kmd.sign_transaction() fails when signing_address is specified

[oysterpack]

algosdk.kmd.sign_transaction() fails when signing_address arg is specified

Expected behaviour

Transaction should be signed using the private key corresponding to the specified signing_address

Actual behaviour

Exception is raised:

algosdk.error.KMDHTTPError: {
  "error": true,
  "message": "could not decode request body"

Steps to reproduce issue

1. start sandbox environment
2. Run the below code to reproduce

from pprint import pprint
from typing import cast

from algosdk import kmd
from algosdk.transaction import PaymentTxn
from algosdk.v2client.algod import AlgodClient

token = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
kmd_client = kmd.KMDClient(kmd_token=token, kmd_address='http://127.0.0.1:4002')
algod_client = AlgodClient(algod_token=token, algod_address='http://127.0.0.1:4001')

suggested_params = algod_client.suggested_params()
address = 'XDOV35UGGYEQHHN2UJSW4NQKS3IAFK2PYTGLK2CSUTDTXZ4EVRXTMEONEQ'
txn = PaymentTxn(sender=address, receiver=address, amt=0, sp=suggested_params)


def unencrypted_default_wallet_id() -> str:
    wallets = cast(list[dict[str, str]], kmd_client.list_wallets())
    for wallet in wallets:
        if wallet['name'] == 'unencrypted-default-wallet':
            return wallet['id']
    raise Exception('not found')


wallet_handle = kmd_client.init_wallet_handle(id=unencrypted_default_wallet_id(), password='')
# works when `signing_address` is None
signed_txn = kmd_client.sign_transaction(handle=wallet_handle, password='', txn=txn)
print('*** SUCCESSFULLY SIGNED TRANSACTION ***')
pprint(signed_txn.dictify())

print('*** Signing transaction with a `signing_address` arg fails')
# fails when `signing_address` is specified
signed_txn = kmd_client.sign_transaction(handle=wallet_handle, password='', txn=txn, signing_address=address) # raises exception

Your environment

py-algorand-sdk==2.0.0

./sandbox version

algod version
12885032963
3.2.3.stable [rel/stable] (commit #d2289a52)
go-algorand is licensed with AGPLv3.0
source code available at https://github.com/algorand/go-algorand

Indexer version
2.8.0-dev.unknown compiled at 2022-01-21T13:24:39+0000 from git hash cf2a3873600a95c5740f0a854ecd3e5636bb4afb (modified)

Postgres version
postgres (PostgreSQL) 13.4

[bbroder-algo]

when I run this test script with the address properly changed I also see the exception
algosdk.error.KMDHTTPError: {
"error": true,
"message": "could not decode request body"
}

[bbroder-algo]

I believe the behavior oysterpack is looking for is

import base64
bytes_data = base64.b32decode(address.encode('utf-8') + b'=' * 6)  
signed_txn = kmd_client.sign_transaction(handle=wallet_handle, password='', txn=txn, signing_address=base64.b64encode(bytes_data).decode())

which, if this is the case, should probably be performed by the sdk.

[oysterpack]

That hack works but is very ugly ... according to the SDK docs, a base32 encoded address should work

signing_address (str, optional): sign the transaction with SK corresponding to base32
        signing_address, if provided, rather than SK corresponding to sender

Thus, per the SDK docs, this is a bug.

[oysterpack]

Any updates on this?