diff --git a/jwt.zig b/jwt.zig
index 89031ec..a22125f 100644
--- a/jwt.zig
+++ b/jwt.zig
@@ -14,6 +14,14 @@ const Algorithm = enum {
     pub fn jsonStringify(value: Self, options: std.json.StringifyOptions, writer: anytype) @TypeOf(writer).Error!void {
         try std.json.stringify(std.meta.tagName(value), options, writer);
     }
+
+    pub fn CryptoFn(self: Self) type {
+        return switch (self) {
+            .HS256 => std.crypto.auth.hmac.sha2.HmacSha256,
+            .HS384 => std.crypto.auth.hmac.sha2.HmacSha384,
+            .HS512 => std.crypto.auth.hmac.sha2.HmacSha512,
+        };
+    }
 };
 
 const JWTType = enum {
@@ -63,11 +71,7 @@ pub fn encodeMessage(allocator: *std.mem.Allocator, comptime alg: Algorithm, mes
     jwt_text.items[protected_header_base64_len] = '.';
     _ = base64url.Encoder.encode(message_base64, message);
 
-    const signature = switch (signatureOptions.alg) {
-        .HS256 => &generate_signature_hmac_sha256(signatureOptions.key, protected_header_base64, message_base64),
-        .HS384 => &generate_signature_hmac_sha384(signatureOptions.key, protected_header_base64, message_base64),
-        .HS512 => &generate_signature_hmac_sha512(signatureOptions.key, protected_header_base64, message_base64),
-    };
+    const signature = &generate_signature(alg, signatureOptions.key, protected_header_base64, message_base64);
     const signature_base64_len = base64url.Encoder.calcSize(signature.len);
 
     try jwt_text.resize(message_base64_len + 1 + protected_header_base64_len + 1 + signature_base64_len);
@@ -185,11 +189,7 @@ pub fn validateMessage(allocator: *std.mem.Allocator, comptime expectedAlg: Algo
                 defer allocator.free(signature);
                 try base64url.Decoder.decode(signature, signature_base64);
 
-                const gen_sig = switch (signatureOptions.alg) {
-                    .HS256 => &generate_signature_hmac_sha256(signatureOptions.key, jose_base64, payload_base64),
-                    .HS384 => &generate_signature_hmac_sha384(signatureOptions.key, jose_base64, payload_base64),
-                    .HS512 => &generate_signature_hmac_sha512(signatureOptions.key, jose_base64, payload_base64),
-                };
+                const gen_sig = &generate_signature(expectedAlg, signatureOptions.key, jose_base64, payload_base64);
                 if (!std.mem.eql(u8, signature, gen_sig)) {
                     return error.InvalidSignature;
                 }
@@ -225,40 +225,14 @@ pub fn validateMessage(allocator: *std.mem.Allocator, comptime expectedAlg: Algo
     return message;
 }
 
-const HmacSha256 = std.crypto.auth.hmac.sha2.HmacSha256;
-pub fn generate_signature_hmac_sha256(key: []const u8, protectedHeaderBase64: []const u8, payloadBase64: []const u8) [HmacSha256.mac_length]u8 {
-    var h = HmacSha256.init(key);
+pub fn generate_signature(comptime algo: Algorithm, key: []const u8, protectedHeaderBase64: []const u8, payloadBase64: []const u8) [algo.CryptoFn().mac_length]u8 {
+    const T = algo.CryptoFn();
+    var h = T.init(key);
     h.update(protectedHeaderBase64);
     h.update(".");
     h.update(payloadBase64);
 
-    var out: [HmacSha256.mac_length]u8 = undefined;
-    h.final(&out);
-
-    return out;
-}
-
-const HmacSha384 = std.crypto.auth.hmac.sha2.HmacSha384;
-pub fn generate_signature_hmac_sha384(key: []const u8, protectedHeaderBase64: []const u8, payloadBase64: []const u8) [HmacSha384.mac_length]u8 {
-    var h = HmacSha384.init(key);
-    h.update(protectedHeaderBase64);
-    h.update(".");
-    h.update(payloadBase64);
-
-    var out: [HmacSha384.mac_length]u8 = undefined;
-    h.final(&out);
-
-    return out;
-}
-
-const HmacSha512 = std.crypto.auth.hmac.sha2.HmacSha512;
-pub fn generate_signature_hmac_sha512(key: []const u8, protectedHeaderBase64: []const u8, payloadBase64: []const u8) [HmacSha512.mac_length]u8 {
-    var h = HmacSha512.init(key);
-    h.update(protectedHeaderBase64);
-    h.update(".");
-    h.update(payloadBase64);
-
-    var out: [HmacSha512.mac_length]u8 = undefined;
+    var out: [T.mac_length]u8 = undefined;
     h.final(&out);
 
     return out;