关于密钥格式的 CBOR 编码问题

Question

On javascript (not using node), I am facing different results when CBOR encoding using library ( https://github.com/paroga/cbor-js ) and when using CBOR online ( https://cbor.me/ ). Note that even using a more recent CBOR library, result is identical.

For instance setting an object such as:

const initial = { 1: "John", "-2": 456 };

Encoding using CBOR online gives: a201644a6f686e622d321901c8. Details are:

A2             # map(2)
   01          # unsigned(1)
   64          # text(4)
      4A6F686E # "John"
   62          # text(2)
      2D32     # "-2"
   19 01C8     # unsigned(456)

Now encoding using CBOR library on javascript gives a different result: a26131644a6f686e622d321901c8

When decoding this above Hexadecimal on CBOR online, I got: {"1": "John", "-2": 456}. Result is almost identical than the constant 'initial' except that key 1 now appears with a quote (").

CBOR online re-formats my hexadecimal value to a more 'readable' view:

A2             # map(2)
   61          # text(1)
      31       # "1"
   64          # text(4)
      4A6F686E # "John"
   62          # text(2)
      2D32     # "-2"
   19 01C8     # unsigned(456)

See below my Javascript code:

    //convert an array of bytes (as 8 bits) to string of Hex. ensure that Hex value are not return with 1 digit but 2 digits. ie '01' instead of '1'
    function toHexString(byteArray) {
      var s = '';
      byteArray.forEach(function(byte) {
        s += ('0' + (byte & 0xFF).toString(16)).slice(-2);
      });
      return s;
    }

    const initial = { 1: "John", "-2": 456 };
    
    var encoded = CBOR.encode(initial);
    var encodedHex = toHexString(Array.from(new Uint8Array(encoded)));
    console.log ( encodedHex );

I could manually replace specific hexadecimal values such as:

'61 31 64' replaced by '01 64'

But not fancy doing it as list could be important to cover all possible options.

Does someone have a workaround as I need my result to be 'a201644a6f686e622d321901c8' and not 'a26131644a6f686e622d321901c8'?

Answer 1

No workaround, but an attempt at explanation:

The CBOR specification, section 5.6 says:

In applications that need to interwork with JSON-based applications, conversion is simplified by limiting keys to text strings only

I assume the cbor-js package follows this approach and silently converts numeric keys to text keys.