diff --git a/server/crates/arbiter-crypto/src/authn/v1.rs b/server/crates/arbiter-crypto/src/authn/v1.rs
index f192e76..5f21169 100644
--- a/server/crates/arbiter-crypto/src/authn/v1.rs
+++ b/server/crates/arbiter-crypto/src/authn/v1.rs
@@ -43,6 +43,14 @@ impl AuthChallenge {
             buffer
         }
     }
+
+    pub fn from_parts(nonce: &[u8], timestamp: i64) -> Result<Self, ()> {
+        let random_nonce = nonce.as_array().ok_or(())?;
+        Ok(AuthChallenge {
+            nonce: *random_nonce,
+            timestamp: DateTime::from_timestamp_nanos(timestamp),
+        })
+    }
 }
 
 pub type KeyParams = MlDsa87;
diff --git a/useragent/lib/features/connection/auth.dart b/useragent/lib/features/connection/auth.dart
index f7e50a8..84cb3d9 100644
--- a/useragent/lib/features/connection/auth.dart
+++ b/useragent/lib/features/connection/auth.dart
@@ -7,6 +7,7 @@ import 'package:arbiter/features/identity/pk_manager.dart';
 import 'package:arbiter/proto/arbiter.pbgrpc.dart';
 import 'package:arbiter/proto/user_agent/auth.pb.dart' as ua_auth;
 import 'package:arbiter/proto/user_agent.pb.dart';
+import 'package:arbiter/src/rust/api.dart';
 import 'package:grpc/grpc.dart';
 import 'package:mtcore/markettakers.dart';
 
@@ -92,7 +93,10 @@ Future<Connection> connectAndAuthorize(
       );
     }
 
-    final challenge = _formatChallenge(authResponse.challenge, pubkey);
+    final challenge = await formatChallenge(
+      random: authResponse.challenge.random,
+      timestamp: authResponse.challenge.timestampNanos.toInt(),
+    );
     talker.info(
       'Received auth challenge, signing with key ${base64Encode(pubkey)}',
     );
@@ -164,9 +168,3 @@ Future<Connection> _connect(StoredServerInfo serverInfo) async {
 
   return Connection(channel: channel, tx: tx, rx: rx);
 }
-
-List<int> _formatChallenge(ua_auth.AuthChallenge challenge, List<int> pubkey) {
-  final encodedPubkey = base64Encode(pubkey);
-  final payload = "${challenge.nonce}:$encodedPubkey";
-  return utf8.encode(payload);
-}
diff --git a/useragent/lib/proto/client/auth.pb.dart b/useragent/lib/proto/client/auth.pb.dart
index 98eaab1..ae19314 100644
--- a/useragent/lib/proto/client/auth.pb.dart
+++ b/useragent/lib/proto/client/auth.pb.dart
@@ -12,6 +12,7 @@
 
 import 'dart:core' as $core;
 
+import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;
 
 import '../shared/client.pb.dart' as $0;
@@ -94,12 +95,12 @@ class AuthChallengeRequest extends $pb.GeneratedMessage {
 
 class AuthChallenge extends $pb.GeneratedMessage {
   factory AuthChallenge({
-    $core.List<$core.int>? pubkey,
-    $core.int? nonce,
+    $fixnum.Int64? timestampNanos,
+    $core.List<$core.int>? random,
   }) {
     final result = create();
-    if (pubkey != null) result.pubkey = pubkey;
-    if (nonce != null) result.nonce = nonce;
+    if (timestampNanos != null) result.timestampNanos = timestampNanos;
+    if (random != null) result.random = random;
     return result;
   }
 
