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aprismatic · Jan 19, 2022 · 4d2bcf1 · 4d2bcf1
1 parent d9b638a
commit 4d2bcf1
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Showing 3 changed files with 64 additions and 11 deletions.
diff --git a/src/Aprismatic.PohligHellman/Aprismatic.PohligHellman.csproj b/src/Aprismatic.PohligHellman/Aprismatic.PohligHellman.csproj
@@ -4,6 +4,6 @@
     <Description>Extension for the .NET Framework cryptography subsystem, which introduces the Pohlig-Hellman exponentiation cipher.</Description>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Aprismatic.BigIntegerExt" Version="0.1.8" />
+    <PackageReference Include="Aprismatic.BigIntegerExt" Version="0.1.10" />
   </ItemGroup>
 </Project>
diff --git a/src/Aprismatic.PohligHellman/PohligHellman.cs b/src/Aprismatic.PohligHellman/PohligHellman.cs
@@ -19,13 +19,14 @@ public class PohligHellman : IDisposable
         public PohligHellman(int keySize) {
             _rng = RandomNumberGenerator.Create();
             KeySize = keySize;
-            _keyStruct = CreateKeyPair();
+            var p = BigInteger.One.GenPseudoPrime(KeySize, 16, _rng);
+            _keyStruct = CreateKeyPair(p);
         }
 
-        public PohligHellman(BigInteger P) {
+        public PohligHellman(BigInteger p) {
             _rng = RandomNumberGenerator.Create();
-            KeySize = P.BitCount();
-            _keyStruct = CreateKeyPair(P);
+            KeySize = p.BitCount();
+            _keyStruct = CreateKeyPair(p);
         }
 
         // TODO: Consolidate constructors in one method
@@ -42,11 +43,6 @@ public PohligHellman(PohligHellmanParameters prms) {
         public PohligHellman(string xml) : this(PohligHellmanParameters.FromXml(xml)) { }
 
         // TODO: This method should probably move to KeyStruct
-        private PohligHellmanKeyStruct CreateKeyPair() {
-            var P = BigInteger.One.GenPseudoPrime(KeySize, 16, _rng);
-            return CreateKeyPair(P);
-        }
-
         private PohligHellmanKeyStruct CreateKeyPair(BigInteger P) {
             BigInteger E, D;
             var PminusOne = P - BigInteger.One;
@@ -62,7 +58,7 @@ private PohligHellmanKeyStruct CreateKeyPair(BigInteger P) {
 
         public byte[] EncryptData(BigInteger message) {
             if (message < 0 || message > MaxEncryptableValue)
-                throw new ArgumentException($"Value should be 0 <= m <= {MaxEncryptableValue}", nameof(message));
+                throw new ArgumentException($"Value should be 0 <= m <= {MaxEncryptableValue} under the current encryption key", nameof(message));
 
             var ctbs = _keyStruct.CiphertextLength;
             var array = new byte[ctbs];

diff --git a/test/PohligHellmanTests/MainTests.cs b/test/PohligHellmanTests/MainTests.cs
@@ -0,0 +1,57 @@
+using System;
+using System.Numerics;
+using System.Security.Cryptography;
+using Aprismatic;
+using Aprismatic.PohligHellman;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace PohligHellmanTests
+{
+    public class MainTests : IDisposable
+    {
+        private readonly ITestOutputHelper _output;
+
+        private readonly Random _rnd = new();
+        private readonly RandomNumberGenerator _rng = RandomNumberGenerator.Create();
+
+        public MainTests(ITestOutputHelper output) {
+            _output = output;
+        }
+
+        public void Dispose() {
+            _rng.Dispose();
+        }
+
+        [Fact(DisplayName = "Correctness")]
+        public void TestCorrectness() {
+            for (var i = 0; i < Globals.Iterations; i++) {
+                var ks = _rnd.Next(Globals.MinKeyLength, Globals.MaxKeyLength);
+                using var algorithm = new PohligHellman(ks);
+
+                Assert.Equal(ks, algorithm.KeySize);
+
+                var o = BigInteger.Zero.GenRandomBits(1, BigInteger.Pow(2, algorithm.KeySize - 1) - 1, _rng);
+
+                var o_enc = algorithm.EncryptData(o);
+                var o_dec = algorithm.DecryptData(o_enc);
+
+                Assert.Equal(o, o_dec);
+            }
+
+            for (var i = 0; i < Globals.Iterations; i++) {
+                var p = BigInteger.One.GenPseudoPrime(_rnd.Next(Globals.MinKeyLength, Globals.MaxKeyLength), 16, _rng);
+                using var algorithm = new PohligHellman(p);
+
+                Assert.Equal(p, algorithm.P);
+
+                var o = BigInteger.Zero.GenRandomBits(1, BigInteger.Pow(2, algorithm.KeySize - 1) - 1, _rng);
+
+                var o_enc = algorithm.EncryptData(o);
+                var o_dec = algorithm.DecryptData(o_enc);
+
+                Assert.Equal(o, o_dec);
+            }
+        }
+    }
+}