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// SBOX and INVERSE_SBOX are identical to what is used in AES

use crate::key_schedule;

pub static SBOX: [u8; 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 ];

pub static INVERSE_SBOX: [u8; 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 ];

pub fn u128_to_bytes(num: u128) -> [u8; 16] {
    return num.to_be_bytes();
}

pub fn swap_value(mut a: u8, mut b: u8) {
    let t = a.clone();
    a = b;
    b = t;
}

pub fn mix_block(block: &mut Vec<u8>, round_num: usize) {
    for i in 0..16 {
        for j in 0..16 {
            if i != j {
                block[i] ^= SBOX[block[j] as usize];
            }
        }
    }
    swap_value(block[(round_num + 11) % 16], block[(round_num + 6) % 16]);
    swap_value(block[(round_num + 5) % 16], block[(round_num + 14) % 16]);
    swap_value(block[(round_num + 1) % 16], block[(round_num + 15) % 16]);
    swap_value(block[(round_num + 10) % 16], block[(round_num + 12) % 16]);
    swap_value(block[(round_num + 9) % 16], block[(round_num + 3) % 16]);
    swap_value(block[(round_num + 4) % 16], block[(round_num + 7) % 16]);
    swap_value(block[(round_num + 2) % 16], block[(round_num + 8) % 16]);
    swap_value(block[round_num % 16], block[(round_num + 13) % 16]);
    for i in 0..16 {
        if i % 2 == 0 {
            block[i] = SBOX[block[i].rotate_left((i / 2) as u32) as usize]
        } else {
            block[i] = SBOX[block[i].rotate_right((i / 2) as u32) as usize];
        }
    }
    
}

pub fn inverse_mix_block(block: &mut Vec<u8>, round_num: usize) {
    for i in 0..16 {
        if i % 2 == 0 {
            block[i] = INVERSE_SBOX[block[i] as usize].rotate_right((i / 2) as u32);
        } else {
            block[i] = INVERSE_SBOX[block[i] as usize].rotate_left((i / 2) as u32);
        }
    }
    swap_value(block[(round_num + 11) % 16], block[(round_num + 6) % 16]);
    swap_value(block[(round_num + 5) % 16], block[(round_num + 14) % 16]);
    swap_value(block[(round_num + 1) % 16], block[(round_num + 15) % 16]);
    swap_value(block[(round_num + 10) % 16], block[(round_num + 12) % 16]);
    swap_value(block[(round_num + 9) % 16], block[(round_num + 3) % 16]);
    swap_value(block[(round_num + 4) % 16], block[(round_num + 7) % 16]);
    swap_value(block[(round_num + 2) % 16], block[(round_num + 8) % 16]);
    swap_value(block[round_num % 16], block[(round_num + 13) % 16]);
    for i in (0..16).rev() {
        for j in (0..16).rev() {
            if i != j {
                block[i] ^= SBOX[block[j] as usize];
            }
        }
    }
    
}

pub fn do_encrypt_round(block: &mut Vec<u8>, round_key: u128, round_num: usize) {
    let round_key_bytes = u128_to_bytes(round_key);
    mix_block(block, round_num);

    for i in 0..16 {
        block[i] ^= round_key_bytes[i];
    }
}

pub fn do_decrypt_round(block: &mut Vec<u8>, round_key: u128, round_num: usize) {
    let round_key_bytes = u128_to_bytes(round_key);
    
    for i in 0..16 {
        block[i] ^= round_key_bytes[i];
    }
    
    inverse_mix_block(block, round_num);
}

pub fn encrypt_block(block: &mut Vec<u8>, round_keys: &Vec<u128>) {
    let mut round_num = 0;
    for rk in round_keys {
        do_encrypt_round(block, *rk, round_num);
        round_num += 1;
    }
}

pub fn decrypt_block(block: &mut Vec<u8>, round_keys_reversed: &Vec<u128>) {
    let mut round_num = round_keys_reversed.len();
    for rk in round_keys_reversed {
        do_decrypt_round(block, *rk, round_num);
        round_num -= 1;
    }
}

pub fn encrypt_data(data: &mut Vec<u8>, key: &Vec<u8>) -> Vec<u8> {
    if data.len() % 16 != 0 {
        panic!("Data length must be a multiple of 16; You must pad your data before encrypting it")
    }

    let mut ciphertext: Vec<u8> = Vec::new();
    let mut blocks: Vec<Vec<u8>> = Vec::new();
    let round_keys = key_schedule::get_round_keys(key);

    for i in (0..data.len()).step_by(16) {
        let mut block = data[i..i+16].to_vec();
        encrypt_block(&mut block, &round_keys);
        blocks.push(block);
    }

    for mut block in blocks {
        ciphertext.append(&mut block);
    }

    return ciphertext;
}

pub fn decrypt_data(data: &mut Vec<u8>, key: &Vec<u8>) -> Vec<u8> {
    if data.len() % 16 != 0 {
        panic!("Data length must be a multiple of 16; You must pad your data before encrypting it")
    }

    let mut ciphertext: Vec<u8> = Vec::new();
    let mut blocks: Vec<Vec<u8>> = Vec::new();
    let reversed_round_keys = key_schedule::reverse_round_keys(key_schedule::get_round_keys(key));

    for i in (0..data.len()).step_by(16) {
        let mut block = data[i..i+16].to_vec();
        decrypt_block(&mut block, &reversed_round_keys);
        blocks.push(block);
    }
    for mut block in blocks {
        ciphertext.append(&mut block);
    }

    return ciphertext;
}