diff --git a/Sources/IndieWebKit/IndieAuth/AuthenticationRequest.swift b/Sources/IndieWebKit/IndieAuth/AuthenticationRequest.swift
index 5231825..9120c1c 100644
--- a/Sources/IndieWebKit/IndieAuth/AuthenticationRequest.swift
+++ b/Sources/IndieWebKit/IndieAuth/AuthenticationRequest.swift
@@ -7,7 +7,7 @@
 
 import Foundation
 import CryptoSwift
-import AuthenticationServices
+//import AuthenticationServices
 
 public class AuthenticationRequest {
     
@@ -19,18 +19,23 @@ public class AuthenticationRequest {
     private var codeChallenge: String?
     private let codeChallengeMethod = "S256"
     
-    private var url: URL? {
+    var url: URL? {
         var requestUrl = URLComponents(url: authorizationEndpoint, resolvingAgainstBaseURL: false)
-        requestUrl?.queryItems?.append(URLQueryItem(name: "me", value: profile.absoluteString))
-        requestUrl?.queryItems?.append(URLQueryItem(name: "client_id", value: clientId.absoluteString))
-        requestUrl?.queryItems?.append(URLQueryItem(name: "redirect_uri", value: redirectUri.absoluteString))
-        requestUrl?.queryItems?.append(URLQueryItem(name: "state", value: state))
+        var queryItems: [URLQueryItem] = []
+        
+        queryItems.append(URLQueryItem(name: "me", value: profile.absoluteString))
+        queryItems.append(URLQueryItem(name: "client_id", value: clientId.absoluteString))
+        queryItems.append(URLQueryItem(name: "redirect_uri", value: redirectUri.absoluteString))
+        queryItems.append(URLQueryItem(name: "state", value: state))
+        queryItems.append(URLQueryItem(name: "response_type", value: "id"))
         
         if codeChallenge != nil {
-            requestUrl?.queryItems?.append(URLQueryItem(name: "code_challenge", value: codeChallenge))
-            requestUrl?.queryItems?.append(URLQueryItem(name: "code_challenge_method", value: codeChallengeMethod))
+            queryItems.append(URLQueryItem(name: "code_challenge_method", value: codeChallengeMethod))
+            queryItems.append(URLQueryItem(name: "code_challenge", value: codeChallenge))
         }
         
+        requestUrl?.queryItems = queryItems
+        
         return requestUrl?.url
     }
     
@@ -47,34 +52,41 @@ public class AuthenticationRequest {
         }
     }
     
-    func start(completion: @escaping ((String?) -> ())) {
+    @available(iOS 12.0, macOS 10.15, *)
+    func start(completion: @escaping ((URL?) -> ())) {
         guard url != nil else {
             // TODO: Throw some type of error
             return
         }
         
-        ASWebAuthenticationSession(url: url!, callbackURLScheme: nil) { [weak self] responseUrl, error in
-            guard error == nil else {
-                // TODO: Throw some type of error
-                return
-            }
-            
-            guard responseUrl != nil else {
-                // TODO: Throw some type of error
-                return
-            }
-            
-            let authorizationCode = self?.parseResponse(responseUrl!)
-            guard authorizationCode != nil else {
-                // TODO: Throw an error because authorization code should not be nil
-                return
-            }
-            
-            verifyAuthenticationCode(authorizationCode!)
-        }.start()
+//        ASWebAuthenticationSession(url: url!, callbackURLScheme: nil) { [weak self] responseUrl, error in
+//            guard error == nil else {
+//                // TODO: Throw some type of error
+//                return
+//            }
+//
+//            guard responseUrl != nil else {
+//                // TODO: Throw some type of error
+//                return
+//            }
+//
+//            let authorizationCode = self?.parseResponse(responseUrl!)
+//            guard authorizationCode != nil else {
+//                // TODO: Throw an error because authorization code should not be nil
+//                return
+//            }
+//
+//            self?.verifyAuthenticationCode(authorizationCode!) { [weak self] codeVerified in
+//                if (codeVerified) {
+//                    completion(self?.profile)
+//                } else {
+//                    completion(nil)
+//                }
+//            }
+//        }.start()
     }
     
-    private func parseResponse(_ responseUrl: URL) -> String {
+    func parseResponse(_ responseUrl: URL) -> String {
         let responseComponents = URLComponents(url: responseUrl, resolvingAgainstBaseURL: false)
         var state = ""
         var code = ""
@@ -95,16 +107,71 @@ public class AuthenticationRequest {
         return code
     }
     
