diff --git a/package.json b/package.json
index d499514d..06308103 100644
--- a/package.json
+++ b/package.json
@@ -7,6 +7,7 @@
     "@formkit/auto-animate": "^0.7.0",
     "@headlessui/react": "^1.5.0",
     "@movie-web/providers": "^1.0.4",
+    "@noble/hashes": "^1.3.2",
     "@react-spring/web": "^9.7.1",
     "@scure/bip39": "^1.2.1",
     "@sozialhelden/ietf-language-tags": "^5.4.2",
@@ -33,7 +34,6 @@
     "react-use": "^17.4.0",
     "slugify": "^1.6.6",
     "subsrt-ts": "^2.1.1",
-    "universal-base64url": "^1.1.0",
     "unzipit": "^1.4.3",
     "zustand": "^4.3.9"
   },
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 94e4a7eb..e84a4c83 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -20,6 +20,9 @@ dependencies:
   '@movie-web/providers':
     specifier: ^1.0.4
     version: 1.0.4
+  '@noble/hashes':
+    specifier: ^1.3.2
+    version: 1.3.2
   '@react-spring/web':
     specifier: ^9.7.1
     version: 9.7.3(react-dom@17.0.2)(react@17.0.2)
@@ -98,9 +101,6 @@ dependencies:
   subsrt-ts:
     specifier: ^2.1.1
     version: 2.1.1
-  universal-base64url:
-    specifier: ^1.1.0
-    version: 1.1.0
   unzipit:
     specifier: ^1.4.3
     version: 1.4.3
@@ -6150,16 +6150,6 @@ packages:
       crypto-random-string: 2.0.0
     dev: true
 
-  /universal-base64@2.1.0:
-    resolution: {integrity: sha512-WeOkACVnIXJZr/qlv7++Rl1zuZOHN96v2yS5oleUuv8eJOs5j9M5U3xQEIoWqn1OzIuIcgw0fswxWnUVGDfW6g==}
-    dev: false
-
-  /universal-base64url@1.1.0:
-    resolution: {integrity: sha512-qWv2+8KCaAWdpqqXwU8W0Yj9pflYDXP37/a3kec6Y4Je7bYzgIfxEVRjZWeLR67be7iot1lGCy5Nuo+xB0fojA==}
-    dependencies:
-      universal-base64: 2.1.0
-    dev: false
-
   /universalify@0.2.0:
     resolution: {integrity: sha512-CJ1QgKmNg3CwvAv/kOFmtnEN05f0D/cn9QntgNOQlQF9dgvVTHj3t+8JPdjqawCHk7V/KA+fbUqzZ9XWhcqPUg==}
     engines: {node: '>= 4.0.0'}
diff --git a/src/backend/accounts/crypto.ts b/src/backend/accounts/crypto.ts
index 8ab25163..31642199 100644
--- a/src/backend/accounts/crypto.ts
+++ b/src/backend/accounts/crypto.ts
@@ -1,13 +1,14 @@
+import { pbkdf2Async } from "@noble/hashes/pbkdf2";
+import { sha256 } from "@noble/hashes/sha256";
 import { generateMnemonic } from "@scure/bip39";
 import { wordlist } from "@scure/bip39/wordlists/english";
 import forge from "node-forge";
-import { encode } from "universal-base64url";
 
 async function seedFromMnemonic(mnemonic: string) {
-  const md = forge.md.sha256.create();
-  md.update(mnemonic);
-  // TODO this is probably not correct
-  return md.digest().toHex();
+  return pbkdf2Async(sha256, mnemonic, "mnemonic", {
+    c: 2048,
+    dkLen: 32,
+  });
 }
 
 export async function keysFromMenmonic(mnemonic: string) {
@@ -28,13 +29,19 @@ export function genMnemonic(): string {
 }
 
 export async function signCode(
-  _code: string,
-  _privateKey: forge.pki.ed25519.NativeBuffer
-): Promise<Uint8Array> {
-  // TODO add real signature
-  return new Uint8Array();
+  code: string,
+  privateKey: forge.pki.ed25519.NativeBuffer
+): Promise<forge.pki.ed25519.NativeBuffer> {
+  return forge.pki.ed25519.sign({
+    encoding: "utf8",
+    message: code,
+    privateKey,
+  });
 }
 
 export function bytesToBase64Url(bytes: Uint8Array): string {
-  return encode(String.fromCodePoint(...bytes));
+  return btoa(String.fromCodePoint(...bytes))
+    .replace(/\//g, "_")
+    .replace(/\+/g, "-")
+    .replace(/=+$/, "");
 }
diff --git a/src/backend/accounts/register.ts b/src/backend/accounts/register.ts
index 93f2794d..507d4cf9 100644
--- a/src/backend/accounts/register.ts
+++ b/src/backend/accounts/register.ts
@@ -1,7 +1,11 @@
 import { ofetch } from "ofetch";
 
 import { SessionResponse, UserResponse } from "@/backend/accounts/auth";
-import { keysFromMenmonic, signCode } from "@/backend/accounts/crypto";
+import {
+  bytesToBase64Url,
+  keysFromMenmonic as keysFromMnemonic,
+  signCode,
+} from "@/backend/accounts/crypto";
 
 export interface ChallengeTokenResponse {
   challenge: string;
@@ -55,10 +59,10 @@ export async function registerAccount(
 }
 
 export async function signChallenge(mnemonic: string, challengeCode: string) {
-  const keys = await keysFromMenmonic(mnemonic);
+  const keys = await keysFromMnemonic(mnemonic);
   const signature = await signCode(challengeCode, keys.privateKey);
   return {
-    publicKey: keys.publicKey,
-    signature,
+    publicKey: bytesToBase64Url(keys.publicKey),
+    signature: bytesToBase64Url(signature),
   };
 }
diff --git a/src/pages/parts/auth/VerifyPassphrasePart.tsx b/src/pages/parts/auth/VerifyPassphrasePart.tsx
index 9b5b2222..8d7f5698 100644
--- a/src/pages/parts/auth/VerifyPassphrasePart.tsx
+++ b/src/pages/parts/auth/VerifyPassphrasePart.tsx
@@ -1,7 +1,6 @@
 import { useState } from "react";
 import { useAsyncFn } from "react-use";
 
-import { bytesToBase64Url } from "@/backend/accounts/crypto";
 import {
   getRegisterChallengeToken,
   registerAccount,
@@ -37,9 +36,9 @@ export function VerifyPassphrase(props: VerifyPassphraseProps) {
       const registerResult = await registerAccount(url, {
         challenge: {
           code: challenge,
-          signature: bytesToBase64Url(keys.signature),
+          signature: keys.signature,
         },
-        publicKey: bytesToBase64Url(keys.publicKey),
+        publicKey: keys.publicKey,
         device: props.profile.device,
         profile: props.profile.profile,
       });