@@ -117,9 +118,11 @@ class AuthChallenge extends $pb.GeneratedMessage {
       package:
           const $pb.PackageName(_omitMessageNames ? '' : 'arbiter.client.auth'),
       createEmptyInstance: create)
+    ..a<$fixnum.Int64>(
+        1, _omitFieldNames ? '' : 'timestampNanos', $pb.PbFieldType.OU6,
+        defaultOrMaker: $fixnum.Int64.ZERO)
     ..a<$core.List<$core.int>>(
-        1, _omitFieldNames ? '' : 'pubkey', $pb.PbFieldType.OY)
-    ..aI(2, _omitFieldNames ? '' : 'nonce')
+        2, _omitFieldNames ? '' : 'random', $pb.PbFieldType.OY)
     ..hasRequiredFields = false;
 
   @$core.Deprecated('See https://github.com/google/protobuf.dart/issues/998.')
@@ -142,22 +145,22 @@ class AuthChallenge extends $pb.GeneratedMessage {
   static AuthChallenge? _defaultInstance;
 
   @$pb.TagNumber(1)
-  $core.List<$core.int> get pubkey => $_getN(0);
+  $fixnum.Int64 get timestampNanos => $_getI64(0);
   @$pb.TagNumber(1)
-  set pubkey($core.List<$core.int> value) => $_setBytes(0, value);
+  set timestampNanos($fixnum.Int64 value) => $_setInt64(0, value);
   @$pb.TagNumber(1)
-  $core.bool hasPubkey() => $_has(0);
+  $core.bool hasTimestampNanos() => $_has(0);
   @$pb.TagNumber(1)
-  void clearPubkey() => $_clearField(1);
+  void clearTimestampNanos() => $_clearField(1);
 
   @$pb.TagNumber(2)
-  $core.int get nonce => $_getIZ(1);
+  $core.List<$core.int> get random => $_getN(1);
   @$pb.TagNumber(2)
-  set nonce($core.int value) => $_setSignedInt32(1, value);
+  set random($core.List<$core.int> value) => $_setBytes(1, value);
   @$pb.TagNumber(2)
-  $core.bool hasNonce() => $_has(1);
+  $core.bool hasRandom() => $_has(1);
   @$pb.TagNumber(2)
-  void clearNonce() => $_clearField(2);
+  void clearRandom() => $_clearField(2);
 }
 
 class AuthChallengeSolution extends $pb.GeneratedMessage {
diff --git a/useragent/lib/proto/client/auth.pbjson.dart b/useragent/lib/proto/client/auth.pbjson.dart
index c9cf99e..c7b42b7 100644
--- a/useragent/lib/proto/client/auth.pbjson.dart
+++ b/useragent/lib/proto/client/auth.pbjson.dart
@@ -62,15 +62,15 @@ final $typed_data.Uint8List authChallengeRequestDescriptor = $convert.base64Deco
 const AuthChallenge$json = {
   '1': 'AuthChallenge',
   '2': [
-    {'1': 'pubkey', '3': 1, '4': 1, '5': 12, '10': 'pubkey'},
-    {'1': 'nonce', '3': 2, '4': 1, '5': 5, '10': 'nonce'},
+    {'1': 'timestamp_nanos', '3': 1, '4': 1, '5': 4, '10': 'timestampNanos'},
+    {'1': 'random', '3': 2, '4': 1, '5': 12, '10': 'random'},
   ],
 };
 
 /// Descriptor for `AuthChallenge`. Decode as a `google.protobuf.DescriptorProto`.
 final $typed_data.Uint8List authChallengeDescriptor = $convert.base64Decode(
-    'Cg1BdXRoQ2hhbGxlbmdlEhYKBnB1YmtleRgBIAEoDFIGcHVia2V5EhQKBW5vbmNlGAIgASgFUg'
-    'Vub25jZQ==');
+    'Cg1BdXRoQ2hhbGxlbmdlEicKD3RpbWVzdGFtcF9uYW5vcxgBIAEoBFIOdGltZXN0YW1wTmFub3'
+    'MSFgoGcmFuZG9tGAIgASgMUgZyYW5kb20=');
 
