src/ECPublicKey.js

import * as asn1js from "asn1js";
import { getParametersValue, utilConcatBuf, isEqualBuffer, toBase64, fromBase64, arrayBufferToString, stringToArrayBuffer } from "pvutils";
//**************************************************************************************
/**
 * Class from RFC5480
 */
export default class ECPublicKey
{
	//**********************************************************************************
	/**
	 * Constructor for ECCPublicKey class
	 * @param {Object} [parameters={}]
	 * @property {Object} [schema] asn1js parsed value
	 */
	constructor(parameters = {})
	{
		//region Internal properties of the object
		/**
		 * @type {ArrayBuffer}
		 * @description type
		 */
		this.x = getParametersValue(parameters, "x", ECPublicKey.defaultValues("x"));
		/**
		 * @type {ArrayBuffer}
		 * @description values
		 */
		this.y = getParametersValue(parameters, "y", ECPublicKey.defaultValues("y"));
		/**
		 * @type {string}
		 * @description namedCurve
		 */
		this.namedCurve = getParametersValue(parameters, "namedCurve", ECPublicKey.defaultValues("namedCurve"));
		//endregion

		//region If input argument array contains "schema" for this object
		if("schema" in parameters)
			this.fromSchema(parameters.schema);
		//endregion
		//region If input argument array contains "json" for this object
		if("json" in parameters)
			this.fromJSON(parameters.json);
		//endregion
	}
	//**********************************************************************************
	/**
	 * Return default values for all class members
	 * @param {string} memberName String name for a class member
	 */
	static defaultValues(memberName)
	{
		switch(memberName)
		{
			case "x":
			case "y":
				return new ArrayBuffer(0);
			case "namedCurve":
				return "";
			default:
				throw new Error(`Invalid member name for ECCPublicKey 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 "x":
			case "y":
				return (isEqualBuffer(memberValue, ECPublicKey.defaultValues(memberName)));
			case "namedCurve":
				return (memberValue === "");
			default:
				throw new Error(`Invalid member name for ECCPublicKey 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 = {})
	{
		return new asn1js.RawData();
	}
	//**********************************************************************************
	/**
	 * Convert ArrayBuffer into current class
	 * @param {!ArrayBuffer} schema Special case: schema is an ArrayBuffer
	 */
	fromSchema(schema)
	{
		//region Check the schema is valid
		if((schema instanceof ArrayBuffer) === false)
			throw new Error("Object's schema was not verified against input data for ECPublicKey");

		const view = new Uint8Array(schema);
		if(view[0] !== 0x04)
			throw new Error("Object's schema was not verified against input data for ECPublicKey");
		//endregion

		//region Get internal properties from parsed schema
		let coordinateLength;

		switch(this.namedCurve)
		{
			case "1.2.840.10045.3.1.7": // P-256
				coordinateLength = 32;
				break;
			case "1.3.132.0.34": // P-384
				coordinateLength = 48;
				break;
			case "1.3.132.0.35": // P-521
				coordinateLength = 66;
				break;
			default:
				throw new Error(`Incorrect curve OID: ${this.namedCurve}`);
		}

		if(schema.byteLength !== (coordinateLength * 2 + 1))
			throw new Error("Object's schema was not verified against input data for ECPublicKey");
		
		this.x = schema.slice(1, coordinateLength + 1);
		this.y = schema.slice(1 + coordinateLength, coordinateLength * 2 + 1);
		//endregion
	}
	//**********************************************************************************
	/**
	 * Convert current object to asn1js object and set correct values
	 * @returns {Object} asn1js object
	 */
	toSchema()
	{
		return new asn1js.RawData({ data: utilConcatBuf(
			(new Uint8Array([0x04])).buffer,
			this.x,
			this.y
		)
		});
	}
	//**********************************************************************************
	/**
	 * Convertion for the class to JSON object
	 * @returns {Object}
	 */
	toJSON()
	{
		let crvName = "";

		switch(this.namedCurve)
		{
			case "1.2.840.10045.3.1.7": // P-256
				crvName = "P-256";
				break;
			case "1.3.132.0.34": // P-384
				crvName = "P-384";
				break;
			case "1.3.132.0.35": // P-521
				crvName = "P-521";
				break;
			default:
		}

		return {
			crv: crvName,
			x: toBase64(arrayBufferToString(this.x), true, true, false),
			y: toBase64(arrayBufferToString(this.y), true, true, false)
		};
	}
	//**********************************************************************************
	/**
	 * Convert JSON value into current object
	 * @param {Object} json
	 */
	fromJSON(json)
	{
		let coodinateLength = 0;

		if("crv" in json)
		{
			switch(json.crv.toUpperCase())
			{
				case "P-256":
					this.namedCurve = "1.2.840.10045.3.1.7";
					coodinateLength = 32;
					break;
				case "P-384":
					this.namedCurve = "1.3.132.0.34";
					coodinateLength = 48;
					break;
				case "P-521":
					this.namedCurve = "1.3.132.0.35";
					coodinateLength = 66;
					break;
				default:
			}
		}
		else
			throw new Error("Absent mandatory parameter \"crv\"");

		if("x" in json)
		{
			const convertBuffer = stringToArrayBuffer(fromBase64(json.x, true));
			
			if(convertBuffer.byteLength < coodinateLength)
			{
				this.x = new ArrayBuffer(coodinateLength);
				const view = new Uint8Array(this.x);
				const convertBufferView = new Uint8Array(convertBuffer);
				view.set(convertBufferView, 1);
			}
			else
				this.x = convertBuffer.slice(0, coodinateLength);
		}
		else
			throw new Error("Absent mandatory parameter \"x\"");

		if("y" in json)
		{
			const convertBuffer = stringToArrayBuffer(fromBase64(json.y, true));
			
			if(convertBuffer.byteLength < coodinateLength)
			{
				this.y = new ArrayBuffer(coodinateLength);
				const view = new Uint8Array(this.y);
				const convertBufferView = new Uint8Array(convertBuffer);
				view.set(convertBufferView, 1);
			}
			else
				this.y = convertBuffer.slice(0, coodinateLength);
		}
		else
			throw new Error("Absent mandatory parameter \"y\"");
	}
	//**********************************************************************************
}
//**************************************************************************************