C# PCL HMACSHAX with BouncyCastle-PCL

我想在可移植的C#类中实现此逻辑：

static JsonWebToken()
        {
            HashAlgorithms = new Dictionary<JwtHashAlgorithm, Func<byte[], byte[], byte[]>>
            {
                { JwtHashAlgorithm.HS256, (key, value) => { using (var sha = new HMACSHA256(key)) { return sha.ComputeHash(value); } } },
                { JwtHashAlgorithm.HS384, (key, value) => { using (var sha = new HMACSHA384(key)) { return sha.ComputeHash(value); } } },
                { JwtHashAlgorithm.HS512, (key, value) => { using (var sha = new HMACSHA512(key)) { return sha.ComputeHash(value); } } }
            };
        }

但是HMACSHA256，HMACSHA384和HMACSHA512在便携式中不存在图书馆。

首先我尝试 https://github.com/AArnott/PCLCrypto但我总是得到：An exception of type 'System.NotImplementedException' occurred in PCLCrypto.dll but was not handled in user code

我

检查了然后的代码，我看到 PCL 的 Crpyto 没有实现，并且总是抛出异常

然后我找到了这个库：https://github.com/onovotny/BouncyCastle-PCL

但是没有如何使用它的文档。有人可以给我一个如何实施的例子

吗

var sha = new HMACSHA256(key)
var sha = new HMACSHA384(key)
var sha = new HMACSHA512(key)

与BouncyCastle-PCL。

public class HmacSha256
    {
        private readonly HMac _hmac;
        public HmacSha256(byte[] key)
        {
            _hmac = new HMac(new Sha256Digest());
            _hmac.Init(new KeyParameter(key));
        }
        public byte[] ComputeHash(byte[] value)
        {
            if (value == null) throw new ArgumentNullException("value");
            byte[] resBuf = new byte[_hmac.GetMacSize()];
            _hmac.BlockUpdate(value, 0, value.Length);
            _hmac.DoFinal(resBuf, 0);
            return resBuf;
        }
    }