 @$core.Deprecated('Use authChallengeSolutionDescriptor instead')
 const AuthChallengeSolution$json = {
diff --git a/useragent/lib/proto/user_agent/auth.pb.dart b/useragent/lib/proto/user_agent/auth.pb.dart
index 1fa8bbd..c89b8c5 100644
--- a/useragent/lib/proto/user_agent/auth.pb.dart
+++ b/useragent/lib/proto/user_agent/auth.pb.dart
@@ -12,6 +12,7 @@
 
 import 'dart:core' as $core;
 
+import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;
 
 import 'auth.pbenum.dart';
@@ -90,10 +91,12 @@ class AuthChallengeRequest extends $pb.GeneratedMessage {
 
 class AuthChallenge extends $pb.GeneratedMessage {
   factory AuthChallenge({
-    $core.int? nonce,
+    $fixnum.Int64? timestampNanos,
+    $core.List<$core.int>? random,
   }) {
     final result = create();
-    if (nonce != null) result.nonce = nonce;
+    if (timestampNanos != null) result.timestampNanos = timestampNanos;
+    if (random != null) result.random = random;
     return result;
   }
 
@@ -111,7 +114,11 @@ class AuthChallenge extends $pb.GeneratedMessage {
       package: const $pb.PackageName(
           _omitMessageNames ? '' : 'arbiter.user_agent.auth'),
       createEmptyInstance: create)
-    ..aI(1, _omitFieldNames ? '' : 'nonce')
+    ..a<$fixnum.Int64>(
+        1, _omitFieldNames ? '' : 'timestampNanos', $pb.PbFieldType.OU6,
+        defaultOrMaker: $fixnum.Int64.ZERO)
+    ..a<$core.List<$core.int>>(
+        2, _omitFieldNames ? '' : 'random', $pb.PbFieldType.OY)
     ..hasRequiredFields = false;
 
   @$core.Deprecated('See https://github.com/google/protobuf.dart/issues/998.')
@@ -134,13 +141,22 @@ class AuthChallenge extends $pb.GeneratedMessage {
   static AuthChallenge? _defaultInstance;
 
   @$pb.TagNumber(1)
-  $core.int get nonce => $_getIZ(0);
+  $fixnum.Int64 get timestampNanos => $_getI64(0);
   @$pb.TagNumber(1)
-  set nonce($core.int value) => $_setSignedInt32(0, value);
+  set timestampNanos($fixnum.Int64 value) => $_setInt64(0, value);
   @$pb.TagNumber(1)
-  $core.bool hasNonce() => $_has(0);
+  $core.bool hasTimestampNanos() => $_has(0);
   @$pb.TagNumber(1)
-  void clearNonce() => $_clearField(1);
+  void clearTimestampNanos() => $_clearField(1);
+
+  @$pb.TagNumber(2)
+  $core.List<$core.int> get random => $_getN(1);
+  @$pb.TagNumber(2)
+  set random($core.List<$core.int> value) => $_setBytes(1, value);
+  @$pb.TagNumber(2)
+  $core.bool hasRandom() => $_has(1);
+  @$pb.TagNumber(2)
+  void clearRandom() => $_clearField(2);
 }
 
 class AuthChallengeSolution extends $pb.GeneratedMessage {
diff --git a/useragent/lib/proto/user_agent/auth.pbjson.dart b/useragent/lib/proto/user_agent/auth.pbjson.dart
index 7f7fe15..87d0979 100644
--- a/useragent/lib/proto/user_agent/auth.pbjson.dart
+++ b/useragent/lib/proto/user_agent/auth.pbjson.dart
@@ -67,13 +67,15 @@ final $typed_data.Uint8List authChallengeRequestDescriptor = $convert.base64Deco
 const AuthChallenge$json = {
   '1': 'AuthChallenge',
   '2': [
-    {'1': 'nonce', '3': 1, '4': 1, '5': 5, '10': 'nonce'},
+    {'1': 'timestamp_nanos', '3': 1, '4': 1, '5': 4, '10': 'timestampNanos'},
+    {'1': 'random', '3': 2, '4': 1, '5': 12, '10': 'random'},
   ],
 };
 
