/// <summary>
 /// Creates a
 /// <see cref="PrivateKeySignature"/>
 /// instance.
 /// </summary>
 /// <param name="pk">
 /// A
 /// <see cref="Org.BouncyCastle.Crypto.ICipherParameters"/>
 /// object.
 /// </param>
 /// <param name="hashAlgorithm">A hash algorithm (e.g. "SHA-1", "SHA-256",...).</param>
 /// <param name="provider">A security provider (e.g. "BC").</param>
 public PrivateKeySignature(ICipherParameters pk, String hashAlgorithm)
 {
     this.pk             = pk;
     this.hashAlgorithm  = DigestAlgorithms.GetDigest(DigestAlgorithms.GetAllowedDigest(hashAlgorithm));
     encryptionAlgorithm = pk.GetAlgorithm();
     if (encryptionAlgorithm.StartsWith("EC"))
     {
         encryptionAlgorithm = "ECDSA";
     }
 }