Script to calculate KCV

Author: gcatanese

tools/hmac/README.md

@@ -32,3 +32,13 @@ npm list @adyen/api-library // check version of library and update if needed
 
 node calculateHmacPlatform.js 11223344D785FBAE710E7F943F307971BB61B21281C98C9129B3D4018A57B2EB payload2.json
 ```
+
+### Calculate KCV of the HMAC key
+
+Run `calculateKcv` passing the HMAC key:
+`node calculateKcv.js {hmacKey}`
+```
+cd tools/hmac
+
+node calculateKcv.js 00727DB817A85C8503AD29EAD1523DB869AF0E536893BB3046C92DE7CB045CB1
+```

tools/hmac/calculateKcv.js

@@ -0,0 +1,29 @@
+// script to calculate the KVC of the HMAC key
+//
+// Run with: `node calculateKcv.js {hmacKey} 
+//
+// cd tools/hmac
+// node calculateKcv.js 00727DB817A85C8503AD29EAD1523DB869AF0E536893BB3046C92DE7CB045CB1 should return 9540DA
+const crypto = require('crypto');
+
+// Ensure correct arguments
+if (process.argv.length !== 3) {
+    console.error("Usage: node calculateKcv.js <base64HmacKey>");
+    process.exit(1);
+}
+
+console.log(`Calculating KCV...`);
+
+const hmacKey = process.argv[2];
+// Convert the hex stringc
+const keyBuffer = Buffer.from(hmacKey, 'hex');
+
+const algorithm = 'sha256';
+
+const hmacSignature = crypto.createHmac(algorithm, keyBuffer).update("00000000").digest();
+
+// Take the last 3 bytes (6 hex characters) for the KCV
+const kcv = Buffer.from(hmacSignature.subarray(hmacSignature.length - 3)).toString('hex').toUpperCase();
+
+console.log('********');
+console.log(`KCV: ${kcv}`);