 /// Descriptor for `AuthChallenge`. Decode as a `google.protobuf.DescriptorProto`.
-final $typed_data.Uint8List authChallengeDescriptor = $convert
-    .base64Decode('Cg1BdXRoQ2hhbGxlbmdlEhQKBW5vbmNlGAEgASgFUgVub25jZQ==');
+final $typed_data.Uint8List authChallengeDescriptor = $convert.base64Decode(
+    'Cg1BdXRoQ2hhbGxlbmdlEicKD3RpbWVzdGFtcF9uYW5vcxgBIAEoBFIOdGltZXN0YW1wTmFub3'
+    'MSFgoGcmFuZG9tGAIgASgMUgZyYW5kb20=');
 
 @$core.Deprecated('Use authChallengeSolutionDescriptor instead')
 const AuthChallengeSolution$json = {
diff --git a/useragent/lib/src/rust/api.dart b/useragent/lib/src/rust/api.dart
index 0c22fbf..8648c0e 100644
--- a/useragent/lib/src/rust/api.dart
+++ b/useragent/lib/src/rust/api.dart
@@ -6,6 +6,14 @@
 import 'frb_generated.dart';
 import 'package:flutter_rust_bridge/flutter_rust_bridge_for_generated.dart';
 
+Future<Uint8List> formatChallenge({
+  required List<int> random,
+  required PlatformInt64 timestamp,
+}) => RustLib.instance.api.crateApiFormatChallenge(
+  random: random,
+  timestamp: timestamp,
+);
+
 // Rust type: RustOpaqueMoi<flutter_rust_bridge::for_generated::RustAutoOpaqueInner<MldsaKey>>
 abstract class MldsaKey implements RustOpaqueInterface {
   static Future<MldsaKey> fromBytes({required List<int> bytes}) =>
diff --git a/useragent/lib/src/rust/frb_generated.dart b/useragent/lib/src/rust/frb_generated.dart
index d9206e5..fa57ada 100644
--- a/useragent/lib/src/rust/frb_generated.dart
+++ b/useragent/lib/src/rust/frb_generated.dart
@@ -64,7 +64,7 @@ class RustLib extends BaseEntrypoint<RustLibApi, RustLibApiImpl, RustLibWire> {
   String get codegenVersion => '2.12.0';
 
   @override
-  int get rustContentHash => -437661335;
+  int get rustContentHash => 1247923898;
 
   static const kDefaultExternalLibraryLoaderConfig =
       ExternalLibraryLoaderConfig(
@@ -89,6 +89,11 @@ abstract class RustLibApi extends BaseApi {
 
   Future<Uint8List> crateApiMldsaKeyToBytes({required MldsaKey that});
 
+  Future<Uint8List> crateApiFormatChallenge({
+    required List<int> random,
+    required PlatformInt64 timestamp,
+  });
+
   RustArcIncrementStrongCountFnType
   get rust_arc_increment_strong_count_MldsaKey;
 
@@ -267,6 +272,40 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
   TaskConstMeta get kCrateApiMldsaKeyToBytesConstMeta =>
       const TaskConstMeta(debugName: "MldsaKey_to_bytes", argNames: ["that"]);
 
