a2 ^ a3 ^ a0;
        uint8_t r2 = xtime(a2) ^ xtime(a3) ^ a3 ^ a0 ^ a1;
        uint8_t r3 = xtime(a3) ^ xtime(a0) ^ a0 ^ a1 ^ a2;

        s[i] = word(r0, r1, r2, r3);
    }
}

/*
* Key expansion from 128bits (4*32b)
* to 11 round keys (11*4*32b)
* each round key is 4*32b
*/
void expandKey(uint8_t k[16], uint32_t ek[44]) {
    for (int i = 0; i < 4; i++) {
        ek[i] = word(k[4*i], k[4*i + 1], k[4*i + 2], k[4*i + 3]);
    }

    for (int i = 4; i < 44; i++) {
        uint32_t temp = ek[i - 1];
        if (i % 4 == 0) {
            // RotWord, SubWord, and XOR with Rcon
            temp = subWord((temp >> 8) | (temp << 24)) ^ rCon[i / 4];
        }
        ek[i] = ek[i - 4] ^ temp;
    }
}


/* Adding expanded round key (prepared before) */
void addRoundKey(t_state s, uint32_t ek[], short index) {
    for (int i = 0; i < 4; i++) {
        s[i] ^= ek[index + i];
    }
}

void aes128_4(uint8_t *in, uint8_t *out, uint32_t * expKey) {
    t_state state;

    state[0] = word(in[0],  in[1],  in[2],  in[3]);
    state[1] = word(in[4],  in[5],  in[6],  in[7]);
    state[2] = word(in[8],  in[9],  in[10], in[11]);
    state[3] = word(in[12], in[13], in[14], in[15]);

    addRoundKey(state, expKey, 0);
    for (int round = 0; round < 9; ++round) {
        subBytes(state);
        shiftRows(state);
        mixColumns(state);
        addRoundKey(state, expKey, round * 4 + 4);
    }

    subBytes(state);
    shiftRows(state);
    addRoundKey(state, expKey, 10 * 4);
    
    out[0]  = wbyte(state[0], 0);
    out[1]  = wbyte(state[0], 1);
    out[2]  = wbyte(state[0], 2);
    out[3]  = wbyte(state[0], 3);

    out[4]  = wbyte(state[1], 0);
    out[5]  = wbyte(state[1], 1);
    out[6]  = wbyte(state[1], 2);
    out[7]  = wbyte(state[1], 3);

    out[8]  = wbyte(state[2], 0);
    out[9]  = wbyte(state[2], 1);
    out[10] = wbyte(state[2], 2);
    out[11] = wbyte(state[2], 3);

    out[12] = wbyte(state[3], 0);
    out[13] = wbyte(state[3], 1);
    out[14] = wbyte(state[3], 2);
    out[15] = wbyte(state[3], 3);

}