-    private func verifyAuthenticationCode(_ code: String) {
-        // TODO: Resume #5 here
+    func verifyAuthenticationCode(_ code: String, completion: @escaping ((Bool) -> Void)) {
+        
+        do {
+            let verificationRequest = try getVerificationRequest(with: code)
+            
+            URLSession.shared.dataTask(with: verificationRequest) { [weak self] body, response, error in
+                guard error == nil else {
+                    // TODO: Throw error here
+                    return
+                }
+                
+                // TODO: Check to make sure content type is application/json
+                
+                guard body != nil else {
+                    // TODO: throw error here
+                    return
+                }
+                
+                let responseProfile = try! JSONDecoder().decode([String:URL].self, from: body!)
+                
+                completion(self!.confirmVerificationResponse(responseProfile))
+                
+                }.resume()
+            
+        } catch {
+            // TODO: Figure out how to report error
+            completion(false)
+        }
+    }
+    
+    func getVerificationRequest(with code: String) throws -> URLRequest {
+        var request = URLRequest(url: authorizationEndpoint)
+        request.httpMethod = "POST"
+        request.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
+        request.addValue("application/json", forHTTPHeaderField: "Accept")
+        
+        let postBody = [
+            "code": code,
+            "client_id": clientId.absoluteString,
+            "redirect_uri": redirectUri.absoluteString
+        ]
+        
+        try request.httpBody = JSONEncoder().encode(postBody)
+        
+        return request
     }
     
-    private func generateDefaultCodeChallenge() -> String? {
-        return Data(base64Encoded: randomString(length: 128).sha256())?.base64EncodedString()
+    func confirmVerificationResponse(_ responseProfile: [String:URL]) -> Bool {
+        guard responseProfile["me"] != nil else {
+            return false
+        }
+        
+        let meComponents = URLComponents(url: responseProfile["me"]!, resolvingAgainstBaseURL: false)
+        let profileComponents = URLComponents(url: profile, resolvingAgainstBaseURL: false)
+        
+        let validProfile = meComponents?.host == profileComponents?.host
+        
+        if (validProfile) {
+            profile = responseProfile["me"]!
+        }
+        
+        return validProfile
     }
     
-    private func randomString(length: Int) -> String {
-        let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~"
-        return String((0..<length).map{ _ in letters.randomElement()! })
+    private func generateDefaultCodeChallenge() -> String? {
+        return Data(base64Encoded: String.randomString(length: 128).sha256())?.base64EncodedString()
     }
 }
diff --git a/Sources/IndieWebKit/String.extension.swift b/Sources/IndieWebKit/String.extension.swift
new file mode 100644
index 0000000..60ca538
--- /dev/null
+++ b/Sources/IndieWebKit/String.extension.swift
@@ -0,0 +1,24 @@
+//
+//  File.swift
+//  
+//
+//  Created by ehinkle-ad on 6/11/19.
+//
+
+import Foundation
+extension String {
+    public static func randomString(length: Int) -> String {
+        let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~"
+        return randomString(length: length, from: letters)
+    }
+    
+    public static func randomAlphaNumericString(length: Int) -> String {
+        let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+        return randomString(length: length, from: letters)
+    }
+    
+    public static func randomString(length: Int, from stringOptions: String) -> String {
+        let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~"
+        return String((0..<length).map{ _ in letters.randomElement()! })
+    }
+}
diff --git a/Tests/IndieWebKitTests/IndieAuthTests.swift b/Tests/IndieWebKitTests/IndieAuthTests.swift
index e940321..1293350 100644
--- a/Tests/IndieWebKitTests/IndieAuthTests.swift
+++ b/Tests/IndieWebKitTests/IndieAuthTests.swift
@@ -152,8 +152,111 @@ final class IndieAuthTests: XCTestCase {
         
     }
     
-    func testAuthenticationRequest() {
+    // IndieAuth Spec 5.2 Building Authentication Request URL
+    // https://indieauth.spec.indieweb.org/#authentication-request
+    func testAuthenticationRequestUrl() {
         
