I am trying to generate public and private keys for an ECDH handshake. Back end is using p256 for public key. I am getting a failed request with status 0 public func makeHandShake(completion: @escaping (Bool, String?) -> ()) { guard let config = self.config else { completion(false,APP_CONFIG_ERROR) return } var rData = HandshakeRequestTwo() let sessionValue = AppUtils().generateSessionID() rData.session = sessionValue //generating my ECDH Key Pair let sPrivateKey = P256.KeyAgreement.PrivateKey() let sPublicKey = sPrivateKey.publicKey let privateKeyBase64 = sPrivateKey.rawRepresentation.base64EncodedString() print("My Private Key (Base64): \(privateKeyBase64)") let publicKeyBase64 = sPublicKey.rawRepresentation.base64EncodedString() print("My Public Key (Base64): \(publicKeyBase64)") rData.value = sPublicKey.rawRepresentation.base64EncodedString() let encoder = JSONEncoder() do { let jsonData = try encoder.encode(rData) if let jsonString = String(data: jsonData, encoding: .utf8) { print("Request Payload: \(jsonString)") } } catch { print("Error encoding request model to JSON: \(error)") completion(false, "Error encoding request model") return } self.rsaReqResponseHandler(config: config, endpoint: config.services.handShake.endpoint, model: rData) { resToDecode, error in print("Response received before guard : \(resToDecode ?? "No response")") guard let responseString = resToDecode else { print("response string is nil") completion(false,error) return } print("response received: \(responseString)") let decoder = JSONDecoder() do { let request = try decoder.decode(DefaultResponseTwo.self, from: Data(responseString.utf8)) let msg = request.message let status = request.status == 1 ? true : false completion(status,msg) guard let serverPublicKeyBase64 = request.data?.value else { print("Server response is missing the value") completion(false, config.messages.serviceError) return } print("Server Public Key (Base64): \(serverPublicKeyBase64)") if serverPublicKeyBase64.isEmpty { print("Server public key is an empty string.") completion(false, config.messages.serviceError) return } guard let serverPublicKeyData = Data(base64Encoded: serverPublicKeyBase64) else { print("Failed to decode server public key from Base64. Data is invalid.") completion(false, config.messages.serviceError) return } print("Decoded server public key data: \(serverPublicKeyData)") guard let serverPublicKey = try? P256.KeyAgreement.PublicKey(rawRepresentation: serverPublicKeyData) else { print("Decoded server public key data is invalid for P-256 format.") completion(false, config.messages.serviceError) return } // Derive Shared Secret and AES Key let sSharedSecret = try sPrivateKey.sharedSecretFromKeyAgreement(with: serverPublicKey) // Derive AES Key from Shared Secret let symmetricKey = sSharedSecret.hkdfDerivedSymmetricKey( using: SHA256.self, salt: "AES".data(using: .utf8) ?? Data(), sharedInfo: Data(), outputByteCount: 32 ) // Storing AES Key in Config let symmetricKeyBase64 = symmetricKey.withUnsafeBytes { Data($0) }.base64EncodedString() print("Derived Key: \(symmetricKeyBase64)") self.config?.cryptoConfig.key = symmetricKeyBase64 AppUtils.Log(from: self, with: "Handshake Successful, AES Key Established") } catch { AppUtils.Log(from: self, with: "Handshake Failed :: \(error)") completion(false, self.config?.messages.serviceError) } } } this is request struct model public struct HandshakeRequestTwo: Codable { public var session: String? public var value: String? public enum CodingKeys: CodingKey { case session case value } public init(session: String? = nil, value: String? = nil) { self.session = session self.value = value } } This is backend's response {"message":"Success","status":1,"data":{"senderId":"POSTBANK","value":"MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAErLxbfQzX+xnYVT1LLP5VOKtkMRVPRCoqYHcCRTM64EMEOaRU16yzsN+2PZMJc0HpdKNegJQZMmswZtg6U9JGVw=="}} This is my response struct model public struct DefaultResponseTwo: Codable { public var message: String? public var status: Int? public var data: HandshakeData? public init(message: String? = nil, status: Int? = nil, data: HandshakeData? = nil) { self.message = message self.status = status self.data = data } } public struct HandshakeData: Codable { public var senderId: String? public var value: String? public init(senderId: String? = nil, value: String? = nil) { self.senderId = senderId self.value = value } }