@bitblit/ratchet-common/lib/lang/simple-encryption-ratchet.js

Common tools for general use

import { RequireRatchet } from "./require-ratchet.js";
import { NumberRatchet } from "./number-ratchet.js";
import { Base64Ratchet } from "./base64-ratchet.js";
export class SimpleEncryptionRatchet {
    urlSafe;
    ivLength;
    sharedKey;
    constructor(sharedRawKey, urlSafe = false, ivLength = 12) {
        this.urlSafe = urlSafe;
        this.ivLength = ivLength;
        RequireRatchet.notNullOrUndefined(sharedRawKey);
        RequireRatchet.true(ivLength >= 12, 'ivLength must be at least 12');
        this.sharedKey = this.createSharedKey(sharedRawKey);
    }
    strToBuf(str) {
        return new TextEncoder().encode(str);
    }
    bufToBase64(buf) {
        return btoa(String.fromCharCode(...new Uint8Array(buf)));
    }
    base64ToBuf(base64) {
        return new Uint8Array(atob(base64).split('').map(c => c.charCodeAt(0)));
    }
    async encrypt(data) {
        const iv = crypto.getRandomValues(new Uint8Array(this.ivLength));
        const encoded = this.strToBuf(data);
        const key = await this.sharedKey;
        const ciphertext = await crypto.subtle.encrypt({ name: "AES-GCM", iv }, key, encoded);
        const ivMsg = this.bufToBase64(iv.buffer);
        const dataMsg = this.bufToBase64(ciphertext);
        let rval = ivMsg.length + 'K' + ivMsg + dataMsg;
        if (this.urlSafe) {
            rval = Base64Ratchet.encodeStringToBase64UrlString(rval);
        }
        return rval;
    }
    async decrypt(encryptedValueIn) {
        const encryptedValue = this.urlSafe ? Base64Ratchet.decodeBase64UrlStringToString(encryptedValueIn) : encryptedValueIn;
        const split = encryptedValue?.indexOf('K');
        if (!split || split < 1) {
            throw new Error('Invalid split : ' + split);
        }
        const ivLen = NumberRatchet.safeNumber(encryptedValue.substring(0, split));
        const iv = encryptedValue.substring(split + 1, split + 1 + ivLen);
        const data = encryptedValue.substring(split + 1 + ivLen);
        const key = await this.sharedKey;
        const decrypted = await crypto.subtle.decrypt({ name: "AES-GCM", iv: this.base64ToBuf(iv) }, key, this.base64ToBuf(data));
        return new TextDecoder().decode(decrypted);
    }
    async createSharedKey(rawKeyIn) {
        const rawKey = typeof rawKeyIn === 'string' ? rawKeyIn : await rawKeyIn;
        const keyMaterial = this.strToBuf(rawKey.padEnd(32, '0').slice(0, 32));
        return crypto.subtle.importKey("raw", keyMaterial, "AES-GCM", false, ["encrypt", "decrypt"]);
    }
}
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