XOR Operatsiyasi

XOR (Eksklyuziv OR) nima?

XOR — ikki bitni taqqoslaydigan mantiqiy operatsiya. Faqat bittasi 1 bo'lganda natija 1.

XOR ning muhim xususiyatlari

Qanday shifrlaydi?

# XOR shifrlash
def xor_encrypt(plaintext, key):
    # Kalit takrorlanadi (cycling)
    result = []
    for i, char in enumerate(plaintext):
        encrypted_byte = ord(char) ^ ord(key[i % len(key)])
        result.append(chr(encrypted_byte))
    return ''.join(result)

def xor_decrypt(ciphertext, key):
    # XOR o'zi o'zining teskarisi!
    return xor_encrypt(ciphertext, key)

# Misol
matn = "Salom"
kalit = "K"
encrypted = ''.join(chr(ord(c) ^ ord(kalit)) for c in matn)
print("Shifrlangan:", encrypted)
decrypted = ''.join(chr(ord(c) ^ ord(kalit)) for c in encrypted)
print("Deshifrlangan:", decrypted)  # Salom

Python bytes bilan

# Hex ma'lumot bilan ishlash
ciphertext_hex = "1c 37 36 36 71"
key_byte = 0x42

ciphertext = bytes.fromhex(ciphertext_hex.replace(' ', ''))
plaintext = bytes([b ^ key_byte for b in ciphertext])
print(plaintext.decode('utf-8', errors='replace'))

# Ko'p baytli kalit bilan
def xor_bytes(data: bytes, key: bytes) -> bytes:
    return bytes([data[i] ^ key[i % len(key)] for i in range(len(data))])

data = b"\x9d\xc4\xc5\xc1"
key = b"KEY"
result = xor_bytes(data, key)
print(result)

Single-byte XOR ni qanday buzish mumkin?

# Single-byte XOR cracking
def crack_single_xor(ciphertext: bytes) -> tuple:
    # Eng yaxshi kalitni qidirish (ingliz matni bo'lsa)
    best_key = 0
    best_score = 0
    
    english_freqs = "etaoinshrdlu"  # Eng ko'p uchraydigan harflar
    
    for key in range(256):
        decrypted = bytes([b ^ key for b in ciphertext])
        try:
            text = decrypted.decode('utf-8')
            score = sum(1 for c in text.lower() if c in english_freqs)
            if score > best_score:
                best_score = score
                best_key = key
        except:
            continue
    
    return best_key, bytes([b ^ best_key for b in ciphertext])

ct = bytes.fromhex("2b0e0b0b5c7976...")
key, pt = crack_single_xor(ct)
print(f"Kalit: {key} (0x{key:02x})")
print(f"Plaintext: {pt}")