Added CreateCryptoGroup(securityLevel) to CurveGroupAlgebra and LibCrypto/EllipticCurveAlgebra.

Author: lumip

CompactCryptoGroupAlgebra.LibCrypto.Tests/EllipticCurves/EllipticCurveAlgebraTests.cs

@@ -1,6 +1,6 @@
 // CompactCryptoGroupAlgebra.LibCrypto - OpenSSL libcrypto implementation of CompactCryptoGroupAlgebra interfaces
 
-// SPDX-FileCopyrightText: 2021 Lukas Prediger <lumip@lumip.de>
+// SPDX-FileCopyrightText: 2022 Lukas Prediger <lumip@lumip.de>
 // SPDX-License-Identifier: GPL-3.0-or-later WITH GPL-3.0-linking-exception
 // SPDX-FileType: SOURCE
 
@@ -329,6 +329,27 @@ public void TestCreateCryptoGroup()
             Assert.That(group.Algebra.Equals(expectedGroupAlgebra));
         }
 
+        [Test]
+        [TestCase(126)]
+        [TestCase(128)]
+        [TestCase(140)]
+        [TestCase(190)]
+        [TestCase(200)]
+        [TestCase(254)]
+        [TestCase(260)]
+        public void TestCreateCryptoGroupWithSecurityLevel(int securityLevel)
+        {
+            var group = EllipticCurveAlgebra.CreateCryptoGroup(securityLevel);
+            Assert.That(group.SecurityLevel >= securityLevel);
+        }
+
+        [Test]
+        public void TestCreateCryptoGroupWithTooHighSecurityLevel()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => EllipticCurveAlgebra.CreateCryptoGroup(261));
+        }
+        
+
     }
 
 }

CompactCryptoGroupAlgebra.LibCrypto/EllipticCurves/EllipticCurveAlgebra.cs

@@ -1,6 +1,6 @@
 // CompactCryptoGroupAlgebra.LibCrypto - OpenSSL libcrypto implementation of CompactCryptoGroupAlgebra interfaces
 
-// SPDX-FileCopyrightText: 2021 Lukas Prediger <lumip@lumip.de>
+// SPDX-FileCopyrightText: 2022 Lukas Prediger <lumip@lumip.de>
 // SPDX-License-Identifier: GPL-3.0-or-later WITH GPL-3.0-linking-exception
 // SPDX-FileType: SOURCE
 
@@ -336,6 +336,34 @@ public static CryptoGroup<SecureBigNumber, ECPoint> CreateCryptoGroup(EllipticCu
             return new CryptoGroup<SecureBigNumber, ECPoint>(new EllipticCurveAlgebra(curveId));
         }
 
+        /// <summary>
+        /// Creates a <see cref="CryptoGroup{SecureBigNumber, ECPoint}" /> instance at least satisfying the given security level.
+        /// </summary>
+        /// <param name="securityLevel">The minimal security level for the curve to be created.</param>
+        public static CryptoGroup<SecureBigNumber, ECPoint> CreateCryptoGroup(int securityLevel)
+        {
+            EllipticCurveID curveId;
+            if (securityLevel <= 128)
+            {
+                curveId = EllipticCurveID.Prime256v1; // == Secp256r1
+            }
+            else if (securityLevel <= 192)
+            {
+                curveId = EllipticCurveID.Secp384r1;
+            }
+            else if (securityLevel <= 260)
+            {
+                curveId = EllipticCurveID.Secp521r1;
+            }
+            else
+            {
+                throw new ArgumentOutOfRangeException(
+                    $"There are no curves that satisfy a security level of {securityLevel}.", nameof(securityLevel)
+                );
+            }
+            return CreateCryptoGroup(curveId);
+        }
+
     }
 
 }

CompactCryptoGroupAlgebra.Tests/EllipticCurves/CurveGroupAlgebraTests.cs

@@ -1,6 +1,6 @@
 // CompactCryptoGroupAlgebra - C# implementation of abelian group algebra for experimental cryptography
 
-// SPDX-FileCopyrightText: 2020-2021 Lukas Prediger <lumip@lumip.de>
+// SPDX-FileCopyrightText: 2022 Lukas Prediger <lumip@lumip.de>
 // SPDX-License-Identifier: GPL-3.0-or-later
 // SPDX-FileType: SOURCE
 
@@ -369,5 +369,26 @@ public void TestCreateCryptoGroup()
             var group = CurveGroupAlgebra.CreateCryptoGroup(curveParameters);
             Assert.AreEqual(expectedGroupAlgebra, group.Algebra);
         }
+
+        [Test]
+        [TestCase(126)]
+        [TestCase(128)]
+        [TestCase(140)]
+        [TestCase(190)]
+        [TestCase(200)]
+        [TestCase(254)]
+        [TestCase(260)]
+        public void TestCreateCryptoGroupWithSecurityLevel(int securityLevel)
+        {
+            var group = CurveGroupAlgebra.CreateCryptoGroup(securityLevel);
+            Assert.That(group.SecurityLevel >= securityLevel);
+        }
+
+        [Test]
+        public void TestCreateCryptoGroupWithTooHighSecurityLevel()
+        {
+            Assert.Throws<ArgumentOutOfRangeException>(() => CurveGroupAlgebra.CreateCryptoGroup(261));
+        }
+
     }
 }

CompactCryptoGroupAlgebra/EllipticCurves/CurveGroupAlgebra.cs

@@ -1,6 +1,6 @@
 // CompactCryptoGroupAlgebra - C# implementation of abelian group algebra for experimental cryptography
 
-// SPDX-FileCopyrightText: 2020-2021 Lukas Prediger <lumip@lumip.de>
+// SPDX-FileCopyrightText: 2022 Lukas Prediger <lumip@lumip.de>
 // SPDX-License-Identifier: GPL-3.0-or-later
 // SPDX-FileType: SOURCE
 
@@ -163,5 +163,43 @@ public static CryptoGroup<BigInteger, CurvePoint> CreateCryptoGroup(CurveParamet
         {
             return new CryptoGroup<BigInteger, CurvePoint>(new CurveGroupAlgebra(parameters));
         }
+
+        /// <summary>
+        /// Creates a <see cref="CryptoGroup{BigInteger, CurvePoint}" /> instance at least satisfying a given security level.
+        /// </summary>
+        /// <param name="securityLevel">The minimal security level for the curve to be created.</param>
+        public static CryptoGroup<BigInteger, CurvePoint> CreateCryptoGroup(int securityLevel)
+        {
+            CurveParameters parameters;
+            if (securityLevel <= 126)
+            {
+                parameters = CurveParameters.Curve25519;
+            }
+            else if (securityLevel <= 128)
+            {
+                parameters = CurveParameters.NISTP256;
+            }
+            else if (securityLevel <= 190)
+            {
+                parameters = CurveParameters.M383;
+            }
+            else if (securityLevel <= 254)
+            {
+                parameters = CurveParameters.M511;
+            }
+            else if (securityLevel <= 260)
+            {
+                parameters = CurveParameters.NISTP521;
+            }
+            else
+            {
+                throw new ArgumentOutOfRangeException(
+                    $"There are no pre-configured curves that satisfy a security level of {securityLevel}.", nameof(securityLevel)
+                );
+            }
+
+            return CreateCryptoGroup(parameters);
+        }
+
     }
 }