Merging dev into main

paccrypt_algos/xchacha.py

@@ -0,0 +1,92 @@
+import os
+import base64
+from typing import Optional
+from Crypto.Cipher import ChaCha20_Poly1305
+from Crypto.Random import get_random_bytes
+from Crypto.Protocol.KDF import PBKDF2
+from Crypto.Hash import SHA256
+
+# === Constants ===
+SALT_LENGTH = 16
+NONCE_LENGTH = 24
+KEY_LENGTH = 32
+PBKDF2_ITERATIONS = 200_000
+TAG_LENGTH = 16
+
+# === Base64 Helpers ===
+def b64encode(data: bytes) -> str:
+    return base64.b64encode(data).decode('utf-8')
+
+def b64decode(data: str) -> bytes:
+    return base64.b64decode(data.encode('utf-8'))
+
+# === Key Derivation ===
+def derive_key(password: str, salt: bytes) -> bytes:
+    return PBKDF2(password, salt, dkLen=KEY_LENGTH, count=PBKDF2_ITERATIONS, hmac_hash_module=SHA256)
+
+# === Encrypt Text ===
+def encrypt_text(plaintext: str, password: str) -> str:
+    salt = get_random_bytes(SALT_LENGTH)
+    nonce = get_random_bytes(NONCE_LENGTH)
+    key = derive_key(password, salt)
+
+    cipher = ChaCha20_Poly1305.new(key=key, nonce=nonce)
+    ciphertext, tag = cipher.encrypt_and_digest(plaintext.encode('utf-8'))
+
+    final = salt + nonce + ciphertext + tag
+    return b64encode(final)
+
+# === Decrypt Text ===
+def decrypt_text(encrypted_b64: str, password: str) -> str:
+    raw = b64decode(encrypted_b64)
+    salt = raw[:SALT_LENGTH]
+    nonce = raw[SALT_LENGTH:SALT_LENGTH + NONCE_LENGTH]
+    tag = raw[-TAG_LENGTH:]
+    ciphertext = raw[SALT_LENGTH + NONCE_LENGTH:-TAG_LENGTH]
+
+    key = derive_key(password, salt)
+    cipher = ChaCha20_Poly1305.new(key=key, nonce=nonce)
+    plaintext = cipher.decrypt_and_verify(ciphertext, tag)
+
+    return plaintext.decode('utf-8')
+
+# === Encrypt File ===
+def encrypt_file(in_path, out_path, password: str, metadata: Optional[dict] = None):
+    with open(in_path, 'rb') as f:
+        plaintext = f.read()
+
+    salt = get_random_bytes(SALT_LENGTH)
+    nonce = get_random_bytes(NONCE_LENGTH)
+    key = derive_key(password, salt)
+
+    cipher = ChaCha20_Poly1305.new(key=key, nonce=nonce)
+    ciphertext, tag = cipher.encrypt_and_digest(plaintext)
+
+    with open(out_path, 'wb') as f:
+        f.write(salt + nonce + ciphertext + tag)
+
+# === Decrypt File ===
+def decrypt_file(in_path, out_path, password: str, metadata: Optional[dict] = None):
+    with open(in_path, 'rb') as f:
+        raw = f.read()
+
+    salt = raw[:SALT_LENGTH]
+    nonce = raw[SALT_LENGTH:SALT_LENGTH + NONCE_LENGTH]
+    tag = raw[-TAG_LENGTH:]
+    ciphertext = raw[SALT_LENGTH + NONCE_LENGTH:-TAG_LENGTH]
+
+    key = derive_key(password, salt)
+    cipher = ChaCha20_Poly1305.new(key=key, nonce=nonce)
+    plaintext = cipher.decrypt_and_verify(ciphertext, tag)
+
+    with open(out_path, 'wb') as f:
+        f.write(plaintext)
+
+# === Engine Name ===
+def get_name():
+    return "XChaCha20-Poly1305"
+
+
+if __name__ == "__main__":
+    from Crypto.Cipher.ChaCha20_Poly1305 import ChaCha20Poly1305Cipher as _test  # Force import to validate availability
+    from cryptography.exceptions import InvalidTag  # Still catchable for consistency