chore: update readme

README.md

@@ -2,24 +2,97 @@
 [![Swift Package Manager compatible](https://img.shields.io/badge/Swift_Package_Manager-compatible-brightgreen.svg?style=flat&colorA=28a745&&colorB=4E4E4E)](https://github.com/apple/swift-package-manager)
 # Xenissuing 
 
-The XenIssuing SDK includes a collection of modules designed to handle sensitive operations with ease and security in your iOS applications. Notably:
-- SecureSession: This module is responsible for ensuring encrypted communication between the XenIssuing SDK and your iOS application.
+The XenIssuing SDK provides a secure way to handle sensitive operations in your iOS applications. This SDK includes:
+- **SecureSession**: A module that ensures encrypted communication between your application and Xendit's services.
 
 ## Prerequisites
 
-To utilize the XenIssuing SDK, a public key granted by Xendit is required. You can obtain this key by contacting Xendit directly.
+- iOS 10.15 or later
+- Swift 5.0 or later
+- A public key from Xendit (Contact Xendit to obtain this)
 
 ## Usage
 
-### Establishing Secure Sessions
+### Creating a Secure Session
 
-The SecureSession module aids in establishing an encrypted communication link between the XenIssuing SDK and your application. Below is a Swift example demonstrating how to create a secure session and decrypt card data:
+1. First, initialize a secure session with your Xendit public key:
 
 ```swift
 import Xenissuing
 
-let secureSession = try Xenissuing.createSecureSession(xenditPublicKeyData: Data(base64Encoded: validPublicKey)!)
-let sessionId = secureSession.getKey().base64EncodedString()
+let publicKey = """
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA... // Your RSA public key without header/footer
+"""
 
-let decryptedData = secureSession.decryptCardData(secret: secret, iv: iv)
+do {
+    // Create secure session
+    let secureSession = try Xenissuing.createSecureSession(
+        xenditPublicKeyData: Data(base64Encoded: publicKey)!
+    )
+
+    // Get session key (for validation)
+    let sessionKey = secureSession.getKey().base64EncodedString()
+
+    // Get encrypted session ID and URL encode it for API requests
+    let sessionId = secureSession.getEncryptedKey().base64EncodedString()
+
+    // Important: URL encode the session ID as it will be used as a URL parameter
+    let allowedCharacters = CharacterSet(charactersIn: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
+    let encodedSessionId = sessionId.addingPercentEncoding(withAllowedCharacters: allowedCharacters) ?? ""
+
+    // Use encodedSessionId when making API requests, for example:
+    // https://api.xendit.co/your/endpoint?session_id={encodedSessionId}
+} catch {
+    print("Error creating secure session:", error)
+}
 ```
+
+### Public Key Format
+
+The public key should be:
+- An RSA public key provided by Xendit
+- Without the "-----BEGIN PUBLIC KEY-----" and "-----END PUBLIC KEY-----" headers
+- A single continuous string (can use Swift multi-line string format for readability)
+
+Example format:
+```swift
+let publicKey = """
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA...
+"""
+```
+
+### Session ID Usage
+
+The session ID must be URL encoded because:
+- It contains base64 characters that may include '+' and '/'
+- It will be used as a URL parameter in API requests
+- URL encoding ensures safe transmission of the session ID in HTTP requests
+
+Example API usage:
+```swift
+let apiUrl = "https://api.xendit.co/card_issuing//cards/\(cardId)/pan?session_id=\(encodedSessionId)"
+```
+
+### Decrypting Card Data
+
+When you receive encrypted card data from Xendit's API:
+
+```swift
+do {
+    let decryptedData = try secureSession.decryptCardData(
+        secret: encryptedCardData, // Base64 encoded encrypted data
+        iv: initializationVector   // Base64 encoded IV
+    )
+
+    // Process the decrypted card data
+    let cardInfo = String(data: decryptedData, encoding: .utf8)
+} catch {
+    print("Decryption error:", error)
+}
+```
+
+## Support
+
+For issues, questions, or assistance, please reach out to the XenIssuing team at Xendit.
+- Email: [email protected]
+- API Documentation: https://developers.xendit.co