aead-stream/dist/decrypt.js

Authenticated encryption on arbitrary large files

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.decrypt = void 0;
const chunkify_1 = require("./chunkify");
const crypto_1 = require("crypto");
const options_1 = require("./options");
async function* decrypt(key, ciphertext, options = options_1.defaultOptions) {
    const { algorithm, authTagLength, nonceLength, associatedData, chunkSize, } = options;
    let chunkIndex = 0;
    for await (const chunk of (0, chunkify_1.chunkify)(chunkSize, ciphertext)) {
        const nonce = chunk.slice(0, nonceLength);
        const authTag = chunk.slice(-authTagLength);
        let cipher = (0, crypto_1.createDecipheriv)(algorithm, key, nonce, {
            authTagLength,
        });
        let aad = Buffer.from([chunkIndex++]);
        if (associatedData) {
            aad = Buffer.concat([aad, associatedData]);
        }
        cipher.setAAD(aad, {
            plaintextLength: chunk.length,
        });
        cipher.setAuthTag(authTag);
        const plaintext = cipher.update(chunk.slice(nonceLength, chunk.length - authTagLength));
        cipher.final();
        yield plaintext;
    }
}
exports.decrypt = decrypt;