nanoclaw
eb56ed4aa2
Move source files into nested secpaste/ directory to fix module imports. This allows the package to be properly installed with pip and imported as 'import secpaste' or 'python -m secpaste.cli'. Changes: - Move all Python files into secpaste/secpaste/ structure - Add .gitignore for Python artifacts Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
66 lines
1.9 KiB
Python
66 lines
1.9 KiB
Python
"""AES-256-GCM cipher backend."""
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import os
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import base64
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from typing import Tuple
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from cryptography.hazmat.primitives.ciphers.aead import AESGCM
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from .base import CipherBackend
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class AESGCMCipher(CipherBackend):
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"""AES-256-GCM authenticated encryption."""
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def encrypt(self, plaintext: bytes) -> Tuple[bytes, str]:
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"""
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Encrypt using AES-256-GCM.
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Returns:
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Tuple of (nonce + ciphertext, base64url-encoded key)
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"""
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# Generate random 256-bit key
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key = AESGCM.generate_key(bit_length=256)
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aesgcm = AESGCM(key)
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# Generate random 96-bit nonce (recommended for GCM)
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nonce = os.urandom(12)
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# Encrypt and authenticate
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ciphertext = aesgcm.encrypt(nonce, plaintext, None)
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# Prepend nonce to ciphertext for storage
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encrypted_data = nonce + ciphertext
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# Encode key for URL fragment
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key_encoded = base64.urlsafe_b64encode(key).decode('ascii').rstrip('=')
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return encrypted_data, key_encoded
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def decrypt(self, ciphertext: bytes, key: str) -> bytes:
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"""
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Decrypt using AES-256-GCM.
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Args:
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ciphertext: Nonce (12 bytes) + encrypted data
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key: Base64url-encoded 256-bit key
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"""
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# Decode key (add padding if needed)
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padding = '=' * (4 - len(key) % 4) if len(key) % 4 else ''
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key_bytes = base64.urlsafe_b64decode(key + padding)
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if len(key_bytes) != 32:
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raise ValueError("Invalid key length. Expected 32 bytes for AES-256.")
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# Extract nonce and ciphertext
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nonce = ciphertext[:12]
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encrypted = ciphertext[12:]
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# Decrypt
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aesgcm = AESGCM(key_bytes)
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plaintext = aesgcm.decrypt(nonce, encrypted, None)
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return plaintext
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def get_name(self) -> str:
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"""Return cipher name."""
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return "aes-256-gcm"
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