IdentityShroud/IdentityShroud.Core/Security/Keys/Rsa/RsaProvider.cs

using System.Buffers.Text;
using System.Security.Cryptography;
using IdentityShroud.Core.Messages;

namespace IdentityShroud.Core.Security.Keys.Rsa;

public class RsaKeyPolicy : KeyPolicy
{
    public override string KeyType => "RSA";
    public int KeySize { get; } = 2048;
}

public class RsaProvider : IKeyProvider
{
    public byte[] CreateKey(KeyPolicy policy)
    {
        if (policy is RsaKeyPolicy p)
        {
            using var rsa = RSA.Create(p.KeySize);
            return rsa.ExportPkcs8PrivateKey();
        }

        throw new ArgumentException("Incorrect policy type", nameof(policy));
    }

    public void SetJwkParameters(byte[] key, JsonWebKey jwk)
    {
        using var rsa = RSA.Create();
        rsa.ImportPkcs8PrivateKey(key, out _);
        var parameters = rsa.ExportParameters(includePrivateParameters: false);

        jwk.Exponent = Base64Url.EncodeToString(parameters.Exponent);
        jwk.Modulus = Base64Url.EncodeToString(parameters.Modulus);
    }
}