How to use the crypt.SHA1 function in crypt

for (var i = 0; i < n; i++)
			x509[i] = Crypt.X509.decode(certs[i]);
		for (var i = 0; i < n - 1; i++) {
			var spki = x509[i + 1].spki;
			if (!this._verify(spki, x509[i]))
				return false;
		}
		var aki = Crypt.X509.decodeAKI(certs[n - 1]);
		if (aki) {
			var spki = this.findCert("ca.ski", aki);
			if (spki && this._verify(spki, x509[n - 1]))
				return true;
			// else fall thru
		}
		var tbs = Crypt.X509.decodeTBS(x509[n - 1].tbs);
		var sha1 = new Crypt.SHA1();
		var issuer = sha1.process(tbs.issuer);
		var spki = this.findCert("ca.subject", issuer);
		return spki && this._verify(spki, x509[n - 1]);
	};
	_verify(spki, x509) {

case SSL.cipherSuite.AES:
		var enc = new Crypt.AES(o.key);
		break;
	case SSL.cipherSuite.RC4:
		var enc = new Crypt.RC4(o.key);
		break;
	default:
		throw new Error("SSL: SetupCipher: unkown encryption algorithm");
	}
	switch (cipher.encryptionMode) {
	case SSL.cipherSuite.CBC:
	case SSL.cipherSuite.NONE:
		let h;
		switch (cipher.hashAlgorithm) {
		case SSL.cipherSuite.MD5: h = new Crypt.MD5(); break;
		case SSL.cipherSuite.SHA1: h = new Crypt.SHA1(); break;
		case SSL.cipherSuite.SHA256: h = new Crypt.SHA256(); break;
		case SSL.cipherSuite.SHA384: h = new Crypt.SHA384(); break;
		default:
			throw new Error("SSL: SetupCipher: unknown hash algorithm");
		}
		o.hmac = new Crypt.HMAC(h, o.macSecret);
		if (cipher.encryptionMode == SSL.cipherSuite.CBC)
			o.enc = new Crypt.CBC(enc, o.iv);	// no padding -- SSL 3.2 requires padding process beyond RFC2630
		else
			o.enc = enc;
		break;
	case SSL.cipherSuite.GCM:
		let Arith = require.weak("arith");
		o.enc = new Crypt.GCM(enc);
		o.nonce = new Arith.Integer(1);
		break;

*     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 */
import Crypt from "crypt";
import Arith from "arith";
import Files from "files";
import File from "file";
import Bin from "bin";

var argv = process.execArgv();
var f1 = new File("/k2/ca.ski", 1);
var f2 = new File("/k2/ca.subject", 1);
var sha1 = new Crypt.SHA1();
for (var argi = 1, argc = argv.length; argi < argc; argi++) {
	var crt = Files.read(argv[argi]);
	var ski = Crypt.X509.decodeSKI(crt);
	if (ski.byteLength > 20) {
		trace("SKI too long!\n");
		continue;
	}
	if (ski.byteLength < 20) {
		var buf = new Uint8Array(20);
		buf.fill(0);
		buf.set(new Uint8Array(ski), 20 - ski.byteLength);
		ski = buf.buffer;
	}
	f1.write(ski);
	console.log((new Arith.Integer(ski)).toString(16, 40));
	var x509 = Crypt.X509.decode(crt);

function PRF(session, secret, label, seed, n, hash)
{
	var s = ArrayBuffer.fromString(label);
	s = s.concat(seed);
	if (session.protocolVersion <= 0x302)
		var r = Bin.xor(
			p_hash(new Crypt.MD5(), secret.slice(0, iceil(secret.byteLength, 2)), s, n),
			p_hash(new Crypt.SHA1(), secret.slice(idiv(secret.byteLength, 2)), s, n)
		);
	else {
		if (!hash)
			hash = session.chosenCipher.hashAlgorithm == SSL.cipherSuite.SHA384 ? Crypt.SHA384 : Crypt.SHA256;
		var r = p_hash(new hash(), secret, s, n);
	}
	return r.slice(0, n);
}

constructor(key, priv, H, P, MGF) {
		this.rsa = new Crypt.RSA(priv ? key.privExponent: key.exponent, key.modulus, key.prim1, key.prim2, key.exponent1, key.exponent2, key.coefficient);
		this.modulusSize = this.rsa.modulusSize;
		this.H = H ? H: new Crypt.SHA1();
		this.P = P ? P: new Chunk();
		this.MGF = MGF ? MGF: this.MGF1SHA1;
	};
	static MGF1SHA1(Z, l) {

static MGF1SHA1(Z, l) {
		var H = new Crypt.SHA1();
		var hLen = H.outputSize;
		var T = new ArrayBuffer();
		for (var counter = 0; l > 0; counter++, l -= hLen) {
			var C = Crypt.PKCS1.sI2OSP(counter, 4);
			H.reset();
			H.update(Z, C);
			var bc = H.close();
			if (l < hLen)
				bc.length = l;
			T = T.concat(bc);
		}
		return(T);
	};
	xor(b1, b2) {