1 files changed, 86 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/util/PrivateKeyInfoFactory.java b/core/src/main/java/org/spongycastle/crypto/util/PrivateKeyInfoFactory.java
new file mode 100644
index 00000000..3fa6d2f1
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+++ b/core/src/main/java/org/spongycastle/crypto/util/PrivateKeyInfoFactory.java
@@ -0,0 +1,86 @@
+package org.spongycastle.crypto.util;
+
+import java.io.IOException;
+
+import org.spongycastle.asn1.ASN1Encodable;
+import org.spongycastle.asn1.ASN1Integer;
+import org.spongycastle.asn1.DERNull;
+import org.spongycastle.asn1.pkcs.PKCSObjectIdentifiers;
+import org.spongycastle.asn1.pkcs.PrivateKeyInfo;
+import org.spongycastle.asn1.pkcs.RSAPrivateKey;
+import org.spongycastle.asn1.sec.ECPrivateKey;
+import org.spongycastle.asn1.x509.AlgorithmIdentifier;
+import org.spongycastle.asn1.x509.DSAParameter;
+import org.spongycastle.asn1.x9.X962Parameters;
+import org.spongycastle.asn1.x9.X9ECParameters;
+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.ECDomainParameters;
+import org.spongycastle.crypto.params.ECNamedDomainParameters;
+import org.spongycastle.crypto.params.ECPrivateKeyParameters;
+import org.spongycastle.crypto.params.RSAKeyParameters;
+import org.spongycastle.crypto.params.RSAPrivateCrtKeyParameters;
+
+/**
+ * Factory to create ASN.1 private key info objects from lightweight private keys.
+ */
+public class PrivateKeyInfoFactory
+{
+    /**
+     * Create a PrivateKeyInfo representation of a private key.
+     *
+     * @param privateKey the SubjectPublicKeyInfo encoding
+     * @return the appropriate key parameter
+     * @throws java.io.IOException on an error encoding the key
+     */
+    public static PrivateKeyInfo createPrivateKeyInfo(AsymmetricKeyParameter privateKey) throws IOException
+    {
+        if (privateKey instanceof RSAKeyParameters)
+        {
+            RSAPrivateCrtKeyParameters priv = (RSAPrivateCrtKeyParameters)privateKey;
+
+            return new PrivateKeyInfo(new AlgorithmIdentifier(PKCSObjectIdentifiers.rsaEncryption, DERNull.INSTANCE), new RSAPrivateKey(priv.getModulus(), priv.getPublicExponent(), priv.getExponent(), priv.getP(), priv.getQ(), priv.getDP(), priv.getDQ(), priv.getQInv()));
+        }
+        else if (privateKey instanceof DSAPrivateKeyParameters)
+        {
+            DSAPrivateKeyParameters priv = (DSAPrivateKeyParameters)privateKey;
+            DSAParameters params = priv.getParameters();
+
+            return new PrivateKeyInfo(new AlgorithmIdentifier(X9ObjectIdentifiers.id_dsa, new DSAParameter(params.getP(), params.getQ(), params.getG())), new ASN1Integer(priv.getX()));
+        }
+        else if (privateKey instanceof ECPrivateKeyParameters)
+        {
+            ECPrivateKeyParameters priv = (ECPrivateKeyParameters)privateKey;
+            ECDomainParameters domainParams = priv.getParameters();
+            ASN1Encodable params;
+
+            if (domainParams == null)
+            {
+                params = new X962Parameters(DERNull.INSTANCE);      // Implicitly CA
+            }
+            else if (domainParams instanceof ECNamedDomainParameters)
+            {
+                params = new X962Parameters(((ECNamedDomainParameters)domainParams).getName());
+            }
+            else
+            {
+                X9ECParameters ecP = new X9ECParameters(
+                    domainParams.getCurve(),
+                    domainParams.getG(),
+                    domainParams.getN(),
+                    domainParams.getH(),
+                    domainParams.getSeed());
+
+                params = new X962Parameters(ecP);
+            }
+
+            return new PrivateKeyInfo(new AlgorithmIdentifier(X9ObjectIdentifiers.id_ecPublicKey, params), new ECPrivateKey(priv.getD(), params));
+        }
+        else
+        {
+            throw new IOException("key parameters not recognised.");
+        }
+    }
+}