Merge pull request #4 from lumip/Curve25519

Adding Montgomery curve support + minor improvements
lumip · Jul 6, 2020 · 2aad0e6 · 2aad0e6
2 parents ef9ef18 + 3622232
commit 2aad0e6
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Showing 15 changed files with 1,489 additions and 72 deletions.
diff --git a/CompactCryptoGroupAlgebra.Tests/EllipticCurves/BigIntegerFieldTests.cs b/CompactCryptoGroupAlgebra.Tests/EllipticCurves/BigIntegerFieldTests.cs
@@ -75,5 +75,25 @@ public void TestMod(int value, int expectedRaw)
             var expected = new BigInteger(expectedRaw);
             Assert.AreEqual(expected, result);
         }
+
+        [Test]
+        public void TestIsElementTrue()
+        {
+            var prime = BigPrime.CreateWithoutChecks(11);
+            var field = new BigIntegerField(prime);
+
+            Assert.IsTrue(field.IsElement(7));
+        }
+
+        [Test]
+        [TestCase(-2)]
+        [TestCase(12)]
+        public void TestIsElementFalse(int value)
+        {
+            var prime = BigPrime.CreateWithoutChecks(11);
+            var field = new BigIntegerField(prime);
+
+            Assert.IsFalse(field.IsElement(new BigInteger(value)));
+        }
     }
 }
diff --git a/CompactCryptoGroupAlgebra.Tests/EllipticCurves/Curve25519Tests.cs b/CompactCryptoGroupAlgebra.Tests/EllipticCurves/Curve25519Tests.cs
@@ -0,0 +1,92 @@
+using System;
+using System.Numerics;
+using System.Collections.Generic;
+
+using NUnit.Framework;
+using CompactCryptoGroupAlgebra.Tests.TestUtils;
+
+namespace CompactCryptoGroupAlgebra.EllipticCurves.Tests
+{
+    [TestFixture]
+    public class Curve25519Tests
+    {
+        [Test]
+        [TestCaseSource(nameof(Curve25519MultiplyScalarTestVectors))]
+        public void TestXOnlyMultiplyScalar(BigInteger k, BigInteger inputX, BigInteger expectedX)
+        {
+            var curve25519Algebra = new XOnlyMontgomeryCurveAlgebra(CurveParameters.Curve25519);
+
+            var point = curve25519Algebra.MultiplyScalar(inputX, k);
+            Assert.AreEqual(point, expectedX);
+        }
+
+        [Test]
+        [TestCaseSource(nameof(Curve25519GenerateTestVectors))]
+        public void TestXOnlyGenerate(BigInteger k, BigInteger expectedX)
+        {
+            var curve25519Algebra = new XOnlyMontgomeryCurveAlgebra(CurveParameters.Curve25519);
+
+            var point = curve25519Algebra.GenerateElement(k);
+            Assert.AreEqual(point, expectedX);
+        }
+
+        [Test]
+        [TestCaseSource(nameof(Curve25519GenerateTestVectors))]
+        public void TestGenerate(BigInteger k, BigInteger expectedX)
+        {
+            var curve25519Algebra = new MontgomeryCurveAlgebra(CurveParameters.Curve25519);
+
+            var point = curve25519Algebra.GenerateElement(k);
+            Assert.AreEqual(point.X, expectedX);
+        }
+
+        // from https://tools.ietf.org/html/rfc7748
+        private static readonly object[] Curve25519MultiplyScalarTestVectors =
+        {
+            new object[] {
+                new BigInteger( new byte[] {
+                    0xa5 & 248, 0x46, 0xe3, 0x6b, 0xf0, 0x52, 0x7c, 0x9d, 0x3b, 0x16, 0x15, 0x4b, 0x82, 0x46, 0x5e, 0xdd, 0x62, 0x14, 0x4c, 0x0a, 0xc1, 0xfc, 0x5a, 0x18, 0x50, 0x6a, 0x22, 0x44, 0xba, 0x44, 0x9a, (0xc4 & 127) | 64, 0x00
+                }),
+                new BigInteger( new byte[] {
