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| 1 | +"""LegacyCryptoService implementation for pynacl.""" |
| 2 | + |
| 3 | +from dataclasses import dataclass |
| 4 | +from typing import Dict, Optional, Sequence |
| 5 | + |
| 6 | +import base58 |
| 7 | + |
| 8 | +try: |
| 9 | + import nacl.bindings |
| 10 | + import nacl.exceptions |
| 11 | + import nacl.utils |
| 12 | +except ImportError as err: |
| 13 | + raise ImportError( |
| 14 | + "Legacy implementation requires 'legacy' extra to be installed" |
| 15 | + ) from err |
| 16 | +from pydid import VerificationMethod |
| 17 | + |
| 18 | +from didcomm_messaging.crypto.base import ( |
| 19 | + PublicKey, |
| 20 | + SecretKey, |
| 21 | + SecretsManager, |
| 22 | +) |
| 23 | +from didcomm_messaging.crypto.jwe import JweEnvelope |
| 24 | +from didcomm_messaging.multiformats import multibase, multicodec |
| 25 | + |
| 26 | +from . import crypto |
| 27 | +from .base import LegacyCryptoService, LegacyUnpackResult, RecipData |
| 28 | + |
| 29 | + |
| 30 | +@dataclass |
| 31 | +class KeyPair(SecretKey): |
| 32 | + """Keys.""" |
| 33 | + |
| 34 | + verkey: bytes |
| 35 | + sigkey: bytes |
| 36 | + |
| 37 | + @property |
| 38 | + def verkey_b58(self) -> str: |
| 39 | + """Return base58 encoding of verkey.""" |
| 40 | + return base58.b58encode(self.verkey).decode() |
| 41 | + |
| 42 | + @property |
| 43 | + def kid(self) -> str: |
| 44 | + """Get the key ID.""" |
| 45 | + return self.verkey_b58 |
| 46 | + |
| 47 | + |
| 48 | +@dataclass |
| 49 | +class EdPublicKey(PublicKey): |
| 50 | + """Simple public key representation as base58 encoded str.""" |
| 51 | + |
| 52 | + value: bytes |
| 53 | + |
| 54 | + @classmethod |
| 55 | + def from_verification_method(cls, vm: VerificationMethod) -> "EdPublicKey": |
| 56 | + """Create a Key instance from a DID Document Verification Method.""" |
| 57 | + key_bytes = cls.key_bytes_from_verification_method(vm) |
| 58 | + return EdPublicKey(key_bytes) |
| 59 | + |
| 60 | + @property |
| 61 | + def key(self) -> str: |
| 62 | + """Return base58 encoded key.""" |
| 63 | + return base58.b58encode(self.value).decode() |
| 64 | + |
| 65 | + @property |
| 66 | + def kid(self) -> str: |
| 67 | + """Get the key ID.""" |
| 68 | + return self.key |
| 69 | + |
| 70 | + @property |
| 71 | + def multikey(self) -> str: |
| 72 | + """Get the key in multikey format.""" |
| 73 | + return multibase.encode( |
| 74 | + multicodec.wrap("ed25519-pub", base58.b58decode(self.key)), "base58btc" |
| 75 | + ) |
| 76 | + |
| 77 | + |
| 78 | +class NaclLegacyCryptoService(LegacyCryptoService[EdPublicKey, KeyPair]): |
| 79 | + """Legacy crypto service using pynacl.""" |
| 80 | + |
| 81 | + def kid_to_public_key(self, kid: str): |
| 82 | + """Get a public key from a kid. |
| 83 | +
|
| 84 | + In DIDComm v1, kids are the base58 encoded keys. |
| 85 | + """ |
| 86 | + return EdPublicKey(base58.b58decode(kid)) |
| 87 | + |
| 88 | + async def pack_message( |
| 89 | + self, |
| 90 | + to_verkeys: Sequence[EdPublicKey], |
| 91 | + from_key: Optional[KeyPair], |
| 92 | + message: bytes, |
| 93 | + ) -> JweEnvelope: |
| 94 | + """Encode a message using the DIDComm v1 'pack' algorithm.""" |
| 95 | + packed = crypto.pack_message( |
| 96 | + message=message.decode(), |
| 97 | + to_verkeys=[vk.value for vk in to_verkeys], |
| 98 | + from_verkey=from_key.verkey if from_key else None, |
| 99 | + from_sigkey=from_key.sigkey if from_key else None, |
| 100 | + ) |
| 101 | + return JweEnvelope.deserialize(packed) |
| 102 | + |
| 103 | + def _extract_payload_key(self, recip_key: KeyPair, recip_data: RecipData): |
| 104 | + """Extract the payload key.""" |
| 105 | + pk = nacl.bindings.crypto_sign_ed25519_pk_to_curve25519(recip_key.verkey) |
| 106 | + sk = nacl.bindings.crypto_sign_ed25519_sk_to_curve25519(recip_key.sigkey) |
| 107 | + |
| 108 | + if recip_data.nonce and recip_data.enc_sender: |
| 109 | + sender_vk = nacl.bindings.crypto_box_seal_open( |
| 110 | + recip_data.enc_sender, pk, sk |
| 111 | + ).decode() |
| 112 | + sender_pk = nacl.bindings.crypto_sign_ed25519_pk_to_curve25519( |
| 113 | + crypto.b58_to_bytes(sender_vk) |
| 114 | + ) |
| 115 | + cek = nacl.bindings.crypto_box_open( |
| 116 | + recip_data.enc_cek, recip_data.nonce, sender_pk, sk |
| 117 | + ) |
| 118 | + else: |
| 119 | + sender_vk = None |
| 120 | + cek = nacl.bindings.crypto_box_seal_open(recip_data.enc_cek, pk, sk) |
| 121 | + return cek, sender_vk |
| 122 | + |
| 123 | + async def unpack_message( |
| 124 | + self, wrapper: JweEnvelope, recip_key: KeyPair, recip_data: RecipData |
| 125 | + ) -> LegacyUnpackResult: |
| 126 | + """Decode a message using DIDCvomm v1 'unpack' algorithm.""" |
| 127 | + cek, sender_vk = self._extract_payload_key(recip_key, recip_data) |
| 128 | + |
| 129 | + payload_bin = wrapper.ciphertext + wrapper.tag |
| 130 | + message = crypto.decrypt_plaintext( |
| 131 | + payload_bin, wrapper.protected_b64, wrapper.iv, cek |
| 132 | + ) |
| 133 | + return LegacyUnpackResult(message.encode(), recip_key.kid, sender_vk) |
| 134 | + |
| 135 | + |
| 136 | +class InMemSecretsManager(SecretsManager[KeyPair]): |
| 137 | + """In-memory secrets manager for ed25519 key pairs.""" |
| 138 | + |
| 139 | + def __init__(self): |
| 140 | + """Initialize the manager.""" |
| 141 | + self.secrets: Dict[str, KeyPair] = {} |
| 142 | + |
| 143 | + async def get_secret_by_kid(self, kid: str) -> Optional[KeyPair]: |
| 144 | + """Retrieve secret by kid.""" |
| 145 | + return self.secrets.get(kid) |
| 146 | + |
| 147 | + def create(self, seed: Optional[bytes] = None) -> KeyPair: |
| 148 | + """Create and store a new keypair.""" |
| 149 | + keys = KeyPair(*crypto.create_keypair(seed)) |
| 150 | + self.secrets[keys.kid] = keys |
| 151 | + return keys |
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