feat: move buildStorageKeySuffix function to common and bump release (#207)

* move  function to common and bump release
* hash the API key for added obscurity
* lint

Author: typotter

src/index.ts

@@ -64,6 +64,7 @@ import {
   Variation,
   Environment,
 } from './interfaces';
+import { buildStorageKeySuffix } from './obfuscation';
 import {
   AttributeType,
   Attributes,
@@ -155,4 +156,7 @@ export {
 
   // Test helpers
   decodePrecomputedFlag,
+
+  // Utilities
+  buildStorageKeySuffix,
 };

src/obfuscation.spec.ts

@@ -1,5 +1,10 @@
 import { IPrecomputedBandit } from './interfaces';
-import { decodeBase64, encodeBase64, obfuscatePrecomputedBanditMap } from './obfuscation';
+import {
+  buildStorageKeySuffix,
+  decodeBase64,
+  encodeBase64,
+  obfuscatePrecomputedBanditMap,
+} from './obfuscation';
 
 describe('obfuscation', () => {
   it('encodes strings to base64', () => {
@@ -10,6 +15,14 @@ describe('obfuscation', () => {
     expect(decodeBase64('NS4w')).toEqual('5.0');
   });
 
+  it('hashes API keys for storage key suffixes', () => {
+    expect(buildStorageKeySuffix('MYKEY')).toEqual('ea89bd7e7594e5be');
+    expect(buildStorageKeySuffix('MYKEY2')).toEqual('3fc4c6f1358c630f');
+    expect(buildStorageKeySuffix('fwezo8v7nsotfizw3rtw===.3t wtw4ztwe3tjw8')).toEqual(
+      'cf6c7dcee0987554',
+    );
+  });
+
   it('encodes/decodes regex', () => {
     const regexes = ['.*@example.com', '.*@.*.com$', 'hello world'];
 

src/obfuscation.ts

@@ -8,6 +8,18 @@ export function getMD5Hash(input: string, salt = ''): string {
   return new SparkMD5().append(salt).append(input).end();
 }
 
+/**
+ * Builds a storage key suffix from an API key.
+ * @param apiKey - The API key to build the suffix from
+ * @returns A string suffix for storage keys
+ * @public
+ */
+export function buildStorageKeySuffix(apiKey: string): string {
+  // Note that we hash the API key and use the first 16 characters of the digest.
+  const hashed = getMD5Hash(apiKey);
+  return hashed.slice(0, 16);
+}
+
 export function encodeBase64(input: string) {
   return base64.encode(input);
 }