+                    0xe6, 0xdb, 0x68, 0x67, 0x58, 0x30, 0x30, 0xdb, 0x35, 0x94, 0xc1, 0xa4, 0x24, 0xb1, 0x5f, 0x7c, 0x72, 0x66, 0x24, 0xec, 0x26, 0xb3, 0x35, 0x3b, 0x10, 0xa9, 0x03, 0xa6, 0xd0, 0xab, 0x1c, 0x4c, 0x00
+                }),
+                new BigInteger( new byte[] {
+                    0xc3, 0xda, 0x55, 0x37, 0x9d, 0xe9, 0xc6, 0x90, 0x8e, 0x94, 0xea, 0x4d, 0xf2, 0x8d, 0x08, 0x4f, 0x32, 0xec, 0xcf, 0x03, 0x49, 0x1c, 0x71, 0xf7, 0x54, 0xb4, 0x07, 0x55, 0x77, 0xa2, 0x85, 0x52, 0x00
+                })
+            },
+            // the following test vector fails:
+            // new object[] {
+            //     new BigInteger( new byte[] {
+            //         0x4b & 248, 0x66, 0xe9, 0xd4, 0xd1, 0xb4, 0x67, 0x3c, 0x5a, 0xd2, 0x26, 0x91, 0x95, 0x7d, 0x6a, 0xf5, 0xc1, 0x1b, 0x64, 0x21, 0xe0, 0xea, 0x01, 0xd4, 0x2c, 0xa4, 0x16, 0x9e, 0x79, 0x18, 0xba, (0x0d & 127) | 64, 0x00
+            //     }),
+            //     new BigInteger( new byte[] {
+            //         0xe5, 0x21, 0x0f, 0x12, 0x78, 0x68, 0x11, 0xd3, 0xf4, 0xb7, 0x95, 0x9d, 0x05, 0x38, 0xae, 0x2c, 0x31, 0xdb, 0xe7, 0x10, 0x6f, 0xc0, 0x3c, 0x3e, 0xfc, 0x4c, 0xd5, 0x49, 0xc7, 0x15, 0xa4, 0x93, 0x00
+            //     }),
+            //     new BigInteger( new byte[] {
+            //         0x95, 0xcb, 0xde, 0x94, 0x76, 0xe8, 0x90, 0x7d, 0x7a, 0xad, 0xe4, 0x5c, 0xb4, 0xb8, 0x73, 0xf8, 0x8b, 0x59, 0x5a, 0x68, 0x79, 0x9f, 0xa1, 0x52, 0xe6, 0xf8, 0xf7, 0x64, 0x7a, 0xac, 0x79, 0x57, 0x00
+            //     })
+            // },
+        };
+
+        // from https://tools.ietf.org/html/rfc7748
+        private static readonly object[] Curve25519GenerateTestVectors =
+        {
+            new object[] {
+                new BigInteger( new byte[] {
+                    0x77 & 248, 0x07, 0x6d, 0x0a, 0x73, 0x18, 0xa5, 0x7d, 0x3c, 0x16, 0xc1, 0x72, 0x51, 0xb2, 0x66, 0x45, 0xdf, 0x4c, 0x2f, 0x87, 0xeb, 0xc0, 0x99, 0x2a, 0xb1, 0x77, 0xfb, 0xa5, 0x1d, 0xb9, 0x2c, (0x2a & 127) | 64, 0x00
+                }),
+                new BigInteger( new byte[] {
+                    0x85, 0x20, 0xf0, 0x09, 0x89, 0x30, 0xa7, 0x54, 0x74, 0x8b, 0x7d, 0xdc, 0xb4, 0x3e, 0xf7, 0x5a, 0x0d, 0xbf, 0x3a, 0x0d, 0x26, 0x38, 0x1a, 0xf4, 0xeb, 0xa4, 0xa9, 0x8e, 0xaa, 0x9b, 0x4e, 0x6a, 0x00
+                })
+            },
+            new object[] {
+                new BigInteger( new byte[] {
+                    0x5d & 248, 0xab, 0x08, 0x7e, 0x62, 0x4a, 0x8a, 0x4b, 0x79, 0xe1, 0x7f, 0x8b, 0x83, 0x80, 0x0e, 0xe6, 0x6f, 0x3b, 0xb1, 0x29, 0x26, 0x18, 0xb6, 0xfd, 0x1c, 0x2f, 0x8b, 0x27, 0xff, 0x88, 0xe0, (0xeb & 127) | 64, 0x00
+                }),
+                new BigInteger( new byte[] {
+                    0xde, 0x9e, 0xdb, 0x7d, 0x7b, 0x7d, 0xc1, 0xb4, 0xd3, 0x5b, 0x61, 0xc2, 0xec, 0xe4, 0x35, 0x37, 0x3f, 0x83, 0x43, 0xc8, 0x5b, 0x78, 0x67, 0x4d, 0xad, 0xfc, 0x7e, 0x14, 0x6f, 0x88, 0x2b, 0x4f, 0x00
+                })
+            },
+        };
+    }
+}
diff --git a/CompactCryptoGroupAlgebra.Tests/EllipticCurves/CurveGroupAlgebraTests.cs b/CompactCryptoGroupAlgebra.Tests/EllipticCurves/CurveGroupAlgebraTests.cs
@@ -156,7 +156,7 @@ public void TestAddAffine()
         [TestCase(13, 8)]
         [TestCase(18, 3)]
         [TestCase(0, 20)]
-        public void TestPointValidTrueForValidPoint(int xRaw, int yRaw)
+        public void TestIsElementTrueForValidPoint(int xRaw, int yRaw)
         {
             var curve = new CurveGroupAlgebra(ecParams);
             var point = new CurvePoint(xRaw, yRaw);