jose/dist/node/esm/runtime/asn1_sequence_decoder.js

Universal 'JSON Web Almost Everything' - JWA, JWS, JWE, JWT, JWK with no dependencies

const tagInteger = 0x02;
const tagSequence = 0x30;
export default class Asn1SequenceDecoder {
    constructor(buffer) {
        if (buffer[0] !== tagSequence) {
            throw new TypeError();
        }
        this.buffer = buffer;
        this.offset = 1;
        const len = this.decodeLength();
        if (len !== buffer.length - this.offset) {
            throw new TypeError();
        }
    }
    decodeLength() {
        let length = this.buffer[this.offset++];
        if (length & 0x80) {
            const nBytes = length & ~0x80;
            length = 0;
            for (let i = 0; i < nBytes; i++)
                length = (length << 8) | this.buffer[this.offset + i];
            this.offset += nBytes;
        }
        return length;
    }
    unsignedInteger() {
        if (this.buffer[this.offset++] !== tagInteger) {
            throw new TypeError();
        }
        let length = this.decodeLength();
        if (this.buffer[this.offset] === 0) {
            this.offset++;
            length--;
        }
        const result = this.buffer.slice(this.offset, this.offset + length);
        this.offset += length;
        return result;
    }
    end() {
        if (this.offset !== this.buffer.length) {
            throw new TypeError();
        }
    }
}