feat: implements GenerateAuthorizationSignature support on PrivyUser

SDK/Runtime/Auth/Models/IPrivyUser.cs

@@ -89,5 +89,29 @@ public interface IPrivyUser
         /// Creates a new Solana embedded wallet for the user.
         /// </summary>
         Task<IEmbeddedSolanaWallet> CreateSolanaWallet(bool allowAdditional = false);
+
+        /// <summary>
+        /// Generates a cryptographic signature for an API request payload using the
+        /// authenticated user's signing key.
+        ///
+        /// This method canonicalizes the payload to JSON (RFC 8785) and signs the
+        /// canonical bytes. The returned base64-encoded signature can be included as
+        /// the <c>privy-authorization-signature</c> header to authorize Privy API requests.
+        /// </summary>
+        /// <param name="payload">The <see cref="WalletApiPayload"/> containing the API request details to be signed.</param>
+        /// <returns>A task whose result is the base64-encoded signature string.</returns>
+        Task<string> GenerateAuthorizationSignature(WalletApiPayload payload);
+
+        /// <summary>
+        /// Generates a cryptographic signature for a pre-serialized binary payload using the
+        /// authenticated user's signing key.
+        ///
+        /// Unlike the typed payload variant, this method skips JSON canonicalization and signs the
+        /// raw bytes directly. Use this when you have already serialized and canonicalized your
+        /// payload outside the SDK.
+        /// </summary>
+        /// <param name="payload">The pre-serialized payload bytes to sign.</param>
+        /// <returns>A task whose result is the base64-encoded signature string.</returns>
+        Task<string> GenerateAuthorizationSignature(byte[] payload);
     }
 }

SDK/Runtime/Auth/Models/PrivyUser.cs

@@ -98,20 +98,22 @@ public Dictionary<string, string> CustomMetadata
         private AppConfigRepository _appConfigRepository;
         private WalletApiWalletCreator _walletApiWalletCreator;
         private WalletApiRepository _walletApiRepository;
+        private IAuthorizationKey _authorizationKey;
 
         private EmbeddedWalletManager _embeddedWalletManager;
 
         //Constructor is internal, but the object is public facing
         //TODO: Create Interface class for this
         internal PrivyUser(AuthDelegator authDelegator, EmbeddedWalletManager embeddedWalletManager,
             AppConfigRepository appConfigRepository, WalletApiWalletCreator walletApiWalletCreator,
-            WalletApiRepository walletApiRepository)
+            WalletApiRepository walletApiRepository, IAuthorizationKey authorizationKey)
         {
             _authDelegator = authDelegator;
             _embeddedWalletManager = embeddedWalletManager;
             _appConfigRepository = appConfigRepository;
             _walletApiWalletCreator = walletApiWalletCreator;
             _walletApiRepository = walletApiRepository;
+            _authorizationKey = authorizationKey;
         }
 
         public async Task<string> GetAccessToken()
@@ -124,6 +126,19 @@ public async Task<string> GetIdentityToken()
             return await _authDelegator.GetIdentityToken();
         }
 
+        public async Task<string> GenerateAuthorizationSignature(WalletApiPayload payload)
+        {
+            byte[] encodedPayload = payload.EncodePayload();
+            byte[] signature = await _authorizationKey.Signature(encodedPayload);
+            return Convert.ToBase64String(signature);
+        }
+
+        public async Task<string> GenerateAuthorizationSignature(byte[] payload)
+        {
+            byte[] signature = await _authorizationKey.Signature(payload);
+            return Convert.ToBase64String(signature);
+        }
+
         // Public Methods
         public async Task<IEmbeddedEthereumWallet> CreateEthereumWallet(bool allowAdditional = false)
         {

SDK/Runtime/Core/PrivyImpl.cs

@@ -119,7 +119,7 @@ public PrivyImpl(PrivyConfig config)
             OAuth = new LoginWithOAuth(_authDelegator);
             Sms = new LoginWithSms(_authDelegator);
             _user = new PrivyUser(_authDelegator, _embeddedWalletManager, _appConfigRepository, walletApiWalletCreator,
-                walletApiRepository);
+                walletApiRepository, authorizationKey);
         }
 
         internal async Task InitializeAsync()

SDK/Runtime/EmbeddedWallet/WalletApi/WalletAuthorization/WalletApiPayload.cs

@@ -4,22 +4,26 @@
 
 namespace Privy.Wallets
 {
-    internal struct WalletApiPayload
+    /// <summary>
+    /// Represents an API request payload to be signed for authorization.
+    /// The signature can be included as the <c>privy-authorization-signature</c> header.
+    /// </summary>
+    public struct WalletApiPayload
     {
         [JsonProperty("version")]
-        internal int Version;
+        public int Version;
 
         [JsonProperty("url")]
-        internal string Url;
+        public string Url;
 
         [JsonProperty("method")]
-        internal string Method;
+        public string Method;
 
         [JsonProperty("headers")]
-        internal Dictionary<string, string> Headers;
+        public Dictionary<string, string> Headers;
 
         [JsonProperty("body")]
-        internal object Body;
+        public object Body;
 
         internal byte[] EncodePayload()
         {