---

#!/usr/bin/env python3
import urllib.request
import json
import base64
import struct
import sys

BASE = sys.argv[1] if len(sys.argv) > 1 else "http://tasks.duckerz.ru:30030"

def post(path, payload):
    req = urllib.request.Request(BASE + path, data=json.dumps(payload).encode(),
        headers={"Content-Type": "application/json"}, method="POST")
    with urllib.request.urlopen(req, timeout=15) as resp:
        return json.loads(resp.read().decode())

def get(path):
    with urllib.request.urlopen(BASE + path, timeout=15) as resp:
        return json.loads(resp.read().decode())

def aes_ecb_victim(block16):
    r = post("/aes_ecb_tenant", {
        "who": "victim",
        "block_b64": base64.b64encode(block16).decode()
    })
    return base64.b64decode(r["cipher_b64"])

def main():
    # 1. FLAG_BLOB
    r = get("/flag")
    flag_blob = base64.b64decode(r["flag_blob"])
    FLAG_IV  = flag_blob[:12]
    FLAG_CT  = flag_blob[12:-16]
    FLAG_TAG = flag_blob[-16:]
    print(f"[+] FLAG_IV  = {FLAG_IV.hex()}")
    print(f"[+] FLAG_CT  = {FLAG_CT.hex()} ({len(FLAG_CT)} bytes)")

    # 2. Строим keystream для KEY_VICTIM с j0 = FLAG_IV || 00000001
    # CTR: начиная с j0 + 1 = FLAG_IV || 00000002
    # ks[0..15] = AES_ECB(VICTIM, FLAG_IV || 00000002)
    # ks[16..31] = AES_ECB(VICTIM, FLAG_IV || 00000003)
    # ks[32..] = AES_ECB(VICTIM, FLAG_IV || 00000004)[:...]
    
    ks = bytearray()
    counter = 2  # j0+1 = 00000002
    while len(ks) < len(FLAG_CT):
        block = FLAG_IV + counter.to_bytes(4, "big")
        ks_block = aes_ecb_victim(block)
        ks.extend(ks_block)
        counter += 1
        print(f"    keystream block {counter-2}: {ks_block.hex()}")
    
    ks = bytes(ks[:len(FLAG_CT)])
    print(f"[+] ks = {ks.hex()}")

    # 3. Расшифровываем
    FLAG_PT = bytes(a ^ b for a, b in zip(FLAG_CT, ks))
    print(f"[+] FLAG_PT = {FLAG_PT.hex()}")
    try:
        flag = FLAG_PT.decode()
        print(f"\n[***] FLAG: {flag}")
        return flag
    except Exception as e:
        print(f"[-] Не удалось декодировать: {e}")
        return None

if __name__ == "__main__":
    main()