bhive.memo module¶
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class
bhive.memo.
Memo
(from_account=None, to_account=None, hive_instance=None)¶ Bases:
object
Deals with Memos that are attached to a transfer
- Parameters
A memo is encrypted with a shared secret derived from a private key of the sender and a public key of the receiver. Due to the underlying mathematics, the same shared secret can be derived by the private key of the receiver and the public key of the sender. The encrypted message is perturbed by a nonce that is part of the transmitted message.
from bhive.memo import Memo m = Memo("hiveeu", "wallet.xeroc") m.hive.wallet.unlock("secret") enc = (m.encrypt("foobar")) print(enc) >> {'nonce': '17329630356955254641', 'message': '8563e2bb2976e0217806d642901a2855'} print(m.decrypt(enc)) >> foobar
To decrypt a memo, simply use
from bhive.memo import Memo m = Memo() m.hive.wallet.unlock("secret") print(m.decrypt(op_data["memo"]))
if
op_data
being the payload of a transfer operation.Memo Keys
In Hive, memos are AES-256 encrypted with a shared secret between sender and receiver. It is derived from the memo private key of the sender and the memo public key of the receiver.
In order for the receiver to decode the memo, the shared secret has to be derived from the receiver’s private key and the senders public key.
The memo public key is part of the account and can be retrieved with the get_account call:
get_account <accountname> { [...] "options": { "memo_key": "GPH5TPTziKkLexhVKsQKtSpo4bAv5RnB8oXcG4sMHEwCcTf3r7dqE", [...] }, [...] }
while the memo private key can be dumped with dump_private_keys
Memo Message
The take the following form:
{ "from": "GPH5mgup8evDqMnT86L7scVebRYDC2fwAWmygPEUL43LjstQegYCC", "to": "GPH5Ar4j53kFWuEZQ9XhxbAja4YXMPJ2EnUg5QcrdeMFYUNMMNJbe", "nonce": "13043867485137706821", "message": "d55524c37320920844ca83bb20c8d008" }
The fields from and to contain the memo public key of sender and receiver. The nonce is a random integer that is used for the seed of the AES encryption of the message.
Encrypting a memo
The high level memo class makes use of the bhive wallet to obtain keys for the corresponding accounts.
from bhive.memo import Memo from bhive.account import Account memoObj = Memo( from_account=Account(from_account), to_account=Account(to_account) ) encrypted_memo = memoObj.encrypt(memo)
Decoding of a received memo
from getpass import getpass from bhive.block import Block from bhive.memo import Memo # Obtain a transfer from the blockchain block = Block(23755086) # block transaction = block["transactions"][3] # transactions op = transaction["operations"][0] # operation op_id = op[0] # operation type op_data = op[1] # operation payload # Instantiate Memo for decoding memo = Memo() # Unlock wallet memo.unlock_wallet(getpass()) # Decode memo # Raises exception if required keys not available in the wallet print(memo.decrypt(op_data["transfer"]))
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decrypt
(memo)¶ Decrypt a memo
- Parameters
memo (str) – encrypted memo message
- Returns
encrypted memo
- Return type
str
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encrypt
(memo, bts_encrypt=False)¶ Encrypt a memo
- Parameters
memo (str) – clear text memo message
- Returns
encrypted memo
- Return type
str
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unlock_wallet
(*args, **kwargs)¶ Unlock the library internal wallet