diff --git a/examples/parse.ts b/examples/parse.ts
new file mode 100644
index 0000000..32bff62
--- /dev/null
+++ b/examples/parse.ts
@@ -0,0 +1,18 @@
+import { CAT } from '../src';
+
+async function main() {
+  const parser = new CAT({
+    keys: {
+      Symmetric256: Buffer.from(
+        '403697de87af64611c1d32a05dab0fe1fcb715a86ab435f1ec99192d79569388',
+        'hex'
+      )
+    }
+  });
+  const result = await parser.validate(process.argv[2], 'mac', {
+    issuer: 'eyevinn'
+  });
+  console.log(result);
+}
+
+main();
diff --git a/src/cat.ts b/src/cat.ts
index f8fb5f8..b131489 100644
--- a/src/cat.ts
+++ b/src/cat.ts
@@ -15,6 +15,7 @@ import { CommonAccessTokenUri } from './catu';
 import { CommonAccessTokenRenewal } from './catr';
 import { CommonAccessTokenHeader } from './cath';
 import { CommonAccessTokenIf } from './catif';
+import { toBase64, toHex } from './util';
 
 export const claimsToLabels: { [key: string]: number } = {
   iss: 1, // 3
@@ -76,8 +77,8 @@ const claimTransform: { [key: string]: (value: string) => Buffer } = {
 };
 
 const claimTransformReverse: { [key: string]: (value: Buffer) => string } = {
-  cti: (value: Buffer) => value.toString('hex'),
-  cattpk: (value: Buffer) => value.toString('hex')
+  cti: (value: Buffer) => toHex(value),
+  cattpk: (value: Buffer) => toHex(value)
 };
 
 const claimTypeValidators: {
@@ -492,7 +493,7 @@ export class CommonAccessToken {
   }
 
   get base64() {
-    return this.data?.toString('base64');
+    return this.data ? toBase64(this.data) : undefined;
   }
 
   get keyId() {
diff --git a/src/index.ts b/src/index.ts
index b6ec269..af1eaea 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,7 @@ import {
   CommonAccessTokenFactory
 } from './cat';
 import { KeyNotFoundError } from './errors';
+import { generateRandomHex, toBase64 } from './util';
 
 export { CommonAccessToken } from './cat';
 export { CommonAccessTokenRenewal } from './catr';
@@ -225,7 +226,7 @@ export class CAT {
     opts?: CatGenerateOptions
   ) {
     if (opts?.generateCwtId) {
-      claims['cti'] = crypto.randomBytes(16).toString('hex');
+      claims['cti'] = generateRandomHex(16);
     }
     const cat = new CommonAccessToken(claims);
     if (opts && opts.type == 'mac') {
@@ -239,7 +240,7 @@ export class CAT {
       if (!cat.raw) {
         throw new Error('Failed to MAC token');
       }
-      return cat.raw.toString('base64');
+      return toBase64(cat.raw);
     }
   }
 
@@ -281,7 +282,7 @@ export class CAT {
     opts?: CatGenerateOptions
   ) {
     if (opts?.generateCwtId) {
-      dict['cti'] = crypto.randomBytes(16).toString('hex');
+      dict['cti'] = generateRandomHex(16);
     }
     const cat = CommonAccessTokenFactory.fromDict(dict);
     if (opts && opts.type == 'mac') {
@@ -295,7 +296,7 @@ export class CAT {
       if (!cat.raw) {
         throw new Error('Failed to MAC token');
       }
-      return cat.raw.toString('base64');
+      return toBase64(cat.raw);
     }
   }
 
@@ -313,7 +314,7 @@ export class CAT {
     opts: CatRenewOptions
   ): Promise<string> {
     const newClaims = cat.claims;
-    newClaims['cti'] = crypto.randomBytes(16).toString('hex');
+    newClaims['cti'] = generateRandomHex(16);
     newClaims['iat'] = Math.floor(Date.now() / 1000);
     newClaims['iss'] = opts.issuer;
     newClaims['exp'] = newClaims['iat'] + (newClaims['catr'] as any)['expadd'];
@@ -329,6 +330,6 @@ export class CAT {
     if (!newCat.raw) {
       throw new Error('Failed to MAC token');
     }
-    return newCat.raw.toString('base64');
+    return toBase64(newCat.raw);
   }
 }
diff --git a/src/util.ts b/src/util.ts
new file mode 100644
index 0000000..202e242
--- /dev/null
+++ b/src/util.ts
@@ -0,0 +1,26 @@
+import crypto from 'crypto';
+
+/**
+ * Generate a random hex string of specified length
+ * @param bytes Number of random bytes to generate
+ * @returns Hex string
+ */
+export function generateRandomHex(bytes: number): string {
+  const randomBytes = new Uint8Array(bytes);
+  crypto.getRandomValues(randomBytes);
+  return Array.from(randomBytes)
+    .map((byte) => byte.toString(16).padStart(2, '0'))
+    .join('');
+}
+
+export function toBase64(input: Buffer): string {
+  const bytes = new Uint8Array(input);
+  return btoa(String.fromCharCode(...bytes));
+}
+
+export function toHex(input: Buffer): string {
+  const bytes = new Uint8Array(input);
+  return Array.from(bytes)
+    .map((byte) => byte.toString(16).padStart(2, '0'))
+    .join('');
+}