src/EncryptedContentInfo.js

import * as asn1js from "asn1js";
import { getParametersValue, clearProps } from "pvutils";
import AlgorithmIdentifier from "./AlgorithmIdentifier.js";
//**************************************************************************************
/**
 * Class from RFC5652
 */
export default class EncryptedContentInfo
{
	//**********************************************************************************
	/**
	 * Constructor for EncryptedContentInfo class
	 * @param {Object} [parameters={}]
	 * @property {Object} [schema] asn1js parsed value
	 */
	constructor(parameters = {})
	{
		//region Internal properties of the object
		/**
		 * @type {string}
		 * @description contentType
		 */
		this.contentType = getParametersValue(parameters, "contentType", EncryptedContentInfo.defaultValues("contentType"));
		/**
		 * @type {AlgorithmIdentifier}
		 * @description contentEncryptionAlgorithm
		 */
		this.contentEncryptionAlgorithm = getParametersValue(parameters, "contentEncryptionAlgorithm", EncryptedContentInfo.defaultValues("contentEncryptionAlgorithm"));

		if("encryptedContent" in parameters)
		{
			/**
			 * @type {OctetString}
			 * @description encryptedContent (!!!) could be contructive or primitive value (!!!)
			 */
			this.encryptedContent = parameters.encryptedContent;
			
			if((this.encryptedContent.idBlock.tagClass === 1) &&
				(this.encryptedContent.idBlock.tagNumber === 4))
			{
				//region Divide OCTETSTRING value down to small pieces
				if(this.encryptedContent.idBlock.isConstructed === false)
				{
					const constrString = new asn1js.OctetString({
						idBlock: { isConstructed: true },
						isConstructed: true
					});
					
					let offset = 0;
					let length = this.encryptedContent.valueBlock.valueHex.byteLength;
					
					while(length > 0)
					{
						const pieceView = new Uint8Array(this.encryptedContent.valueBlock.valueHex, offset, ((offset + 1024) > this.encryptedContent.valueBlock.valueHex.byteLength) ? (this.encryptedContent.valueBlock.valueHex.byteLength - offset) : 1024);
						const _array = new ArrayBuffer(pieceView.length);
						const _view = new Uint8Array(_array);
						
						for(let i = 0; i < _view.length; i++)
							_view[i] = pieceView[i];
						
						constrString.valueBlock.value.push(new asn1js.OctetString({ valueHex: _array }));
						
						length -= pieceView.length;
						offset += pieceView.length;
					}
					
					this.encryptedContent = constrString;
				}
				//endregion
			}
		}
		//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 "contentType":
				return "";
			case "contentEncryptionAlgorithm":
				return new AlgorithmIdentifier();
			case "encryptedContent":
				return new asn1js.OctetString();
			default:
				throw new Error(`Invalid member name for EncryptedContentInfo 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 "contentType":
				return (memberValue === "");
			case "contentEncryptionAlgorithm":
				return ((memberValue.algorithmId === "") && (("algorithmParams" in memberValue) === false));
			case "encryptedContent":
				return (memberValue.isEqual(EncryptedContentInfo.defaultValues(memberName)));
			default:
				throw new Error(`Invalid member name for EncryptedContentInfo 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 = {})
	{
		//EncryptedContentInfo ::= SEQUENCE {
		//    contentType ContentType,
		//    contentEncryptionAlgorithm ContentEncryptionAlgorithmIdentifier,
		//    encryptedContent [0] IMPLICIT EncryptedContent OPTIONAL }
		//
		// Comment: Strange, but modern crypto engines create "encryptedContent" as "[0] EXPLICIT EncryptedContent"
		//
		//EncryptedContent ::= OCTET STRING

		/**
		 * @type {Object}
		 * @property {string} [blockName]
		 * @property {string} [contentType]
		 * @property {string} [contentEncryptionAlgorithm]
		 * @property {string} [encryptedContent]
		 */
		const names = getParametersValue(parameters, "names", {});

		return (new asn1js.Sequence({
			name: (names.blockName || ""),
			value: [
				new asn1js.ObjectIdentifier({ name: (names.contentType || "") }),
				AlgorithmIdentifier.schema(names.contentEncryptionAlgorithm || {}),
				// The CHOICE we need because "EncryptedContent" could have either "constructive"
				// or "primitive" form of encoding and we need to handle both variants
				new asn1js.Choice({
					value: [
						new asn1js.Constructed({
							name: (names.encryptedContent || ""),
							idBlock: {
								tagClass: 3, // CONTEXT-SPECIFIC
								tagNumber: 0 // [0]
							},
							value: [
								new asn1js.Repeated({
									value: new asn1js.OctetString()
								})
							]
						}),
						new asn1js.Primitive({
							name: (names.encryptedContent || ""),
							idBlock: {
								tagClass: 3, // CONTEXT-SPECIFIC
								tagNumber: 0 // [0]
							}
						})
					]
				})
			]
		}));
	}
	//**********************************************************************************
	/**
	 * Convert parsed asn1js object into current class
	 * @param {!Object} schema
	 */
	fromSchema(schema)
	{
		//region Clear input data first
		clearProps(schema, [
			"contentType",
			"contentEncryptionAlgorithm",
			"encryptedContent"
		]);
		//endregion
		
		//region Check the schema is valid
		const asn1 = asn1js.compareSchema(schema,
			schema,
			EncryptedContentInfo.schema({
				names: {
					contentType: "contentType",
					contentEncryptionAlgorithm: {
						names: {
							blockName: "contentEncryptionAlgorithm"
						}
					},
					encryptedContent: "encryptedContent"
				}
			})
		);

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

		//region Get internal properties from parsed schema
		this.contentType = asn1.result.contentType.valueBlock.toString();
		this.contentEncryptionAlgorithm = new AlgorithmIdentifier({ schema: asn1.result.contentEncryptionAlgorithm });

		if("encryptedContent" in asn1.result)
		{
			this.encryptedContent = asn1.result.encryptedContent;

			this.encryptedContent.idBlock.tagClass = 1; // UNIVERSAL
			this.encryptedContent.idBlock.tagNumber = 4; // OCTETSTRING (!!!) The value still has instance of "in_window.org.pkijs.asn1.ASN1_CONSTRUCTED / ASN1_PRIMITIVE"
		}
		//endregion
	}
	//**********************************************************************************
	/**
	 * Convert current object to asn1js object and set correct values
	 * @returns {Object} asn1js object
	 */
	toSchema()
	{
		//region Create array for output sequence
		const sequenceLengthBlock = {
			isIndefiniteForm: false
		};

		const outputArray = [];

		outputArray.push(new asn1js.ObjectIdentifier({ value: this.contentType }));
		outputArray.push(this.contentEncryptionAlgorithm.toSchema());

		if("encryptedContent" in this)
		{
			sequenceLengthBlock.isIndefiniteForm = this.encryptedContent.idBlock.isConstructed;

			const encryptedValue = this.encryptedContent;

			encryptedValue.idBlock.tagClass = 3; // CONTEXT-SPECIFIC
			encryptedValue.idBlock.tagNumber = 0; // [0]

			encryptedValue.lenBlock.isIndefiniteForm = this.encryptedContent.idBlock.isConstructed;

			outputArray.push(encryptedValue);
		}
		//endregion

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

		if("encryptedContent" in this)
			_object.encryptedContent = this.encryptedContent.toJSON();

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