der-encode-test.js

var assert = require('assert');
var asn1 = require('..');
var BN = require('bn.js');

var Buffer = require('buffer').Buffer;

describe('asn1.js DER encoder', function() {
  /*
   * Explicit value shold be wrapped with A0 | EXPLICIT tag
   * this adds two more bytes to resulting buffer.
   * */
  it('should code explicit tag as 0xA2', function() {
    var E = asn1.define('E', function() {
      this.explicit(2).octstr()
    });

    var encoded = E.encode('X', 'der');

    // <Explicit tag> <wrapped len> <str tag> <len> <payload>
    assert.equal(encoded.toString('hex'), 'a203040158');
    assert.equal(encoded.length, 5);
  })

  function test(name, model_definition, model_value, der_expected) {
    it(name, function() {
      var Model, der_actual;
      Model = asn1.define('Model', model_definition);
      der_actual = Model.encode(model_value, 'der');
      assert.deepEqual(der_actual, new Buffer(der_expected,'hex'));
    });
  }

  test('should encode choice', function() {
    this.choice({
      apple: this.bool(),
    });
  }, { type: 'apple', value: true }, '0101ff');

  test('should encode implicit seqof', function() {
    var Int = asn1.define('Int', function() {
      this.int();
    });
    this.implicit(0).seqof(Int);
  }, [ 1 ], 'A003020101' );

  test('should encode explicit seqof', function() {
    var Int = asn1.define('Int', function() {
      this.int();
    });
    this.explicit(0).seqof(Int);
  }, [ 1 ], 'A0053003020101' );

  test('should encode BN(128) properly', function() {
    this.int();
  }, new BN(128), '02020080');

  test('should encode int 128 properly', function() {
    this.int();
  }, 128, '02020080');

  test('should encode 0x8011 properly', function() {
    this.int();
  }, 0x8011, '0203008011');

  test('should omit default value in DER', function() {
    this.seq().obj(
      this.key('required').def(false).bool(),
      this.key('value').int()
    );
  }, {required: false, value: 1}, '3003020101');
});