+  @override
+  Future<Uint8List> crateApiFormatChallenge({
+    required List<int> random,
+    required PlatformInt64 timestamp,
+  }) {
+    return handler.executeNormal(
+      NormalTask(
+        callFfi: (port_) {
+          final serializer = SseSerializer(generalizedFrbRustBinding);
+          sse_encode_list_prim_u_8_loose(random, serializer);
+          sse_encode_i_64(timestamp, serializer);
+          pdeCallFfi(
+            generalizedFrbRustBinding,
+            serializer,
+            funcId: 6,
+            port: port_,
+          );
+        },
+        codec: SseCodec(
+          decodeSuccessData: sse_decode_list_prim_u_8_strict,
+          decodeErrorData: sse_decode_String,
+        ),
+        constMeta: kCrateApiFormatChallengeConstMeta,
+        argValues: [random, timestamp],
+        apiImpl: this,
+      ),
+    );
+  }
+
+  TaskConstMeta get kCrateApiFormatChallengeConstMeta => const TaskConstMeta(
+    debugName: "format_challenge",
+    argNames: ["random", "timestamp"],
+  );
+
   RustArcIncrementStrongCountFnType
   get rust_arc_increment_strong_count_MldsaKey => wire
       .rust_arc_increment_strong_count_RustOpaque_flutter_rust_bridgefor_generatedRustAutoOpaqueInnerMldsaKey;
@@ -314,6 +353,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
     return raw as String;
   }
 
+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw) {
+    // Codec=Dco (DartCObject based), see doc to use other codecs
+    return dcoDecodeI64(raw);
+  }
+
   @protected
   List<int> dco_decode_list_prim_u_8_loose(dynamic raw) {
     // Codec=Dco (DartCObject based), see doc to use other codecs
@@ -394,6 +439,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
     return utf8.decoder.convert(inner);
   }
 
+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer) {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    return deserializer.buffer.getPlatformInt64();
+  }
+
   @protected
   List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer) {
     // Codec=Sse (Serialization based), see doc to use other codecs
@@ -491,6 +542,12 @@ class RustLibApiImpl extends RustLibApiImplPlatform implements RustLibApi {
     sse_encode_list_prim_u_8_strict(utf8.encoder.convert(self), serializer);
   }
 
+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer) {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    serializer.buffer.putPlatformInt64(self);
+  }
+
   @protected
   void sse_encode_list_prim_u_8_loose(
     List<int> self,
diff --git a/useragent/lib/src/rust/frb_generated.io.dart b/useragent/lib/src/rust/frb_generated.io.dart
index 942e9cd..3780c4e 100644
--- a/useragent/lib/src/rust/frb_generated.io.dart
+++ b/useragent/lib/src/rust/frb_generated.io.dart
@@ -46,6 +46,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   String dco_decode_String(dynamic raw);
 
+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw);
+
   @protected
   List<int> dco_decode_list_prim_u_8_loose(dynamic raw);
 
@@ -85,6 +88,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   String sse_decode_String(SseDeserializer deserializer);
 
+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer);
+
   @protected
   List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer);
 
@@ -136,6 +142,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   void sse_encode_String(String self, SseSerializer serializer);
 
+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer);
+
   @protected
   void sse_encode_list_prim_u_8_loose(List<int> self, SseSerializer serializer);
 
diff --git a/useragent/lib/src/rust/frb_generated.web.dart b/useragent/lib/src/rust/frb_generated.web.dart
index 640f1f8..e8a41cb 100644
--- a/useragent/lib/src/rust/frb_generated.web.dart
+++ b/useragent/lib/src/rust/frb_generated.web.dart
@@ -48,6 +48,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   String dco_decode_String(dynamic raw);
 
+  @protected
+  PlatformInt64 dco_decode_i_64(dynamic raw);
+
   @protected
   List<int> dco_decode_list_prim_u_8_loose(dynamic raw);
 
@@ -87,6 +90,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   String sse_decode_String(SseDeserializer deserializer);
 
+  @protected
+  PlatformInt64 sse_decode_i_64(SseDeserializer deserializer);
+
   @protected
   List<int> sse_decode_list_prim_u_8_loose(SseDeserializer deserializer);
 
@@ -138,6 +144,9 @@ abstract class RustLibApiImplPlatform extends BaseApiImpl<RustLibWire> {
   @protected
   void sse_encode_String(String self, SseSerializer serializer);
 
