src/Signature.js

import * as asn1js from "asn1js";
import { getParametersValue, clearProps } from "pvutils";
import AlgorithmIdentifier from "./AlgorithmIdentifier.js";
import Certificate from "./Certificate.js";
//**************************************************************************************
/**
 * Class from RFC6960
 */
export default class Signature
{
	//**********************************************************************************
	/**
	 * Constructor for Signature class
	 * @param {Object} [parameters={}]
	 * @property {Object} [schema] asn1js parsed value
	 */
	constructor(parameters = {})
	{
		//region Internal properties of the object
		/**
		 * @type {AlgorithmIdentifier}
		 * @description signatureAlgorithm
		 */
		this.signatureAlgorithm = getParametersValue(parameters, "signatureAlgorithm", Signature.defaultValues("signatureAlgorithm"));
		/**
		 * @type {BitString}
		 * @description signature
		 */
		this.signature = getParametersValue(parameters, "signature", Signature.defaultValues("signature"));

		if("certs" in parameters)
			/**
			 * @type {Array.<Certificate>}
			 * @description certs
			 */
			this.certs = getParametersValue(parameters, "certs", Signature.defaultValues("certs"));
		//endregion

		//region If input argument array contains "schema" for this object
		if("schema" in parameters)
			this.fromSchema(parameters.schema);
		//endregion
	}
	//**********************************************************************************
	/**
	 * Return default values for all class members
	 * @param {string} memberName String name for a class member
	 */
	static defaultValues(memberName)
	{
		switch(memberName)
		{
			case "signatureAlgorithm":
				return new AlgorithmIdentifier();
			case "signature":
				return new asn1js.BitString();
			case "certs":
				return [];
			default:
				throw new Error(`Invalid member name for Signature class: ${memberName}`);
		}
	}
	//**********************************************************************************
	/**
	 * Compare values with default values for all class members
	 * @param {string} memberName String name for a class member
	 * @param {*} memberValue Value to compare with default value
	 */
	static compareWithDefault(memberName, memberValue)
	{
		switch(memberName)
		{
			case "signatureAlgorithm":
				return ((memberValue.algorithmId === "") && (("algorithmParams" in memberValue) === false));
			case "signature":
				return (memberValue.isEqual(Signature.defaultValues(memberName)));
			case "certs":
				return (memberValue.length === 0);
			default:
				throw new Error(`Invalid member name for Signature class: ${memberName}`);
		}
	}
	//**********************************************************************************
	/**
	 * Return value of asn1js schema for current class
	 * @param {Object} parameters Input parameters for the schema
	 * @returns {Object} asn1js schema object
	 */
	static schema(parameters = {})
	{
		//Signature       ::=     SEQUENCE {
		//    signatureAlgorithm      AlgorithmIdentifier,
		//    signature               BIT STRING,
		//    certs               [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL }

		/**
		 * @type {Object}
		 * @property {string} [blockName]
		 * @property {string} [signatureAlgorithm]
		 * @property {string} [signature]
		 * @property {string} [certs]
		 */
		const names = getParametersValue(parameters, "names", {});

		return (new asn1js.Sequence({
			name: (names.blockName || ""),
			value: [
				AlgorithmIdentifier.schema(names.signatureAlgorithm || {}),
				new asn1js.BitString({ name: (names.signature || "") }),
				new asn1js.Constructed({
					optional: true,
					idBlock: {
						tagClass: 3, // CONTEXT-SPECIFIC
						tagNumber: 0 // [0]
					},
					value: [
						new asn1js.Sequence({
							value: [new asn1js.Repeated({
								name: (names.certs || ""),
								value: Certificate.schema(names.certs || {})
							})]
						})
					]
				})
			]
		}));
	}
	//**********************************************************************************
	/**
	 * Convert parsed asn1js object into current class
	 * @param {!Object} schema
	 */
	fromSchema(schema)
	{
		//region Clear input data first
		clearProps(schema, [
			"signatureAlgorithm",
			"signature",
			"certs"
		]);
		//endregion
		
		//region Check the schema is valid
		const asn1 = asn1js.compareSchema(schema,
			schema,
			Signature.schema({
				names: {
					signatureAlgorithm: {
						names: {
							blockName: "signatureAlgorithm"
						}
					},
					signature: "signature",
					certs: "certs"
				}
			})
		);

		if(asn1.verified === false)
			throw new Error("Object's schema was not verified against input data for Signature");
		//endregion

		//region Get internal properties from parsed schema
		this.signatureAlgorithm = new AlgorithmIdentifier({ schema: asn1.result.signatureAlgorithm });
		this.signature = asn1.result.signature;

		if("certs" in asn1.result)
			this.certs = Array.from(asn1.result.certs, element => new Certificate({ schema: element }));
		//endregion
	}
	//**********************************************************************************
	/**
	 * Convert current object to asn1js object and set correct values
	 * @returns {Object} asn1js object
	 */
	toSchema()
	{
		//region Create array of output sequence
		const outputArray = [];

		outputArray.push(this.signatureAlgorithm.toSchema());
		outputArray.push(this.signature);

		if("certs" in this)
		{
			outputArray.push(new asn1js.Constructed({
				optional: true,
				idBlock: {
					tagClass: 3, // CONTEXT-SPECIFIC
					tagNumber: 0 // [0]
				},
				value: [
					new asn1js.Sequence({
						value: Array.from(this.certs, element => element.toSchema())
					})
				]
			}));
		}
		//endregion

		//region Construct and return new ASN.1 schema for this object
		return (new asn1js.Sequence({
			value: outputArray
		}));
		//endregion
	}
	//**********************************************************************************
	/**
	 * Convertion for the class to JSON object
	 * @returns {Object}
	 */
	toJSON()
	{
		const _object = {
			signatureAlgorithm: this.signatureAlgorithm.toJSON(),
			signature: this.signature.toJSON()
		};

		if("certs" in this)
			_object.certs = Array.from(this.certs, element => element.toJSON());

		return _object;
	}
	//**********************************************************************************
}
//**************************************************************************************