memo.rst

Memo

Memo Keys

In BitShares, 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 publick 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 retreived 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.

Example

from bitsharesbase.memo import Memo
from bitsharesbase.account import PrivateKey, PublicKey

wifkey = "5....<wif>"
memo         = {
      "from": "GPH5mgup8evDqMnT86L7scVebRYDC2fwAWmygPEUL43LjstQegYCC",
      "to": "GPH5Ar4j53kFWuEZQ9XhxbAja4YXMPJ2EnUg5QcrdeMFYUNMMNJbe",
      "nonce": "13043867485137706821",
      "message": "d55524c37320920844ca83bb20c8d008"
    }
try :
    privkey = PrivateKey(wifkey)
    pubkey  = PublicKey(memo["from"], prefix=prefix)
    memomsg = Memo.decode_memo(privkey, pubkey, memo["nonce"], memo["message"])
except Exception as e:
    memomsg = "--cannot decode-- %s" % str(e)

Definitions