1 files changed, 72 insertions, 0 deletions
diff --git a/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dsa/DSAUtil.java b/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dsa/DSAUtil.java
new file mode 100644
index 00000000..ae627195
--- /dev/null
+++ b/prov/src/main/java/org/spongycastle/jcajce/provider/asymmetric/dsa/DSAUtil.java
@@ -0,0 +1,72 @@
+package org.spongycastle.jcajce.provider.asymmetric.dsa;
+
+import java.security.InvalidKeyException;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.interfaces.DSAPrivateKey;
+import java.security.interfaces.DSAPublicKey;
+
+import org.spongycastle.asn1.ASN1ObjectIdentifier;
+import org.spongycastle.asn1.oiw.OIWObjectIdentifiers;
+import org.spongycastle.asn1.x9.X9ObjectIdentifiers;
+import org.spongycastle.crypto.params.AsymmetricKeyParameter;
+import org.spongycastle.crypto.params.DSAParameters;
+import org.spongycastle.crypto.params.DSAPrivateKeyParameters;
+import org.spongycastle.crypto.params.DSAPublicKeyParameters;
+
+/**
+ * utility class for converting jce/jca DSA objects
+ * objects into their org.spongycastle.crypto counterparts.
+ */
+public class DSAUtil
+{
+    public static final ASN1ObjectIdentifier[] dsaOids =
+    {
+        X9ObjectIdentifiers.id_dsa,
+        OIWObjectIdentifiers.dsaWithSHA1
+    };
+
+    public static boolean isDsaOid(
+        ASN1ObjectIdentifier algOid)
+    {
+        for (int i = 0; i != dsaOids.length; i++)
+        {
+            if (algOid.equals(dsaOids[i]))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    static public AsymmetricKeyParameter generatePublicKeyParameter(
+        PublicKey    key)
+        throws InvalidKeyException
+    {
+        if (key instanceof DSAPublicKey)
+        {
+            DSAPublicKey    k = (DSAPublicKey)key;
+
+            return new DSAPublicKeyParameters(k.getY(),
+                new DSAParameters(k.getParams().getP(), k.getParams().getQ(), k.getParams().getG()));
+        }
+
+        throw new InvalidKeyException("can't identify DSA public key: " + key.getClass().getName());
+    }
+
+    static public AsymmetricKeyParameter generatePrivateKeyParameter(
+        PrivateKey    key)
+        throws InvalidKeyException
+    {
+        if (key instanceof DSAPrivateKey)
+        {
+            DSAPrivateKey    k = (DSAPrivateKey)key;
+
+            return new DSAPrivateKeyParameters(k.getX(),
+                new DSAParameters(k.getParams().getP(), k.getParams().getQ(), k.getParams().getG()));
+        }
+                        
+        throw new InvalidKeyException("can't identify DSA private key.");
+    }
+}