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Diffstat (limited to 'back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs')
| -rw-r--r-- | back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs b/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs new file mode 100644 index 0000000..2eea450 --- /dev/null +++ b/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs @@ -0,0 +1,209 @@ +// Copyright (C) 2023 Vaughn Nugent +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU Affero General Public License as +// published by the Free Software Foundation, either version 3 of the +// License, or (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Affero General Public License for more details. +// +// You should have received a copy of the GNU Affero General Public License +// along with this program. If not, see <https://www.gnu.org/licenses/>. + +using System; +using System.Runtime.InteropServices; + +using VNLib.Hashing; +using VNLib.Utils; +using VNLib.Utils.Native; +using VNLib.Utils.Extensions; + +namespace NVault.Crypto.Secp256k1 +{ + + public unsafe class LibSecp256k1 : VnDisposeable + { + public const int SecretKeySize = 32; + public const int XOnlyPublicKeySize = 32; + public const int SignatureSize = 64; + public const int KeyPairSize = 96; + public const int RandomBufferSize = 32; + + /* + * Unsafe structures that represent the native keypair and x-only public key + * structures. They hold character arrays + */ + [StructLayout(LayoutKind.Sequential)] + internal struct KeyPair + { + public fixed byte data[Length]; + public const int Length = KeyPairSize; + } + + [StructLayout(LayoutKind.Sequential)] + internal struct XOnlyPubKey + { + public fixed byte data[Length]; + public const int Length = 64; + } + + //Native methods + [SafeMethodName("secp256k1_context_create")] + internal delegate IntPtr CreateContext(int flags); + + [SafeMethodName("secp256k1_context_destroy")] + internal delegate void DestroyContext(IntPtr context); + + [SafeMethodName("secp256k1_context_randomize")] + internal delegate int RandomizeContext(IntPtr context, byte* seed32); + + [SafeMethodName("secp256k1_keypair_create")] + internal delegate int KeypairCreate(IntPtr context, KeyPair* keyPair, byte* secretKey); + + [SafeMethodName("secp256k1_keypair_xonly_pub")] + internal delegate int KeypairXOnlyPub(IntPtr ctx, XOnlyPubKey* pubkey, int pk_parity, KeyPair* keypair); + + [SafeMethodName("secp256k1_xonly_pubkey_serialize")] + internal delegate int XOnlyPubkeySerialize(IntPtr ctx, byte* output32, XOnlyPubKey* pubkey); + + [SafeMethodName("secp256k1_schnorrsig_sign32")] + internal delegate int SignHash(IntPtr ctx, byte* sig64, byte* msg32, KeyPair* keypair, byte* aux_rand32); + + /// <summary> + /// Loads the Secp256k1 library from the specified path and creates a wrapper class (loads methods from the library) + /// </summary> + /// <param name="dllPath">The realtive or absolute path to the shared library</param> + /// <param name="search">The DLL probing path pattern</param> + /// <returns>The <see cref="LibSecp256k1"/> library wrapper class</returns> + /// <exception cref="DllNotFoundException"></exception> + /// <exception cref="ArgumentNullException"></exception> + /// <exception cref="MissingMemberException"></exception> + /// <exception cref="EntryPointNotFoundException"></exception> + public static LibSecp256k1 LoadLibrary(string dllPath, DllImportSearchPath search, IRandomSource? random) + { + _ = dllPath?? throw new ArgumentNullException(nameof(dllPath)); + + //try to load the library + SafeLibraryHandle lib = SafeLibraryHandle.LoadLibrary(dllPath, search); + + //try to create the wrapper class, if it fails, dispose the library + try + { + //setup fallback random source if null + random ??= new FallbackRandom(); + + //Create the lib + return new LibSecp256k1(lib, random); + } + catch + { + //Dispose the library if the creation failed + lib.Dispose(); + throw; + } + } + + /// <summary> + /// The underlying library handle + /// </summary> + public SafeLibraryHandle SafeLibHandle { get; } + + internal readonly KeypairCreate _createKeyPair; + internal readonly CreateContext _create; + internal readonly RandomizeContext _randomize; + internal readonly DestroyContext _destroy; + internal readonly KeypairXOnlyPub _createXonly; + internal readonly XOnlyPubkeySerialize _serializeXonly; + internal readonly SignHash _signHash; + private readonly IRandomSource _randomSource; + + /// <summary> + /// Creates a new instance of the <see cref="LibSecp256k1"/> class from the specified library handle + /// </summary> + /// <param name="handle">The library handle that referrences the secp256k1 platform specific library</param> + /// <remarks> + /// This method attempts to capture all the native methods from the library, which may throw if the library is not valid. + /// </remarks> + /// <exception cref="ArgumentNullException"></exception> + /// <exception cref="MissingMemberException"></exception> + /// <exception cref="EntryPointNotFoundException"></exception> + public LibSecp256k1(SafeLibraryHandle handle, IRandomSource randomSource) + { + //Store library handle + SafeLibHandle = handle ?? throw new ArgumentNullException(nameof(handle)); + + //Get all method handles and store them + _create = handle.DangerousGetMethod<CreateContext>(); + _createKeyPair = handle.DangerousGetMethod<KeypairCreate>(); + _randomize = handle.DangerousGetMethod<RandomizeContext>(); + _destroy = handle.DangerousGetMethod<DestroyContext>(); + _createXonly = handle.DangerousGetMethod<KeypairXOnlyPub>(); + _serializeXonly = handle.DangerousGetMethod<XOnlyPubkeySerialize>(); + _signHash = handle.DangerousGetMethod<SignHash>(); + + //Store random source + _randomSource = randomSource; + } + + /// <summary> + /// Creates a new instance of the <see cref="LibSecp256k1"/> class from the specified library handle + /// with a fallback random source + /// </summary> + /// <param name="handle">The library handle</param> + /// <exception cref="ArgumentNullException"></exception> + /// <exception cref="MissingMemberException"></exception> + /// <exception cref="EntryPointNotFoundException"></exception> + public LibSecp256k1(SafeLibraryHandle handle):this(handle, new FallbackRandom()) + {} + + /// <summary> + /// Generates a new secret key and writes it to the specified buffer. The buffer size must be exactly <see cref="SecretKeySize"/> bytes long + /// </summary> + /// <param name="buffer">The secret key buffer</param> + /// <exception cref="ArgumentException"></exception> + public void CreateSecretKey(Span<byte> buffer) + { + //Protect for released lib + SafeLibHandle.ThrowIfClosed(); + + if(buffer.Length != SecretKeySize) + { + throw new ArgumentException($"Buffer must be exactly {SecretKeySize} bytes long", nameof(buffer)); + } + + //Fill the buffer with random bytes + _randomSource.GetRandomBytes(buffer); + } + + /// <summary> + /// Fills the given buffer with random bytes from + /// the internal random source + /// </summary> + /// <param name="buffer">The buffer to fill with random data</param> + public void GetRandomBytes(Span<byte> buffer) + { + //Protect for released lib + SafeLibHandle.ThrowIfClosed(); + + _randomSource.GetRandomBytes(buffer); + } + + protected override void Free() + { + //Free native library + SafeLibHandle.Dispose(); + } + + private record class FallbackRandom : IRandomSource + { + public void GetRandomBytes(Span<byte> buffer) + { + //Use the random generator from the crypto lib + RandomHash.GetRandomBytes(buffer); + } + } + } +}
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