lab3

from Crypto.Cipher import AES
import os

def AesBlockEncrypt(key, data, isFinalBlock = 0, padding = ''):
    if isFinalBlock and len(data) // 16 == 0:
        if padding == '':
            p = bytes(chr(16 - len(data) % 16), 'utf-8')
            data = data + p * (16 - len(data) % 16)
        else:
            data = data + bytes(padding, 'utf-8')
    return AES.new(key, AES.MODE_ECB).encrypt(data)

def AesBlockDecrypt(key, data):
    return AES.new(key, AES.MODE_ECB).decrypt(data)

def AesEncrypt(key, data, mode, iv = ''):
    ans = b''
    finalblock = data[16 * (len(data) // 16):]
    data = data[:16 * (len(data)) // 16]
    blocks = [data[i:i + 16] for i in range(0, len(data) - 15, 16)]
    if mode == 'ECB':
        for block in blocks:
            ans = ans + AesBlockEncrypt(key, block)
        if finalblock != b'':
            ans = ans + AesBlockEncrypt(key, finalblock, 1)

    elif mode == 'CBC':
        if iv == '':
            iv = os.urandom(16)
        blocks[0] = (int(blocks[0].hex(), 16) ^ int(iv.hex(), 16)).to_bytes(16, 'big')
        c = AesBlockEncrypt(key, blocks[0])
        ans = iv + c
        for i in range(1, len(blocks)):
            c = AesBlockEncrypt(key, (int(blocks[i].hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big'))
            ans = ans + c
        if finalblock != b'':
            p = bytes(chr(16 - len(finalblock) % 16), 'utf-8')
            finalblock = finalblock + p * (16 - len(finalblock) % 16)
            ans = ans + AesBlockEncrypt(key, (int(finalblock.hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big'))

    elif mode == 'CFB':
        if iv == '':
            iv = os.urandom(16)
        ans = ans + iv
        c = AesBlockEncrypt(key, iv)
        for i in range(0, len(blocks)):
            c = (int(blocks[i].hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big')
            ans = ans + c
            c = AesBlockEncrypt(key, c)
        if finalblock != b'':
            p = bytes(chr(16 - len(finalblock) % 16), 'utf-8')
            finalblock = finalblock + p * (16 - len(finalblock) % 16)
            ans = ans + (int(finalblock.hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big')

    elif mode == 'OFB':
        if iv == '':
            iv = os.urandom(16)
        ans = ans + iv
        c = AesBlockEncrypt(key, iv)
        for i in range(0, len(blocks)):
            ans = ans + (int(blocks[i].hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big')
            c = AesBlockEncrypt(key, c)
        if finalblock != b'':
            p = bytes(chr(16 - len(finalblock) % 16), 'utf-8')
            finalblock = finalblock + p * (16 - len(finalblock) % 16)
            ans = ans + (int(finalblock.hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big')

    elif mode == 'CTR':
        if iv == '':
            iv = os.urandom(16)
        ans = ans + iv
        for block in blocks:
            ans = ans + AesBlockEncrypt(key, (int(iv.hex(), 16) ^ int(block.hex(), 16)).to_bytes(16, 'big'))
            iv = (int(iv.hex(), 16) + 1).to_bytes(16, 'big')
        if finalblock != b'':
            p = bytes(chr(16 - len(finalblock) % 16), 'utf-8')
            finalblock = finalblock + p * (16 - len(finalblock) % 16)
            ans = ans + AesBlockEncrypt(key, (int(iv.hex(), 16) ^ int(finalblock.hex(), 16)).to_bytes(16, 'big'))

    return ans

def AesDecrypt(key, data, mode):
    ans = b''
    blocks = [data[i:i + 16] for i in range(0, len(data) - 15, 16)]

    if mode == 'ECB':
        for block in blocks:
            ans = ans + AesBlockDecrypt(key, block)

    elif mode == 'CBC':
        for i in range(1, len(blocks)):
            c = (int(AesBlockDecrypt(key, blocks[i]).hex(), 16) ^ int(blocks[i - 1].hex(), 16)).to_bytes(16, 'big')
            ans = ans + c

    elif mode == 'CFB':
        for i in range(1, len(blocks)):
            ans = ans + (int(blocks[i].hex(), 16) ^ int(AesBlockEncrypt(key, blocks[i - 1]).hex(), 16)).to_bytes(16, 'big')

    elif mode == 'OFB':
        iv = blocks[0]
        c = AesBlockEncrypt(key, iv)
        for i in range(1, len(blocks)):
            ans = ans + (int(blocks[i].hex(), 16) ^ int(c.hex(), 16)).to_bytes(16, 'big')
            c = AesBlockEncrypt(key, c)

    elif mode == 'CTR':
        iv = blocks[0]
        for i in range(1, len(blocks)):
            ans = ans + (int(AesBlockDecrypt(key, blocks[i]).hex(), 16) ^ int(iv.hex(), 16)).to_bytes(16, 'big')
            iv = (int(iv.hex(), 16) + 1).to_bytes(16, 'big')

    return ans