easy-wallet/tests/test_crypto.py

import sys
import os
import base64
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))

import pytest
from src.crypto import pw_encode, pw_decode, _derive_key

SECRETSCAN_URL = "https://secretscan.org/Bitcoin?address={}"

PASSWORD = "correct_horse_battery_staple"
PLAINTEXT = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"


# --- Key derivation ---

def test_derive_key_is_32_bytes():
    key = _derive_key(PASSWORD)
    assert len(key) == 32


def test_derive_key_deterministic():
    assert _derive_key(PASSWORD) == _derive_key(PASSWORD)


def test_derive_key_different_passwords_differ():
    assert _derive_key("password1") != _derive_key("password2")


def test_derive_key_returns_bytes():
    assert isinstance(_derive_key(PASSWORD), bytes)


# --- pw_encode output format ---

def test_pw_encode_returns_string():
    result = pw_encode(PLAINTEXT, PASSWORD)
    assert isinstance(result, str)


def test_pw_encode_is_valid_base64():
    result = pw_encode(PLAINTEXT, PASSWORD)
    raw = base64.b64decode(result)
    # Must contain at least 16 bytes IV + 16 bytes (one AES block)
    assert len(raw) >= 32


def test_pw_encode_includes_iv():
    # Encoded payload = IV (16 bytes) + ciphertext; base64 of 32+ bytes
    result = pw_encode(PLAINTEXT, PASSWORD)
    raw = base64.b64decode(result)
    assert len(raw) >= 16


# --- Random IV: same inputs produce different ciphertext each call ---

def test_pw_encode_random_iv_produces_unique_ciphertext():
    c1 = pw_encode(PLAINTEXT, PASSWORD)
    c2 = pw_encode(PLAINTEXT, PASSWORD)
    assert c1 != c2


def test_pw_encode_random_iv_different_on_three_calls():
    outputs = {pw_encode(PLAINTEXT, PASSWORD) for _ in range(5)}
    assert len(outputs) == 5


# --- Round-trip ---

def test_pw_round_trip_basic():
    ciphertext = pw_encode(PLAINTEXT, PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == PLAINTEXT


def test_pw_round_trip_empty_string():
    ciphertext = pw_encode("", PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == ""


def test_pw_round_trip_unicode():
    text = "passphrase: résumé café 日本語 🔑"
    ciphertext = pw_encode(text, PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == text


def test_pw_round_trip_long_text():
    text = "a" * 1000
    ciphertext = pw_encode(text, PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == text


def test_pw_round_trip_special_characters():
    text = '!@#$%^&*()_+-=[]{}|;\':",./<>?`~\\'
    ciphertext = pw_encode(text, PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == text


def test_pw_round_trip_private_key_wif():
    # Simulate encrypting a real WIF-looking private key
    wif = "KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU74NMTptX4"
    ciphertext = pw_encode(wif, PASSWORD)
    assert pw_decode(ciphertext, PASSWORD) == wif


# --- Wrong password / corrupted data ---

def test_pw_decode_wrong_password_raises_value_error():
    ciphertext = pw_encode(PLAINTEXT, PASSWORD)
    with pytest.raises(ValueError):
        pw_decode(ciphertext, "wrong_password")


def test_pw_decode_wrong_password_error_message():
    ciphertext = pw_encode(PLAINTEXT, PASSWORD)
    with pytest.raises(ValueError, match="Incorrect password or corrupted data"):
        pw_decode(ciphertext, "wrong_password")


def test_pw_decode_empty_password_still_encrypts():
    # Empty password is technically valid; round-trip must work
    ciphertext = pw_encode(PLAINTEXT, "")
    assert pw_decode(ciphertext, "") == PLAINTEXT


def test_pw_decode_corrupted_not_base64_raises():
    with pytest.raises(ValueError):
        pw_decode("!!!not_valid_base64!!!", PASSWORD)


def test_pw_decode_too_short_data_raises():
    # 15 bytes = less than an IV (16 bytes), cannot contain any ciphertext
    short = base64.b64encode(b"x" * 15).decode()
    with pytest.raises(ValueError):
        pw_decode(short, PASSWORD)


def test_pw_decode_only_iv_no_ciphertext_raises():
    # Exactly 16 bytes: IV with zero ciphertext → unpadding must fail
    iv_only = base64.b64encode(b"A" * 16).decode()
    with pytest.raises(ValueError):
        pw_decode(iv_only, PASSWORD)


# --- SecretScan integration note ---

def test_crypto_print_secretscan(capsys):
    """Document that encrypted wallet seeds can be verified via SecretScan after decryption."""
    ciphertext = pw_encode(PLAINTEXT, PASSWORD)
    decrypted = pw_decode(ciphertext, PASSWORD)
    # Once decrypted, the seed can be used to derive addresses verifiable on SecretScan
    url = SECRETSCAN_URL.format("bc1qcr8te4kr609gcawutmrza0j4xv80jy8z306fyu")
    print(f"\n[Crypto] Encrypted seed round-trip OK")
    print(f"[Crypto] Derived addresses verifiable at: {url}")
    captured = capsys.readouterr()
    assert "secretscan.org" in captured.out
    assert decrypted == PLAINTEXT