@peculiar/asn1-schema
This package uses ES2015 decorators to simplify working with ASN.1 creation and parsing.
Introduction
Abstract Syntax Notation One (ASN.1) is a standard interface description language for defining data structures that can be serialized and deserialized in a cross-platform way. Working with ASN.1 can be complicated as there are many ways to represent the same data and many solutions handcraft, incorrectly, the ASN.1 representation of the data.
asn1-schema
addresses this by using decorators to make both serialization and parsing of ASN.1 possible via a simple class that handles these problems for you.
This is important because validating input data before its use is important to do because all input data is evil.
Installation
Installation is handled via npm
:
$ npm install @peculiar/asn1-schema
TypeScript examples
Node.js:
ASN.1 schema
Extension ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
extnValue OCTET STRING
-- contains the DER encoding of an ASN.1 value
-- corresponding to the extension type identified
-- by extnID
}
id-ce-basicConstraints OBJECT IDENTIFIER ::= { id-ce 19 }
BasicConstraints ::= SEQUENCE {
cA BOOLEAN DEFAULT FALSE,
pathLenConstraint INTEGER (0..MAX) OPTIONAL
}
ASN.1 schema declaration in TypeScript project
import { Asn1Prop, Asn1PropTypes, Asn1Serializer } from "@peculiar/asn1-schema";
class Extension {
public static CRITICAL = false;
@AsnProp({ type: Asn1PropTypes.ObjectIdentifier })
public extnID: string = "";
@AsnProp({
type: Asn1PropTypes.Boolean,
defaultValue: Extension.CRITICAL,
})
public critical = Extension.CRITICAL;
@AsnProp({ type: Asn1PropTypes.OctetString })
public extnValue: ArrayBuffer = new ArrayBuffer(0);
}
class BasicConstraints {
@AsnProp({ type: Asn1PropTypes.Boolean, defaultValue: false })
public ca = false;
@AsnProp({ type: Asn1PropTypes.Integer, optional: true })
public pathLenConstraint?: number;
}
Encoding ASN.1 data
const basicConstraints = new BasicConstraints();
basicConstraints.ca = true;
basicConstraints.pathLenConstraint = 1;
const extension = new Extension();
extension.critical = true;
extension.extnID = "2.5.29.19";
extension.extnValue = AsnSerializer.serialize(basicConstraints);
console.log(Buffer.from(AsnSerializer.serialize(extension)).toString("hex"));
ASN.1 encoded data
Decoding ASN.1 data
const extension = AsnParser.parse(Buffer.from("30120603551d130101ff040830060101ff020101", "hex"), Extension);
console.log("Extension ID:", extension.extnID);
console.log("Critical:", extension.critical);
const basicConstraints = AsnParser.parse(extension.extnValue, BasicConstraints);
console.log("CA:", basicConstraints.ca);
console.log("Path length:", basicConstraints.pathLenConstraint);