public SshKeyProvider(EncodingWrapper encoding, Base64Wrapper base64, IRsaKeyProvider rsaKeyProvider, IDsaKeyProvider dsaKeyProvider, IEcKeyProvider ecKeyProvider, SecureRandomGenerator randomGenerator)
        {
            this.encoding        = encoding;
            this.base64          = base64;
            this.rsaKeyProvider  = rsaKeyProvider;
            this.dsaKeyProvider  = dsaKeyProvider;
            this.ecKeyProvider   = ecKeyProvider;
            this.randomGenerator = randomGenerator;

            sshSupportedCurves = new []
            {
                new [] { "curve25519" },
                new [] { "P-256", "secp256r1", "prime256v1" },
                new [] { "P-384", "secp384r1" },
                new [] { "P-521", "secp521r1" }
            };

            sshCurveHeaders = new Dictionary <string, string>
            {
                { "curve25519", "ssh-ed25519" },
                { "P-256", "ecdsa-sha2-nistp256" },
                { "P-384", "ecdsa-sha2-nistp384" },
                { "P-521", "ecdsa-sha2-nistp521" }
            };

            sshCurveIdentifiers = new Dictionary <string, string>
            {
                { "curve25519", "ed25519" },
                { "P-256", "nistp256" },
                { "P-384", "nistp384" },
                { "P-521", "nistp521" }
            };
        }
 /// <summary>
 /// 构造一个 <see cref="RsaSigningCredentialsProvider"/>。
 /// </summary>
 /// <param name="rsaKeyProvider">给定的 <see cref="IRsaKeyProvider"/>。</param>
 public RsaSigningCredentialsProvider(IRsaKeyProvider rsaKeyProvider)
 {
     _rsaKeyProvider = rsaKeyProvider;
 }