@bsv/sdk
Version:
BSV Blockchain Software Development Kit
97 lines • 4.61 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const BigNumber_js_1 = __importDefault(require("./BigNumber.js"));
const AESGCM_js_1 = require("./AESGCM.js");
const Random_js_1 = __importDefault(require("./Random.js"));
const utils_js_1 = require("./utils.js");
/**
* `SymmetricKey` is a class that extends the `BigNumber` class and implements symmetric encryption and decryption methods.
* Symmetric-Key encryption is a form of encryption where the same key is used to encrypt and decrypt the message.
* It leverages the Advanced Encryption Standard Galois/Counter Mode (AES-GCM) for encryption and decryption of messages.
*
* @class SymmetricKey
* @extends {BigNumber}
*/
class SymmetricKey extends BigNumber_js_1.default {
/**
* Generates a symmetric key randomly.
*
* @method fromRandom
* @static
* @returns The newly generated Symmetric Key.
*
* @example
* const symmetricKey = SymmetricKey.fromRandom();
*/
static fromRandom() {
return new SymmetricKey((0, Random_js_1.default)(32));
}
/**
* Encrypts a given message using AES-GCM encryption.
* The generated Initialization Vector (IV) is attached to the encrypted message for decryption purposes.
* The OpenSSL format of |IV|encryptedContent|authTag| is used.
*
* @method encrypt
* @param msg - The message to be encrypted. It can be a string or an array of numbers.
* @param enc - optional. The encoding of the message. If hex, the string is assumed to be hex, UTF-8 otherwise.
* @returns Returns the encrypted message as a string or an array of numbers, depending on `enc` argument.
*
* @example
* const key = new SymmetricKey(1234);
* const encryptedMessage = key.encrypt('plainText', 'utf8');
*/
encrypt(msg, enc) {
const iv = new Uint8Array((0, Random_js_1.default)(32));
const msgBytes = new Uint8Array((0, utils_js_1.toArray)(msg, enc));
const keyBytes = new Uint8Array(this.toArray('be', 32));
const { result, authenticationTag } = (0, AESGCM_js_1.AESGCM)(msgBytes, iv, keyBytes);
const totalLength = iv.length + result.length + authenticationTag.length;
const combined = new Uint8Array(totalLength);
let offset = 0;
combined.set(iv, offset);
offset += iv.length;
combined.set(result, offset);
offset += result.length;
combined.set(authenticationTag, offset);
return (0, utils_js_1.encode)(Array.from(combined), enc);
}
/**
* Decrypts a given AES-GCM encrypted message using the same key that was used for encryption.
* The method extracts the IV and the authentication tag from the encrypted message, then attempts to decrypt it.
* If the decryption fails (e.g., due to message tampering), an error is thrown.
*
* @method decrypt
* @param msg - The encrypted message to be decrypted. It can be a string or an array of numbers.
* @param enc - optional. The encoding of the message (if no encoding is provided, uses utf8 for strings, unless specified as hex).
* @returns Returns the decrypted message as a string or an array of numbers, depending on `enc` argument. If absent, an array of numbers is returned.
*
* @example
* const key = new SymmetricKey(1234);
* const decryptedMessage = key.decrypt(encryptedMessage, 'utf8');
*
* @throws {Error} Will throw an error if the decryption fails, likely due to message tampering or incorrect decryption key.
*/
decrypt(msg, enc) {
const msgBytes = new Uint8Array((0, utils_js_1.toArray)(msg, enc));
const ivLength = 32;
const tagLength = 16;
if (msgBytes.length < ivLength + tagLength) {
throw new Error('Ciphertext too short');
}
const iv = msgBytes.slice(0, ivLength);
const tagStart = msgBytes.length - tagLength;
const ciphertext = msgBytes.slice(ivLength, tagStart);
const messageTag = msgBytes.slice(tagStart);
const keyBytes = new Uint8Array(this.toArray('be', 32));
const result = (0, AESGCM_js_1.AESGCMDecrypt)(ciphertext, iv, messageTag, keyBytes);
if (result === null) {
throw new Error('Decryption failed!');
}
return (0, utils_js_1.encode)(Array.from(result), enc);
}
}
exports.default = SymmetricKey;
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