@cronstamp/clientlib/dist/certificate.js

Client library for cronstamp, a blockchain-based document timestamping and verification service.

import { hashString, isValidHash, VersionToHashAlgorithm } from './util/hash.js';
import { blockchainNames, blockchains } from './blockchains/blockchains.js';
import { ErrorTypes, ProcessError } from './lifecycle/manager.js';
export async function getCertificateFromFile(certificateFile) {
    let certificateString = await certificateFile.text();
    return getCertificateFromString(certificateString);
}
export async function getCertificateFromString(certificateString) {
    return JSON.parse(certificateString);
}
export class CertificateHelper {
    cert;
    constructor(cert) {
        this.cert = cert;
    }
    async calculateSaltedHash() {
        let flattenedBlockchains = this.cert.meta.blockchains.sort().join(',');
        let hashMetaContent = `${this.cert.meta.version}${flattenedBlockchains}${this.cert.meta.salt}`;
        let hashContent = this.cert.document_hash + hashMetaContent;
        return await hashString(hashContent, VersionToHashAlgorithm[this.cert.meta.version]);
    }
    /**
     * Check, if the blockchains array contains invalid or extra fields
     */
    static isValidBlockchainList(blockchains) {
        return blockchains ? blockchains.every((b) => blockchainNames.includes(b)) : false;
    }
    /**
     * Check if the certificate has all necessary data
     */
    hasData() {
        return (this.cert?.blockchains !== undefined &&
            this.cert.meta.version > 0 &&
            this.cert.meta.blockchains !== undefined &&
            this.cert.document_hash !== undefined &&
            this.cert.meta.salt !== undefined &&
            isValidHash(this.cert.document_hash, VersionToHashAlgorithm[this.cert.meta.version]));
    }
    //TODO: Use the abstract class for this
    getCertificateUnixTime() {
        let lastTimestamp = -1;
        for (const [name, data] of Object.entries(this.cert.blockchains)) {
            let blockchain = blockchains[name];
            if (data?.block_timestamp) {
                let timestamp = blockchain.getTransactionUnixTimestamp(data.block_timestamp);
                if (lastTimestamp < timestamp) {
                    lastTimestamp = timestamp;
                }
            }
        }
        if (lastTimestamp == -1) {
            throw new ProcessError('Unable to determine blockchain timestamp!', ErrorTypes.DOCUMENT_ALTERED);
        }
        return lastTimestamp;
    }
    getCertificateDate() {
        return new Date(this.getCertificateUnixTime());
    }
    getJSON() {
        return JSON.stringify(this.cert);
    }
}
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