API updates:
- Mac class follows hashlib API: digest functions added and finalization no longer modifies state. - Encryptor and Decryptor now raise RuntimeError if still used after final. Documentation updated with the changes and further examples. Tests updated with the changes, new test module for error cases (test_raises). Docstrings improved.
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"""Tests for Encryptor and Decryptor finalization behavior.
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This module verifies that Encryptor and Decryptor objects become unusable
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after calling final(), preventing accidental misuse.
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"""
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import pytest
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from pyaegis import aegis256x4
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class TestEncryptorFinalization:
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"""Test that Encryptor becomes unusable after final()."""
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def test_update_after_final_raises(self):
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"""Test that calling update() after final() raises RuntimeError."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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# Encrypt some data and finalize
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encryptor.update(b"Hello, world!")
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tag = encryptor.final()
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# Attempting to update after final should raise RuntimeError
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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encryptor.update(b"More data")
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def test_final_after_final_raises(self):
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"""Test that calling final() after final() raises RuntimeError."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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# Encrypt some data and finalize
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encryptor.update(b"Hello, world!")
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tag = encryptor.final()
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# Attempting to call final again should raise RuntimeError
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with pytest.raises(
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RuntimeError, match="Cannot call final\\(\\) after final\\(\\)"
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):
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encryptor.final()
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def test_update_then_final_after_final_raises(self):
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"""Test that both update() and final() fail after final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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# Encrypt and finalize
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encryptor.update(b"Test data")
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tag = encryptor.final()
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# Both operations should fail
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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encryptor.update(b"More data")
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with pytest.raises(
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RuntimeError, match="Cannot call final\\(\\) after final\\(\\)"
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):
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encryptor.final()
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def test_properties_accessible_after_final(self):
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"""Test that properties like bytes_in and bytes_out are still accessible after final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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message = b"Hello, world!"
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encryptor.update(message)
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tag = encryptor.final()
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# Properties should still be accessible
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assert encryptor.bytes_in == len(message)
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assert encryptor.bytes_out == len(message) + len(tag)
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def test_empty_encryption_finalization(self):
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"""Test that finalization works correctly with no update() calls."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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# Finalize without any updates
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tag = encryptor.final()
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assert len(tag) == aegis256x4.MACBYTES
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# Should still be unusable after
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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encryptor.update(b"Data")
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class TestDecryptorFinalization:
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"""Test that Decryptor becomes unusable after final()."""
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def test_update_after_final_raises(self):
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"""Test that calling update() after final() raises RuntimeError."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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message = b"Hello, world!"
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# Encrypt first to get valid ciphertext and tag
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ct, tag = aegis256x4.encrypt_detached(key, nonce, message)
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# Now test decryption
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct)
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decryptor.final(tag)
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# Attempting to update after final should raise RuntimeError
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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decryptor.update(b"More ciphertext")
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def test_final_after_final_raises(self):
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"""Test that calling final() after final() raises RuntimeError."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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message = b"Hello, world!"
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# Encrypt first to get valid ciphertext and tag
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ct, tag = aegis256x4.encrypt_detached(key, nonce, message)
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# Now test decryption
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct)
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decryptor.final(tag)
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# Attempting to call final again should raise RuntimeError
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with pytest.raises(
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RuntimeError, match="Cannot call final\\(\\) after final\\(\\)"
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):
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decryptor.final(tag)
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def test_update_then_final_after_final_raises(self):
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"""Test that both update() and final() fail after final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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message = b"Test data"
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# Encrypt first
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ct, tag = aegis256x4.encrypt_detached(key, nonce, message)
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# Decrypt and finalize
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct)
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decryptor.final(tag)
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# Both operations should fail
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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decryptor.update(b"More ciphertext")
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with pytest.raises(
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RuntimeError, match="Cannot call final\\(\\) after final\\(\\)"
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):
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decryptor.final(tag)
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def test_properties_accessible_after_final(self):
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"""Test that properties like bytes_in and bytes_out are still accessible after final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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message = b"Hello, world!"
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# Encrypt first
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ct, tag = aegis256x4.encrypt_detached(key, nonce, message)
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# Decrypt
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct)
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decryptor.final(tag)
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# Properties should still be accessible
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assert decryptor.bytes_in == len(ct)
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assert decryptor.bytes_out == len(message)
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def test_empty_decryption_finalization(self):
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"""Test that finalization works correctly with no update() calls."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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# Encrypt empty message
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ct, tag = aegis256x4.encrypt_detached(key, nonce, b"")
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# Decrypt without any updates
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.final(tag) # Should work with empty ciphertext
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# Should still be unusable after
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with pytest.raises(
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RuntimeError, match="Cannot call update\\(\\) after final\\(\\)"
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):
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decryptor.update(b"Data")
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def test_failed_verification_still_finalizes(self):
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"""Test that even if verification fails, the object becomes unusable."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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message = b"Hello, world!"
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# Encrypt first
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ct, tag = aegis256x4.encrypt_detached(key, nonce, message)
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# Decrypt but use wrong tag
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct)
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# Try to finalize with invalid tag - should raise ValueError
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bad_tag = bytes(len(tag)) # All zeros
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with pytest.raises(ValueError, match="authentication failed"):
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decryptor.final(bad_tag)
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# Object should NOT be finalized on failure - should still be usable
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# This is a design decision: failed verification shouldn't lock the object
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# Let's verify current behavior
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try:
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decryptor.update(b"test")
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# If this doesn't raise, the object is still usable after failed verification
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# This might be the desired behavior
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except RuntimeError:
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# If this raises, failed verification also finalizes the object
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pass
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class TestMultipleChunksBeforeFinalization:
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"""Test that multiple update() calls work before final()."""
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def test_encryptor_multiple_updates(self):
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"""Test that Encryptor can handle multiple update() calls before final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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encryptor = aegis256x4.Encryptor(key, nonce)
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# Multiple updates
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encryptor.update(b"Hello, ")
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encryptor.update(b"world!")
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encryptor.update(b" More data.")
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# Should still work
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tag = encryptor.final()
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assert len(tag) == aegis256x4.MACBYTES
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# Now unusable
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with pytest.raises(RuntimeError):
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encryptor.update(b"More")
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def test_decryptor_multiple_updates(self):
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"""Test that Decryptor can handle multiple update() calls before final()."""
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key = aegis256x4.random_key()
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nonce = aegis256x4.random_nonce()
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# Encrypt in chunks
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encryptor = aegis256x4.Encryptor(key, nonce)
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ct1 = encryptor.update(b"Hello, ")
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ct2 = encryptor.update(b"world!")
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tag = encryptor.final()
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# Decrypt in chunks
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decryptor = aegis256x4.Decryptor(key, nonce)
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decryptor.update(ct1)
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decryptor.update(ct2)
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decryptor.final(tag)
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# Now unusable
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with pytest.raises(RuntimeError):
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decryptor.update(b"More")
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