+  @protected
+  void sse_encode_i_64(PlatformInt64 self, SseSerializer serializer);
+
   @protected
   void sse_encode_list_prim_u_8_loose(List<int> self, SseSerializer serializer);
 
diff --git a/useragent/mise.toml b/useragent/mise.toml
new file mode 100644
index 0000000..540e6c5
--- /dev/null
+++ b/useragent/mise.toml
@@ -0,0 +1,4 @@
+[tasks.codegen]
+run = '''
+  flutter_rust_bridge_codegen generate 
+'''
diff --git a/useragent/rust/Cargo.lock b/useragent/rust/Cargo.lock
index 9b8db0c..5442523 100644
--- a/useragent/rust/Cargo.lock
+++ b/useragent/rust/Cargo.lock
@@ -232,7 +232,7 @@ checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 name = "arbiter-crypto"
 version = "0.1.0"
 dependencies = [
- "base64",
+ "chrono",
  "memsafe",
  "ml-dsa",
  "rand",
@@ -487,12 +487,6 @@ dependencies = [
  "rustc-demangle",
 ]
 
-[[package]]
-name = "base64"
-version = "0.22.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
-
 [[package]]
 name = "base64ct"
 version = "1.8.3"
@@ -718,6 +712,20 @@ dependencies = [
  "rand_core",
 ]
 
+[[package]]
+name = "chrono"
+version = "0.4.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c673075a2e0e5f4a1dde27ce9dee1ea4558c7ffe648f576438a20ca1d2acc4b0"
+dependencies = [
+ "iana-time-zone",
+ "js-sys",
+ "num-traits",
+ "serde",
+ "wasm-bindgen",
+ "windows-link",
+]
+
 [[package]]
 name = "clipboard-win"
 version = "5.4.1"
@@ -1821,6 +1829,30 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "iana-time-zone"
+version = "0.1.65"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e31bc9ad994ba00e440a8aa5c9ef0ec67d5cb5e5cb0cc7f8b744a35b389cc470"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "log",
+ "wasm-bindgen",
+ "windows-core",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "icu_collections"
 version = "2.2.0"
diff --git a/useragent/rust/src/api/mod.rs b/useragent/rust/src/api/mod.rs
index baaab3c..0590ab0 100644
--- a/useragent/rust/src/api/mod.rs
+++ b/useragent/rust/src/api/mod.rs
@@ -1,13 +1,15 @@
 use anyhow::anyhow;
+use arbiter_crypto::authn::{self, AuthChallenge, USERAGENT_CONTEXT};
 use flutter_rust_bridge::frb;
-use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};
 
 #[frb(opaque)]
 pub struct MldsaKey(authn::SigningKey);
 
 impl MldsaKey {
     pub fn from_bytes(bytes: &[u8]) -> anyhow::Result<Self> {
-        let bytes: [u8; 32] = bytes.try_into().map_err(|_| anyhow!("Invalid key length"))?;
+        let bytes: [u8; 32] = bytes
+            .try_into()
+            .map_err(|_| anyhow!("Invalid key length"))?;
         Ok(Self(authn::SigningKey::from_seed(bytes)))
     }
 
@@ -26,4 +28,11 @@ impl MldsaKey {
     pub fn get_public_key(&self) -> Vec<u8> {
         self.0.public_key().to_bytes().to_vec()
     }
-}
\ No newline at end of file
+}
+
+pub fn format_challenge(random: Vec<u8>, timestamp: i64) -> Result<Vec<u8>, String> {
+    let challenge = AuthChallenge::from_parts(&random, timestamp)
+        .map_err(|_| "Invalid nonce length".to_string())?;
+
+    Ok(challenge.format())
+}
diff --git a/useragent/rust/src/frb_generated.rs b/useragent/rust/src/frb_generated.rs
index 7489044..46647d0 100644
--- a/useragent/rust/src/frb_generated.rs
+++ b/useragent/rust/src/frb_generated.rs
@@ -39,7 +39,7 @@ flutter_rust_bridge::frb_generated_boilerplate!(
     default_rust_auto_opaque = RustAutoOpaqueMoi,
 );
 pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_VERSION: &str = "2.12.0";
-pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_CONTENT_HASH: i32 = -437661335;
+pub(crate) const FLUTTER_RUST_BRIDGE_CODEGEN_CONTENT_HASH: i32 = 1247923898;
 