+        let profile = URL(string: "https://eddiehinkle.com")!
+        let authorization_endpoint = URL(string: "https://eddiehinkle.com/auth")!
+        let client_id = URL(string: "https://remark.social")!
+        let redirect_uri = URL(string: "https://remark.social/ios/callback")!
+        let state = String.randomAlphaNumericString(length: 25)
+        
+        let request = AuthenticationRequest(for: profile,
+                              at: authorization_endpoint,
+                              clientId: client_id,
+                              redirectUri: redirect_uri,
+                              state: state,
+                              codeChallenge: nil)
+     
+        XCTAssertTrue(request.url!.absoluteString.contains("\(authorization_endpoint)?me=\(profile)&client_id=\(client_id)&redirect_uri=\(redirect_uri)&state=\(state)&response_type=id&code_challenge_method=S256&code_challenge="))
+    }
+    
+    // IndieAuth Spec 5.3 Parsing the Authentication Response
+    // https://indieauth.spec.indieweb.org/#authentication-response
+    func testParseAuthenticationResponse() {
+        let profile = URL(string: "https://eddiehinkle.com")!
+        let authorization_endpoint = URL(string: "https://eddiehinkle.com/auth")!
+        let client_id = URL(string: "https://remark.social")!
+        let redirect_uri = URL(string: "https://remark.social/ios/callback")!
+        let state = String.randomAlphaNumericString(length: 25)
+        
+        let request = AuthenticationRequest(for: profile,
+                                            at: authorization_endpoint,
+                                            clientId: client_id,
+                                            redirectUri: redirect_uri,
+                                            state: state,
+                                            codeChallenge: nil)
+        
+        let authorization_code_from_server = String.randomAlphaNumericString(length: 20)
+        
+        let parsed_authorization_code = request.parseResponse(URL(string: "\(redirect_uri)?code=\(authorization_code_from_server)&state=\(state)")!)
+        XCTAssertEqual(parsed_authorization_code, authorization_code_from_server)
+    }
+    
+    // IndieAuth Spec 5.4 Authorization Code Verification Request
+    // https://indieauth.spec.indieweb.org/#authorization-code-verification
+    func testAuthorizationCodeVerificationRequest() {
+        
+        let profile = URL(string: "https://eddiehinkle.com")!
+        let authorization_endpoint = URL(string: "https://eddiehinkle.com/auth")!
+        let client_id = URL(string: "https://remark.social")!
+        let redirect_uri = URL(string: "https://remark.social/ios/callback")!
+        let state = String.randomAlphaNumericString(length: 25)
+        
+        let request = AuthenticationRequest(for: profile,
+                                            at: authorization_endpoint,
+                                            clientId: client_id,
+                                            redirectUri: redirect_uri,
+                                            state: state,
+                                            codeChallenge: nil)
+        
+        let authorization_code = String.randomAlphaNumericString(length: 20)
+        
+        let verificationRequest: URLRequest = try! request.getVerificationRequest(with: authorization_code)
+        
+        XCTAssertEqual(verificationRequest.httpMethod, "POST")
+        XCTAssertEqual(verificationRequest.url, authorization_endpoint)
+        
+        let bodyDictionary = try! JSONDecoder().decode([String:String].self, from: verificationRequest.httpBody!)
+        
+        XCTAssertEqual(bodyDictionary["code"], authorization_code)
+        XCTAssertEqual(bodyDictionary["client_id"], client_id.absoluteString)
+        XCTAssertEqual(bodyDictionary["redirect_uri"], redirect_uri.absoluteString)
+    }
+    
+    // IndieAuth Spec 5.4 Authorization Code Verification Response
+    // https://indieauth.spec.indieweb.org/#authorization-code-verification
+    func testAuthorizationCodeVerificationResponse() {
+        
+        let profile = URL(string: "https://eddiehinkle.com")!
+        let authorization_endpoint = URL(string: "https://eddiehinkle.com/auth")!
+        let client_id = URL(string: "https://remark.social")!
+        let redirect_uri = URL(string: "https://remark.social/ios/callback")!
+        let state = String.randomAlphaNumericString(length: 25)
+        
+        let request = AuthenticationRequest(for: profile,
+                                            at: authorization_endpoint,
+                                            clientId: client_id,
+                                            redirectUri: redirect_uri,
+                                            state: state,
+                                            codeChallenge: nil)
+        
+        let sameProfile = profile
+        let responseWithSameProfile = [ "me": sameProfile ]
+        let isValidMe = request.confirmVerificationResponse(responseWithSameProfile)
+        XCTAssertTrue(isValidMe)
+        
+        var subProfile = URLComponents(url: profile, resolvingAgainstBaseURL: false)!
+        subProfile.path = "/path/under"
+        let responseWithSubProfile = [ "me": subProfile.url! ]
+        let isValidMe2 = request.confirmVerificationResponse(responseWithSubProfile)
+        XCTAssertTrue(isValidMe2)
+        
+        let spoofedProfile = URL(string: "https://spoofing.com")!
+        let responseWithSpoofedProfile = [ "me": spoofedProfile ]
+        let isValidMe3 = request.confirmVerificationResponse(responseWithSpoofedProfile)
+        XCTAssertFalse(isValidMe3)
     }
     
     // TODO: Write a test that returns several of the same endpoint and make sure that the FIRST endpoint is used