83 lines
3.5 KiB
C#
83 lines
3.5 KiB
C#
using System;
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using System.Security.Cryptography;
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using System.Threading;
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using System.Threading.Tasks;
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using Microsoft.IdentityModel.Tokens;
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namespace StellaOps.Cryptography;
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internal sealed class EcdsaSigner : ICryptoSigner
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{
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private static readonly string[] DefaultKeyOps = { "sign", "verify" };
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private readonly CryptoSigningKey signingKey;
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private EcdsaSigner(CryptoSigningKey signingKey)
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=> this.signingKey = signingKey ?? throw new ArgumentNullException(nameof(signingKey));
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public string KeyId => signingKey.Reference.KeyId;
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public string AlgorithmId => signingKey.AlgorithmId;
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public static ICryptoSigner Create(CryptoSigningKey signingKey) => new EcdsaSigner(signingKey);
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public ValueTask<byte[]> SignAsync(ReadOnlyMemory<byte> data, CancellationToken cancellationToken = default)
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{
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cancellationToken.ThrowIfCancellationRequested();
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using var ecdsa = ECDsa.Create(signingKey.PrivateParameters);
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var hashAlgorithm = ResolveHashAlgorithm(signingKey.AlgorithmId);
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var signature = ecdsa.SignData(data.Span, hashAlgorithm);
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return ValueTask.FromResult(signature);
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}
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public ValueTask<bool> VerifyAsync(ReadOnlyMemory<byte> data, ReadOnlyMemory<byte> signature, CancellationToken cancellationToken = default)
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{
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cancellationToken.ThrowIfCancellationRequested();
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using var ecdsa = ECDsa.Create(signingKey.PublicParameters);
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var hashAlgorithm = ResolveHashAlgorithm(signingKey.AlgorithmId);
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var verified = ecdsa.VerifyData(data.Span, signature.Span, hashAlgorithm);
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return ValueTask.FromResult(verified);
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}
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public JsonWebKey ExportPublicJsonWebKey()
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{
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var jwk = new JsonWebKey
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{
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Kid = signingKey.Reference.KeyId,
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Alg = signingKey.AlgorithmId,
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Kty = JsonWebAlgorithmsKeyTypes.EllipticCurve,
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Use = JsonWebKeyUseNames.Sig,
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Crv = ResolveCurve(signingKey.AlgorithmId)
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};
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foreach (var op in DefaultKeyOps)
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{
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jwk.KeyOps.Add(op);
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}
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jwk.X = Base64UrlEncoder.Encode(signingKey.PublicParameters.Q.X ?? Array.Empty<byte>());
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jwk.Y = Base64UrlEncoder.Encode(signingKey.PublicParameters.Q.Y ?? Array.Empty<byte>());
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return jwk;
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}
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private static HashAlgorithmName ResolveHashAlgorithm(string algorithmId) =>
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algorithmId switch
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{
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es256, StringComparison.OrdinalIgnoreCase) => HashAlgorithmName.SHA256,
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es384, StringComparison.OrdinalIgnoreCase) => HashAlgorithmName.SHA384,
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es512, StringComparison.OrdinalIgnoreCase) => HashAlgorithmName.SHA512,
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_ => throw new InvalidOperationException($"Unsupported ECDSA signing algorithm '{algorithmId}'.")
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};
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private static string ResolveCurve(string algorithmId)
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=> algorithmId switch
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{
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es256, StringComparison.OrdinalIgnoreCase) => JsonWebKeyECTypes.P256,
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es384, StringComparison.OrdinalIgnoreCase) => JsonWebKeyECTypes.P384,
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{ } alg when string.Equals(alg, SignatureAlgorithms.Es512, StringComparison.OrdinalIgnoreCase) => JsonWebKeyECTypes.P521,
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_ => throw new InvalidOperationException($"Unsupported ECDSA curve mapping for algorithm '{algorithmId}'.")
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};
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}
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