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rust backup restore support (#3709)

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* Refactor key backup recovery to prepare for rust

* rust backup restore support

* Move export out of old crypto to api with re-export

* extract base64 utility

* add tests for base64 util

* more efficient regex

* fix typo
This commit is contained in:
Valere
2023-09-13 11:08:26 +02:00
committed by GitHub
parent 1b8507c060
commit 1503acb30a
12 changed files with 318 additions and 46 deletions
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109
spec/test-utils/test-data/generate-test-data.py
View File

@ -81,8 +81,7 @@ def main() -> None:
import {{ IDeviceKeys, IMegolmSessionData }} from "../../../src/@types/crypto";
import {{ IDownloadKeyResult }} from "../../../src";
import {{ KeyBackupInfo }} from "../../../src/crypto-api";
import {{ IKeyBackupSession }} from "../../../src/crypto/keybackup";
import {{ KeyBackupSession, KeyBackupInfo }} from "../../../src/crypto-api/keybackup";
/* eslint-disable comma-dangle */
@ -192,6 +191,7 @@ def build_test_data(user_data, prefix = "") -> str:
}
}
backed_up_room_key = encrypt_megolm_key_for_backup(additional_exported_room_key, backup_decryption_key.public_key())
backup_recovery_key = export_recovery_key(user_data["B64_BACKUP_DECRYPTION_KEY"])
@ -253,7 +253,7 @@ export const {prefix}MEGOLM_SESSION_DATA: IMegolmSessionData = {
};
/** The key from {prefix}MEGOLM_SESSION_DATA, encrypted for backup using `m.megolm_backup.v1.curve25519-aes-sha2` algorithm*/
export const {prefix}CURVE25519_KEY_BACKUP_DATA: IKeyBackupSession = {json.dumps(backed_up_room_key, indent=4)};
export const {prefix}CURVE25519_KEY_BACKUP_DATA: KeyBackupSession = {json.dumps(backed_up_room_key, indent=4)};
"""
@ -383,6 +383,7 @@ def build_exported_megolm_key() -> dict:
return megolm_export
def encrypt_megolm_key_for_backup(session_data: dict, backup_public_key: x25519.X25519PublicKey) -> dict:
"""
@ -447,6 +448,108 @@ def encrypt_megolm_key_for_backup(session_data: dict, backup_public_key: x25519.
return encrypted_key
def generate_encrypted_event_content(exported_key: dict, ed_key: ed25519.Ed25519PrivateKey, curve_key: x25519.X25519PrivateKey) -> tuple[dict, dict]:
"""
Encrypts an event using the given key in session export format.
Will not do any ratcheting, just encrypt at index 0.
"""
clear_event = {
"type": "m.room.message",
"room_id": "!room:id",
"sender": "@alice:localhost",
"content": {
"msgtype": "m.text",
"body": "Hello world"
}
}
session_key: str = exported_key["session_key"]
# Get the megolm R0 from the export format
decoded = base64.b64decode(session_key.encode("ascii"))
r0 = decoded[5:133]
hkdf = HKDF(
algorithm=hashes.SHA256(),
length=80,
salt=bytes(32),
info=b"MEGOLM_KEYS",
)
raw_key = hkdf.derive(r0)
aes_key = raw_key[:32]
mac = raw_key[32:64]
aes_iv = raw_key[64:80]
payload_json = {
"room_id": clear_event["room_id"],
"type": clear_event["type"],
"content": clear_event["content"]
}
payload_string = encode_canonical_json(payload_json)
cipher = Cipher(algorithms.AES(aes_key), modes.CBC(aes_iv))
encryptor = cipher.encryptor()
padder = padding.PKCS7(128).padder()
padded_data = padder.update(payload_string)
padded_data += padder.finalize()
ct = encryptor.update(padded_data) + encryptor.finalize()
# The ratchet index i, and the cipher-text​, are then packed
# into a message as described in Message format. Then the entire message
# (including the version bytes and all payload bytes) are passed through
# HMAC-SHA-256. The first 8 bytes of the MAC are appended to the message.
message = bytearray()
message += b'\x03'
# int tag for index
message += b'\x08'
# index is 0
message += b'\x00'
message += b'\x12'
# probably works only for short messages
message += len(ct).to_bytes(1, 'big')
# encrypted data
message += ct
h = hmac.HMAC(mac, hashes.SHA256())
h.update(message)
signature = h.finalize()
mac = signature[:8]
message += mac
# Finally, the authenticated message is signed using the Ed25519 keypair;
# the 64 byte signature is appended to the message
signature = ed_key.sign(bytes(message))
message += signature
cipher_text = encode_base64(message)
encrypted_payload = {
"algorithm" : "m.megolm.v1.aes-sha2",
"sender_key" : encode_base64(curve_key.public_key().public_bytes(Encoding.Raw, PublicFormat.Raw)),
"ciphertext" : cipher_text,
"session_id" : exported_key["session_id"],
"device_id" : "TEST_DEVICE"
}
encrypted_event = {
"type": "m.room.encrypted",
"room_id": "!room:id",
"sender": "@alice:localhost",
"content": encrypted_payload,
"event_id": "$event1",
"origin_server_ts": 1507753886000,
}
return clear_event, encrypted_event
def export_recovery_key(key_b64: str) -> str:
"""
Export a private recovery key as a recovery key that can be presented to users.

7
spec/test-utils/test-data/index.ts
View File

@ -5,8 +5,7 @@
import { IDeviceKeys, IMegolmSessionData } from "../../../src/@types/crypto";
import { IDownloadKeyResult } from "../../../src";
import { KeyBackupInfo } from "../../../src/crypto-api";
import { IKeyBackupSession } from "../../../src/crypto/keybackup";
import { KeyBackupSession, KeyBackupInfo } from "../../../src/crypto-api/keybackup";
/* eslint-disable comma-dangle */
@ -179,7 +178,7 @@ export const MEGOLM_SESSION_DATA: IMegolmSessionData = {
};
/** The key from MEGOLM_SESSION_DATA, encrypted for backup using `m.megolm_backup.v1.curve25519-aes-sha2` algorithm*/
export const CURVE25519_KEY_BACKUP_DATA: IKeyBackupSession = {
export const CURVE25519_KEY_BACKUP_DATA: KeyBackupSession = {
"first_message_index": 1,
"forwarded_count": 0,
"is_verified": false,
@ -359,7 +358,7 @@ export const BOB_MEGOLM_SESSION_DATA: IMegolmSessionData = {
};
/** The key from BOB_MEGOLM_SESSION_DATA, encrypted for backup using `m.megolm_backup.v1.curve25519-aes-sha2` algorithm*/
export const BOB_CURVE25519_KEY_BACKUP_DATA: IKeyBackupSession = {
export const BOB_CURVE25519_KEY_BACKUP_DATA: KeyBackupSession = {
"first_message_index": 1,
"forwarded_count": 0,
"is_verified": false,