# AES.py

# AES S-box and Inverse S-box
S_BOX = [
    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
]


INV_S_BOX = [
    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
]


# Round constants
RCON = [
    0x00, 0x01, 0x02, 0x04, 0x08, 0x10,
    0x20, 0x40, 0x80, 0x1B, 0x36
]

# Utility Functions
def sub_bytes(state):
    return [S_BOX[b] for b in state]

def inv_sub_bytes(state):
    return [INV_S_BOX[b] for b in state]

def shift_rows(state):
    return [
        state[0], state[5], state[10], state[15],
        state[4], state[9], state[14], state[3],
        state[8], state[13], state[2], state[7],
        state[12], state[1], state[6], state[11],
    ]

def inv_shift_rows(state):
    return [
        state[0], state[13], state[10], state[7],
        state[4], state[1], state[14], state[11],
        state[8], state[5], state[2], state[15],
        state[12], state[9], state[6], state[3],
    ]

def xtime(a):
    return ((a << 1) ^ 0x1b) & 0xff if a & 0x80 else (a << 1)

def mix_single_column(a):
    return [
        xtime(a[0]) ^ xtime(a[1]) ^ a[1] ^ a[2] ^ a[3],
        xtime(a[1]) ^ xtime(a[2]) ^ a[2] ^ a[3] ^ a[0],
        xtime(a[2]) ^ xtime(a[3]) ^ a[3] ^ a[0] ^ a[1],
        xtime(a[3]) ^ xtime(a[0]) ^ a[0] ^ a[1] ^ a[2],
    ]

def mix_columns(state):
    new_state = []
    for i in range(4):
        col = state[i::4]
        new_col = mix_single_column(col)
        for j in range(4):
            new_state.append(new_col[j])
    return new_state

def add_round_key(state, round_key):
    return [b ^ rk for b, rk in zip(state, round_key)]

def key_expansion(key):
    key_symbols = [ord(symbol) for symbol in key]
    if len(key_symbols) < 16:
        key_symbols += [0x01] * (16 - len(key_symbols))  # padding
    key_schedule = key_symbols[:]
    for i in range(4, 4 * (10 + 1)):
        temp = key_schedule[(i-1)*4:i*4]
        if i % 4 == 0:
            temp = [S_BOX[b] for b in temp[1:] + temp[:1]]
            temp[0] ^= RCON[i//4]
        word = [a ^ b for a, b in zip(temp, key_schedule[(i-4)*4:(i-3)*4])]
        key_schedule += word
    return [key_schedule[i:i+16] for i in range(0, len(key_schedule), 16)]

def aes_encrypt(plaintext, key):
    state = [ord(c) for c in plaintext]
    if len(state) < 16:
        state += [0x00] * (16 - len(state))
    keys = key_expansion(key)
    state = add_round_key(state, keys[0])
    for round in range(1, 10):
        state = sub_bytes(state)
        state = shift_rows(state)
        state = mix_columns(state)
        state = add_round_key(state, keys[round])
    state = sub_bytes(state)
    state = shift_rows(state)
    state = add_round_key(state, keys[10])
    return ''.join(format(b, '02X') for b in state)

def aes_decrypt(ciphertext_hex, key):
    state = [int(ciphertext_hex[i:i+2], 16) for i in range(0, len(ciphertext_hex), 2)]
    keys = key_expansion(key)
    state = add_round_key(state, keys[10])
    for round in range(9, 0, -1):
        state = inv_shift_rows(state)
        state = inv_sub_bytes(state)
        state = add_round_key(state, keys[round])
        # no inv_mix_columns for last round
    state = inv_shift_rows(state)
    state = inv_sub_bytes(state)
    state = add_round_key(state, keys[0])
    return ''.join(chr(b) for b in state if b != 0x00)

__all__ = ['aes_encrypt', 'aes_decrypt']
