How to use the asn1.Ber function in asn1

Crypto.prototype.ecdsaPrivateKeyToASN1 = function (prvKeyHex) {
        var Ber = require('asn1').Ber;
        var sk = new Ber.Writer();
        sk.startSequence();
        sk.writeInt(1);
        sk.writeBuffer(new Buffer(prvKeyHex, 'hex'), 4);
        sk.writeByte(160);
        sk.writeByte(7);
        if (this.securityLevel == CURVE_P_384_Size) {
            // OID of P384
            sk.writeOID('1.3.132.0.34');
        }
        else if (this.securityLevel == CURVE_P_256_Size) {
            // OID of P256
            sk.writeOID('1.2.840.10045.3.1.7');
        }
        else {
            throw Error("Not supported. Level " + this.securityLevel);

function readECDSACurve(der) {
	var curveName, curveNames;
	var j, c, cd;

	if (der.peek() === asn1.Ber.OID) {
		var oid = der.readOID();

		curveNames = Object.keys(algs.curves);
		for (j = 0; j < curveNames.length; ++j) {
			c = curveNames[j];
			cd = algs.curves[c];
			if (cd.pkcs8oid === oid) {
				curveName = c;
				break;
			}
		}

	} else {
		// ECParameters sequence
		der.readSequence();
		var version = der.readString(asn1.Ber.Integer, true);

// Curve sequence
		der.readSequence();
		curve.a = utils.mpNormalize(
		    der.readString(asn1.Ber.OctetString, true));
		curve.b = utils.mpNormalize(
		    der.readString(asn1.Ber.OctetString, true));
		if (der.peek() === asn1.Ber.BitString)
			curve.s = der.readString(asn1.Ber.BitString, true);

		// Combined Gx and Gy
		curve.G = der.readString(asn1.Ber.OctetString, true);
		assert.strictEqual(curve.G[0], 0x4,
		    'uncompressed G is required');

		curve.n = utils.mpNormalize(
		    der.readString(asn1.Ber.Integer, true));
		curve.h = utils.mpNormalize(
		    der.readString(asn1.Ber.Integer, true));
		assert.strictEqual(curve.h[0], 0x1, 'a cofactor=1 curve is ' +
		    'required');

		curveNames = Object.keys(algs.curves);
		var ks = Object.keys(curve);
		for (j = 0; j < curveNames.length; ++j) {
			c = curveNames[j];
			cd = algs.curves[c];
			var equal = true;
			for (var i = 0; i < ks.length; ++i) {
				var k = ks[i];
				if (cd[k] === undefined)
					continue;
				if (typeof (cd[k]) === 'object' &&

buf.writeString('ssh-' + this.type);
			buf.writePart(this.part.sig);
			return (buf.toBuffer());
		} else {
			return (this.part.sig.data);
		}

	case 'dsa':
	case 'ecdsa':
		var r, s;
		if (format === 'asn1') {
			var der = new asn1.BerWriter();
			der.startSequence();
			r = utils.mpNormalize(this.part.r.data);
			s = utils.mpNormalize(this.part.s.data);
			der.writeBuffer(r, asn1.Ber.Integer);
			der.writeBuffer(s, asn1.Ber.Integer);
			der.endSequence();
			return (der.buffer);
		} else if (format === 'ssh' && this.type === 'dsa') {
			buf = new SSHBuffer({});
			buf.writeString('ssh-dss');
			r = this.part.r.data;
			if (r.length > 20 && r[0] === 0x00)
				r = r.slice(1);
			s = this.part.s.data;
			if (s.length > 20 && s[0] === 0x00)
				s = s.slice(1);
			if ((this.hashAlgorithm &&
			    this.hashAlgorithm !== 'sha1') ||
			    r.length + s.length !== 40) {
				throw (new Error('OpenSSH only supports ' +

function Local(i) {
	return (asn1.Ber.Context | asn1.Ber.Constructor | i);
}

function writePkcs1DSAPrivate(der, key) {
	var ver = new Buffer(1);
	ver[0] = 0;
	der.writeBuffer(ver, asn1.Ber.Integer);

	der.writeBuffer(key.part.p.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.q.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.g.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.y.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.x.data, asn1.Ber.Integer);
}

Attribute.prototype.parse = function (ber) {
  assert.ok(ber);

  ber.readSequence();
  this.type = ber.readString();

  if (ber.peek() === Protocol.LBER_SET) {
    if (ber.readSequence(Protocol.LBER_SET)) {
      var end = ber.offset + ber.length;
      while (ber.offset < end)
        this._vals.push(ber.readString(asn1.Ber.OctetString, true));
    }
  }

  return true;
};

function writePkcs1DSAPrivate(der, key) {
	var ver = new Buffer(1);
	ver[0] = 0;
	der.writeBuffer(ver, asn1.Ber.Integer);

	der.writeBuffer(key.part.p.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.q.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.g.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.y.data, asn1.Ber.Integer);
	der.writeBuffer(key.part.x.data, asn1.Ber.Integer);
}

function Local(i) {
	return (asn1.Ber.Context | asn1.Ber.Constructor | i);
}

function readMPInt(der, nm) {
	assert.strictEqual(der.peek(), asn1.Ber.Integer,
	    nm + ' is not an Integer');
	return (utils.mpNormalize(der.readString(asn1.Ber.Integer, true)));
}