Feature/aes gcm nodejs utility

utilities/aes-gcm-nodejs/.gitignore

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+node_modules/
+coverage/

utilities/aes-gcm-nodejs/README.md

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+# Crypto module in node.js
+
+**Note**: All examples here are shown in **base64** format. This can be changed in the constants.js file
+
+## Prerequisite
+
+Make sure you are in the root of folder (the folder which contains src, \_\_tests\_\_ and README.md) of the repo and have node installed (v16^).
+
+## Demo
+
+Run this command to run the script (A demo for key pair and shared key generation, encrpytion and decryption)
+
+```
+node src/index.js
+```
+
+Here is a sample output
+
+```
+Key Pair 1 ==>  {
+  publicKey: 'MCowBQYDK2VuAyEANyOBz6NyhiX4rrVyJpcekF0AUmE/aHPAO/b0bqY0EXw=',
+  privateKey: 'MC4CAQAwBQYDK2VuBCIEIPDHIoxb4nFan0TAxTBCJzbt1s+UNfVkKstth3AyG5By'
+}
+Key Pair 2 ==>  {
+  publicKey: 'MCowBQYDK2VuAyEAwScw6KPlklcKUufAtFJDjGmQ3cRMeQQVX2U0dpk7agI=',
+  privateKey: 'MC4CAQAwBQYDK2VuBCIEIDAZizDiwEPopeOPO63ajN6wrj65iXKNkpfmakHqQrF4'
+}
+SharedKey1 ==> X+T+C7UvJo258rAqAhT8NLRfh24/by+Vd6A1h9c3mno=
+SharedKey2 ==> X+T+C7UvJo258rAqAhT8NLRfh24/by+Vd6A1h9c3mno=
+sharedKey1 == sharedKey2 ==>  true
+Encrypted Data ===> eyJlbmNyeXB0ZWRfZGF0YSI6Ikk5L3hUVmNPTkZ1aVVBcm9PNHJwaG9hRnRKZFpyQ3NFRnR3SVJ3PT0iLCJobWFjIjoiUlNYOURWUXRGdk1DeTNVNTZyY2s0QT09Iiwibm9uY2UiOiJ2R01kU0VnRk9nVnAxalNnIn0=
+Decrypted Data ===> Hello This is ONDC Test Data
+```
+
+## Usage
+
+Functions in keyUtils.js and encryptionUtil.js can also be used individually (doc strings can be used as a guide)
+
+### keyUtil/generateKeyPair()
+
+Input: none
+
+Sample output:
+
+```
+{
+  publicKey: 'MCowBQYDK2VuAyEANyOBz6NyhiX4rrVyJpcekF0AUmE/aHPAO/b0bqY0EXw=',
+  privateKey: 'MC4CAQAwBQYDK2VuBCIEIPDHIoxb4nFan0TAxTBCJzbt1s+UNfVkKstth3AyG5By'
+}
+```
+
+### keyUtil/generateSharedKey(privateKeyString, publicKeyString)
+
+From keyPair1 and keyPair2, a shared key for both the parties is generated by using privateKey from one and publicKey from the other (Example: privateKey from keyPair1 and publicKey from keyPair2 or vise-versa)
+
+Input: privateKey (string), publicKey (string)
+
+Sample output:
+
+```
+X+T+C7UvJo258rAqAhT8NLRfh24/by+Vd6A1h9c3mno=
+```
+
+### encryptionUtil/encryptData(sharedKey, data)
+
+Input: sharedKey (string), data (string)
+
+Sample output:
+
+```
+eyJlbmNyeXB0ZWRfZGF0YSI6Ikk5L3hUVmNPTkZ1aVVBcm9PNHJwaG9hRnRKZFpyQ3NFRnR3SVJ3PT0iLCJobWFjIjoiUlNYOURWUXRGdk1DeTNVNTZyY2s0QT09Iiwibm9uY2UiOiJ2R01kU0VnRk9nVnAxalNnIn0=
+```
+
+**Note**: This encrypted string contains the information for decryption as well (hmac, nonce and encrypted string)
+
+### encryptionUtil/decryptData(sharedKey, eData)
+
+Input: sharedKey (string), encrypted data (string)
+
+Sample output:
+
+```
+Hello This is ONDC Test Data
+```
+
+**Note**: the shared key and encrypted data must be the same that was used for encrpytion.
+
+### encryptionUtil/convertPayloadToBase64(encryptedMessage, hmac, iv)
+
+Input: encrypted message (string), hmac (string), iv (string)
+
+Sample output:
+
+```
+eyJlbmNyeXB0ZWRfZGF0YSI6Ikk5L3hUVmNPTkZ1aVVBcm9PNHJwaG9hRnRKZFpyQ3NFRnR3SVJ3PT0iLCJobWFjIjoiUlNYOURWUXRGdk1DeTNVNTZyY2s0QT09Iiwibm9uY2UiOiJ2R01kU0VnRk9nVnAxalNnIn0=
+```
+
+## Tests and Coverage
+
+To get the code coverage, these are the following steps:
+
+1. Run this command to install testing libarary
+
+```
+npm install
+```
+
+2. Run this command to generate coverage report from test cases
+
+```
+npm run coverage
+```
+
+This should create a folder called `coverage`
+
+### Folder purpose
+
+index.js is the main flow (demo for generation of key pairs and shared key, encryption and decryption)
+
+keyUtil.js contains all the methods for creating key pairs and shared keys
+
+encryptionUtil.js contains all the logic for encryption and decryption
+
+constants.js contains all the variables that can be customised
+
+\_\_tests\_\_ contains all the test cases

