unable to deserialize protobuf bytes field in python

Question

I'm passing using protobuf an hashed byte array. but while trying to deserialize it, I'm getting the following error:

'utf-8' codec can't decode byte 0xd6 in position 1: 'utf-8' codec can't decode byte 0xd6 in position 1: invalid continuation byte in field: master.hash1

the code is simply:

a = message.ParseFromString(data)

I believe it is a simple matter of encoding\decoding, but I have no idea how to do so.

This is the code to encode the data in c#:

public byte[] HmacSign(string key, string message)
{
    var encoding = new System.Text.ASCIIEncoding();
    byte[] keyByte = encoding.GetBytes(key);

    HMACSHA1 hmacsha1 = new HMACSHA1(keyByte);

    byte[] messageBytes = encoding.GetBytes(message);
    byte[] hashmessage = hmacsha1.ComputeHash(messageBytes);

    return hashmessage;
}

Answer 1

You are using ASCII to encode your data so you have to use ASCII also to decode:

s = str(data, 'ascii')
message.ParseFromString(s)

If you prefer to use UTF-8, then change the encoding of your c# code:

public byte[] HmacSign(string key, string message)
{
    var encoding = new System.Text.UTF8Encoding();
    byte[] keyByte = encoding.GetBytes(key);

    HMACSHA1 hmacsha1 = new HMACSHA1(keyByte);

    byte[] messageBytes = encoding.GetBytes(message);

    byte[] hashmessage = hmacsha1.ComputeHash(messageBytes);
    return hashmessage;
}

And then use UTF-8 in your python code:

s = str(data, 'utf-8')
message.ParseFromString(s)

EDIT

If still not working, try to return a string from your c# code:

public string HmacSign(string key, string message)
{
    var encoding = new System.Text.UTF8Encoding();
    byte[] keyByte = encoding.GetBytes(key);
    byte[] messageBytes = encoding.GetBytes(message);
    using (var hmacsha new HMACSHA1(keyByte))
    {
        byte[] hashmessage = hmacsha.ComputeHash(messageBytes);
        return Convert.ToBase64String(hashmessage);
    }
}

And in your Python code:

import base64
s = base64.b64decode(data).decode('utf-8')
message.ParseFromString(s)