cbor library

Validation of the CBOR subset that the cose and cwt libraries accept.

https://datatracker.ietf.org/doc/html/rfc8949

Encoding and decoding are left to the cbor package. The cose and cwt libraries encode plain Dart values with it and run verify on the result, so they only accept values that encode into this subset:

bool, null, int and String
Uint8List for byte strings, since any other List<int> encodes as an array of integers
Lists of supported values
Maps with integer keys, built in the deterministic order of RFC 8949 Section 4.2.1. Non-negative keys come first in ascending order, then negative keys as -1, -2, and so on

Floats, tags and indefinite lengths are rejected, so double, DateTime and Uri values cannot be used. A String holding a lone surrogate is rejected too, since it has no UTF-8 form.

import 'dart:typed_data';

import 'package:darkbio_crypto/cbor.dart' as cbor;

void example() {
  // [1, "two", h'03'] is within the subset
  cbor.verify(Uint8List.fromList([0x83, 0x01, 0x63, 0x74, 0x77, 0x6f, 0x41, 0x03]));

  // {2: 0, 1: 0} has its map keys out of order
  try {
    cbor.verify(Uint8List.fromList([0xa2, 0x02, 0x00, 0x01, 0x00]));
  } catch (err) {
    // Rejected, the error names the broken rule
  }
}

Functions

darkbio_crypto package

cbor library