utilities/aes-gcm-nodejs/__tests__/encryption.test.js

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+const { randomBytes } = require("crypto");
+const { encryptData, decryptData } = require("../src/encryptionUtil");
+
+test("Checking encryption with same shared key", () => {
+  const MESSAGE = "This is a secret...";
+  const sharedKey = randomBytes(32).toString("base64");
+
+  const encryptedData = encryptData(sharedKey, MESSAGE);
+  const decrpyedtData = decryptData(sharedKey, encryptedData);
+
+  expect(decrpyedtData === MESSAGE).toBe(true);
+});
+
+test("Checking encryption with different shared key", () => {
+  const MESSAGE = "This is a secret...";
+  const sharedKey1 = randomBytes(32).toString("base64");
+  const sharedKey2 = randomBytes(32).toString("base64");
+
+  const encryptedData = encryptData(sharedKey1, MESSAGE);
+  const decrpyedtData = decryptData(sharedKey2, encryptedData);
+
+  expect(decrpyedtData === MESSAGE).toBe(false);
+});

utilities/aes-gcm-nodejs/__tests__/sharedkey.test.js

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+const { generateKeyPair, generateSharedKey } = require("../src/keyUtil");
+
+test("Check if two pairs of keys generate the same shared key after exchange", () => {
+  const keyPair1 = generateKeyPair();
+  const keyPair2 = generateKeyPair();
+
+  const sharedKey1 = generateSharedKey(keyPair1.privateKey, keyPair2.publicKey);
+  const sharedKey2 = generateSharedKey(keyPair2.privateKey, keyPair1.publicKey);
+
+  expect(sharedKey1 === sharedKey2).toBe(true);
+});
+
+test("Check if two pairs of key generate the same shared key when not exchanged", () => {
+  const keyPair1 = generateKeyPair();
+  const keyPair2 = generateKeyPair();
+
+  const sharedKey1 = generateSharedKey(keyPair1.privateKey, keyPair1.publicKey);
+  const sharedKey2 = generateSharedKey(keyPair2.privateKey, keyPair2.publicKey);
+
+  expect(sharedKey1 === sharedKey2).toBe(false);
+});