 // Section: executor
 
@@ -267,6 +267,40 @@ fn wire__crate__api__MldsaKey_to_bytes_impl(
         },
     )
 }
+fn wire__crate__api__format_challenge_impl(
+    port_: flutter_rust_bridge::for_generated::MessagePort,
+    ptr_: flutter_rust_bridge::for_generated::PlatformGeneralizedUint8ListPtr,
+    rust_vec_len_: i32,
+    data_len_: i32,
+) {
+    FLUTTER_RUST_BRIDGE_HANDLER.wrap_normal::<flutter_rust_bridge::for_generated::SseCodec, _, _>(
+        flutter_rust_bridge::for_generated::TaskInfo {
+            debug_name: "format_challenge",
+            port: Some(port_),
+            mode: flutter_rust_bridge::for_generated::FfiCallMode::Normal,
+        },
+        move || {
+            let message = unsafe {
+                flutter_rust_bridge::for_generated::Dart2RustMessageSse::from_wire(
+                    ptr_,
+                    rust_vec_len_,
+                    data_len_,
+                )
+            };
+            let mut deserializer =
+                flutter_rust_bridge::for_generated::SseDeserializer::new(message);
+            let api_random = <Vec<u8>>::sse_decode(&mut deserializer);
+            let api_timestamp = <i64>::sse_decode(&mut deserializer);
+            deserializer.end();
+            move |context| {
+                transform_result_sse::<_, String>((move || {
+                    let output_ok = crate::api::format_challenge(api_random, api_timestamp)?;
+                    Ok(output_ok)
+                })())
+            }
+        },
+    )
+}
 
 // Section: related_funcs
 
@@ -312,6 +346,13 @@ impl SseDecode for String {
     }
 }
 
+impl SseDecode for i64 {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    fn sse_decode(deserializer: &mut flutter_rust_bridge::for_generated::SseDeserializer) -> Self {
+        deserializer.cursor.read_i64::<NativeEndian>().unwrap()
+    }
+}
+
 impl SseDecode for Vec<u8> {
     // Codec=Sse (Serialization based), see doc to use other codecs
     fn sse_decode(deserializer: &mut flutter_rust_bridge::for_generated::SseDeserializer) -> Self {
@@ -371,6 +412,7 @@ fn pde_ffi_dispatcher_primary_impl(
         3 => wire__crate__api__MldsaKey_get_public_key_impl(port, ptr, rust_vec_len, data_len),
         4 => wire__crate__api__MldsaKey_sign_impl(port, ptr, rust_vec_len, data_len),
         5 => wire__crate__api__MldsaKey_to_bytes_impl(port, ptr, rust_vec_len, data_len),
+        6 => wire__crate__api__format_challenge_impl(port, ptr, rust_vec_len, data_len),
         _ => unreachable!(),
     }
 }
@@ -436,6 +478,13 @@ impl SseEncode for String {
     }
 }
 
+impl SseEncode for i64 {
+    // Codec=Sse (Serialization based), see doc to use other codecs
+    fn sse_encode(self, serializer: &mut flutter_rust_bridge::for_generated::SseSerializer) {
+        serializer.cursor.write_i64::<NativeEndian>(self).unwrap();
+    }
+}
+
 impl SseEncode for Vec<u8> {
     // Codec=Sse (Serialization based), see doc to use other codecs
     fn sse_encode(self, serializer: &mut flutter_rust_bridge::for_generated::SseSerializer) {