1 files changed, 145 insertions, 0 deletions
diff --git a/Crypto/src/crypto/signers/DsaDigestSigner.cs b/Crypto/src/crypto/signers/DsaDigestSigner.cs
new file mode 100644
index 000000000..aee713450
--- /dev/null
+++ b/Crypto/src/crypto/signers/DsaDigestSigner.cs
@@ -0,0 +1,145 @@
+using System;
+using System.Collections;
+using System.IO;
+using System.Text;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Crypto.Signers;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Signers
+{
+ public class DsaDigestSigner
+ : ISigner
+ {
+ private readonly IDigest digest;
+ private readonly IDsa dsaSigner;
+ private bool forSigning;
+
+ public DsaDigestSigner(
+ IDsa signer,
+ IDigest digest)
+ {
+ this.digest = digest;
+ this.dsaSigner = signer;
+ }
+
+ public string AlgorithmName
+ {
+ get { return digest.AlgorithmName + "with" + dsaSigner.AlgorithmName; }
+ }
+
+ public void Init(
+ bool forSigning,
+ ICipherParameters parameters)
+ {
+ this.forSigning = forSigning;
+
+ AsymmetricKeyParameter k;
+
+ if (parameters is ParametersWithRandom)
+ {
+ k = (AsymmetricKeyParameter)((ParametersWithRandom)parameters).Parameters;
+ }
+ else
+ {
+ k = (AsymmetricKeyParameter)parameters;
+ }
+
+ if (forSigning && !k.IsPrivate)
+ throw new InvalidKeyException("Signing Requires Private Key.");
+
+ if (!forSigning && k.IsPrivate)
+ throw new InvalidKeyException("Verification Requires Public Key.");
+
+ Reset();
+
+ dsaSigner.Init(forSigning, parameters);
+ }
+
+ /**
+ * update the internal digest with the byte b
+ */
+ public void Update(
+ byte input)
+ {
+ digest.Update(input);
+ }
+
+ /**
+ * update the internal digest with the byte array in
+ */
+ public void BlockUpdate(
+ byte[] input,
+ int inOff,
+ int length)
+ {
+ digest.BlockUpdate(input, inOff, length);
+ }
+
+ /**
+ * Generate a signature for the message we've been loaded with using
+ * the key we were initialised with.
+ */
+ public byte[] GenerateSignature()
+ {
+ if (!forSigning)
+ throw new InvalidOperationException("DSADigestSigner not initialised for signature generation.");
+
+ byte[] hash = new byte[digest.GetDigestSize()];
+ digest.DoFinal(hash, 0);
+
+ BigInteger[] sig = dsaSigner.GenerateSignature(hash);
+
+ return DerEncode(sig[0], sig[1]);
+ }
+
+ /// <returns>true if the internal state represents the signature described in the passed in array.</returns>
+ public bool VerifySignature(
+ byte[] signature)
+ {
+ if (forSigning)
+ throw new InvalidOperationException("DSADigestSigner not initialised for verification");
+
+ byte[] hash = new byte[digest.GetDigestSize()];
+ digest.DoFinal(hash, 0);
+
+ try
+ {
+ BigInteger[] sig = DerDecode(signature);
+ return dsaSigner.VerifySignature(hash, sig[0], sig[1]);
+ }
+ catch (IOException)
+ {
+ return false;
+ }
+ }
+
+ /// <summary>Reset the internal state</summary>
+ public void Reset()
+ {
+ digest.Reset();
+ }
+
+ private byte[] DerEncode(
+ BigInteger r,
+ BigInteger s)
+ {
+ return new DerSequence(new DerInteger(r), new DerInteger(s)).GetDerEncoded();
+ }
+
+ private BigInteger[] DerDecode(
+ byte[] encoding)
+ {
+ Asn1Sequence s = (Asn1Sequence) Asn1Object.FromByteArray(encoding);
+
+ return new BigInteger[]
+ {
+ ((DerInteger) s[0]).Value,
+ ((DerInteger) s[1]).Value
+ };
+ }
+ }
+}
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