diff --git a/Sources/XXClient/Models/GroupMember.swift b/Sources/XXClient/Models/GroupMember.swift
index 8ce7120a58880ab94f9f8a590ad6872565684bfd..cb5d9843bce2a661bdeb93560fbc77860b71d28c 100644
--- a/Sources/XXClient/Models/GroupMember.swift
+++ b/Sources/XXClient/Models/GroupMember.swift
@@ -1,27 +1,40 @@
 import Foundation
 
 public struct GroupMember: Equatable {
-  public init(id: Data) {
+  public init(id: Data, dhKey: DHKey) {
     self.id = id
+    self.dhKey = dhKey
   }
 
   public var id: Data
+  public var dhKey: DHKey
 }
 
-extension GroupMember: Decodable {
+extension GroupMember: Codable {
   enum CodingKeys: String, CodingKey {
     case id = "ID"
+    case dhKey = "DhKey"
   }
 
   public static func decode(_ data: Data) throws -> Self {
-    let data = convertJsonNumberToString(in: data, minNumberLength: 19)
+    let data = convertJsonNumberToString(in: data, at: "Value")
     return try JSONDecoder().decode(Self.self, from: data)
   }
+
+  public func encode() throws -> Data {
+    let data = try JSONEncoder().encode(self)
+    return convertJsonStringToNumber(in: data, at: "Value")
+  }
 }
 
 extension Array where Element == GroupMember {
   public static func decode(_ data: Data) throws -> Self {
-    let data = convertJsonNumberToString(in: data, minNumberLength: 19)
+    let data = convertJsonNumberToString(in: data, at: "Value")
     return try JSONDecoder().decode(Self.self, from: data)
   }
+
+  public func encode() throws -> Data {
+    let data = try JSONEncoder().encode(self)
+    return convertJsonStringToNumber(in: data, at: "Value")
+  }
 }
diff --git a/Tests/XXClientTests/Models/GroupMemberTests.swift b/Tests/XXClientTests/Models/GroupMemberTests.swift
index 36e178c08f37b0bec719f4c3b7747043a9920491..eed1a4739d05b5832a40867c4842ccb18a280903 100644
--- a/Tests/XXClientTests/Models/GroupMemberTests.swift
+++ b/Tests/XXClientTests/Models/GroupMemberTests.swift
@@ -4,13 +4,15 @@ import XCTest
 
 final class GroupMemberTests: XCTestCase {
   func testCoding() throws {
-    let idB64 = "U4x/lrFkvxuXu59LtHLon1sUhPJSCcnZND6SugndnVID"
+    let idB64 = "SGVsbG8sIFdvcmxkISBHcm91cCBNZW1iZXIgVGVzdCBJRA=="
+    let dhKeyValue = "1759426033802606996617132861414734059978289057332806031357800676138355264622676606691435603603751978195460163638145821347601916259127578968570412642641025630452893097179266022832268525346700655861033031712000288680395716922501450233258587788020541937373196899001184700899008948530359980753630443486308876999029238453979779103124291315202352475056237021681172884599194016245219278368648568458514708567045834427853469072638665888791358582182353417065794210125797368093469194927663862565508608719835557592421245749381164023134450699040591219966988201315627676532245052123725278573237006510683695959381015415110970848376498637637944431576313526294020390694483472829278364602405292767170719547347485307956614210210673321959886410245334772057212077704024337636501108566655549055129066343309591274727538343075929837698653965640646190405582788894021694347212874155979958144038307500444865955516612526623220973497735316081265793063949"
+    let dhKeyFingerprint: UInt64 = 15989433043166758754
     let jsonString = """
     {
       "ID": "\(idB64)",
       "DhKey": {
-        "Value": 1759426033802606996617132861414734059978289057332806031357800676138355264622676606691435603603751978195460163638145821347601916259127578968570412642641025630452893097179266022832268525346700655861033031712000288680395716922501450233258587788020541937373196899001184700899008948530359980753630443486308876999029238453979779103124291315202352475056237021681172884599194016245219278368648568458514708567045834427853469072638665888791358582182353417065794210125797368093469194927663862565508608719835557592421245749381164023134450699040591219966988201315627676532245052123725278573237006510683695959381015415110970848376498637637944431576313526294020390694483472829278364602405292767170719547347485307956614210210673321959886410245334772057212077704024337636501108566655549055129066343309591274727538343075929837698653965640646190405582788894021694347212874155979958144038307500444865955516612526623220973497735316081265793063949,
-        "Fingerprint": 15989433043166758754
+        "Value": \(dhKeyValue),
+        "Fingerprint": \(dhKeyFingerprint)
       }
     }
     """
@@ -18,13 +20,34 @@ final class GroupMemberTests: XCTestCase {
     let model = try GroupMember.decode(jsonData)
 
     XCTAssertNoDifference(model, GroupMember(
-      id: Data(base64Encoded: idB64)!
+      id: Data(base64Encoded: idB64)!,
+      dhKey: DHKey(
+        value: dhKeyValue,
+        fingerprint: dhKeyFingerprint
+      )
     ))
 
+    let encodedModel = try model.encode()
+    let encodedModelString = String(data: encodedModel, encoding: .utf8)!
+    XCTAssertNoDifference(
+      encodedModelString,
+      """
+      {"ID":"\(idB64)","DhKey":{"Value":\(dhKeyValue),"Fingerprint":\(dhKeyFingerprint)}}
+      """
+    )
+
     let jsonArrayString = "[\(jsonString)]"
     let jsonArrayData = jsonArrayString.data(using: .utf8)!
     let decodedModels = try [GroupMember].decode(jsonArrayData)
 
     XCTAssertNoDifference(decodedModels, [model])
+
+    let encodedModels = try decodedModels.encode()
+    let encodedModelsString = String(data: encodedModels, encoding: .utf8)!
+
+    XCTAssertNoDifference(
+      encodedModelsString,
+      "[\(encodedModelString)]"
+    )
   }
 }