Working implementation of PasswordManager

Quondam/PasswordManager.cs

@@ -1,26 +1,39 @@
 using System;
+using System.Web.Security;
 
 namespace MartinEden.Quondam
 {
     public class PasswordManager : IPasswordManager
     {
         private IClock clock;
+        private UserStore store;
+
+        internal static readonly TimeSpan MaximumPasswordAge = TimeSpan.FromSeconds(30);
 
         public PasswordManager()
             : this(new RealClock()) { }
         internal PasswordManager(IClock clock)
         {
             this.clock = clock;
+            store = new UserStore();
         }
 
         public string GenerateOneTimePassword(string username)
         {
-            throw new NotImplementedException();
+            string password = Membership.GeneratePassword(16, 0);
+            store.StorePassword(username, password, clock.Now);
+            return password;
         }
 
         public bool ValidatePassword(string username, string password)
         {
-            throw new NotImplementedException();
+            var record = store.GetPassword(username);
+            if (record != null && record.IsFresh(clock.Now) && record.Password == password)
+            {
+                store.ClearPassword(username);
+                return true;
+            }
+            return false;
         }
     }
 }

Quondam/PasswordRecord.cs

@@ -0,0 +1,21 @@
+using System;
+
+namespace MartinEden.Quondam
+{
+    internal class PasswordRecord
+    {
+        internal readonly string Password;
+        internal readonly DateTime Timestamp;
+
+        internal PasswordRecord(string password, DateTime timestamp)
+        {
+            Password = password;
+            Timestamp = timestamp;
+        }
+
+        internal bool IsFresh(DateTime now)
+        {
+            return (now - Timestamp) <= PasswordManager.MaximumPasswordAge;
+        }
+    }
+}

Quondam/Quondam.csproj

@@ -32,6 +32,7 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
+    <Reference Include="System.Web" />
     <Reference Include="System.Xml.Linq" />
     <Reference Include="System.Data.DataSetExtensions" />
     <Reference Include="Microsoft.CSharp" />
@@ -40,11 +41,13 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="PasswordRecord.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="RealClock.cs" />
     <Compile Include="IClock.cs" />
     <Compile Include="IPasswordManager.cs" />
     <Compile Include="PasswordManager.cs" />
+    <Compile Include="UserStore.cs" />
   </ItemGroup>
   <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />

Quondam/UserStore.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+
+namespace MartinEden.Quondam
+{
+    internal class UserStore
+    {
+        private Dictionary<string, PasswordRecord> records;
+
+        internal UserStore()
+        {
+            records = new Dictionary<string, PasswordRecord>();
+        }
+
+        internal void StorePassword(string username, string password, DateTime timestamp)
+        {
+            records[username] = new PasswordRecord(password, timestamp);
+        }
+
+        internal PasswordRecord GetPassword(string username)
+        {
+            PasswordRecord record;
+            if (records.TryGetValue(username, out record))
+            {
+                return record;
+            }
+            return null;
+        }
+
+        internal void ClearPassword(string username)
+        {
+            records.Remove(username);
+        }
+    }
+}