1 files changed, 85 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/util/SubjectPublicKeyInfoFactory.java b/core/src/main/java/org/spongycastle/crypto/util/SubjectPublicKeyInfoFactory.java
new file mode 100644
index 00000000..749de7f3
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+++ b/core/src/main/java/org/spongycastle/crypto/util/SubjectPublicKeyInfoFactory.java
@@ -0,0 +1,85 @@
+package org.spongycastle.crypto.util;
+
+import java.io.IOException;
+
+import org.spongycastle.asn1.ASN1Encodable;
+import org.spongycastle.asn1.ASN1Integer;
+import org.spongycastle.asn1.ASN1OctetString;
+import org.spongycastle.asn1.DERNull;
+import org.spongycastle.asn1.pkcs.PKCSObjectIdentifiers;
+import org.spongycastle.asn1.pkcs.RSAPublicKey;
+import org.spongycastle.asn1.x509.AlgorithmIdentifier;
+import org.spongycastle.asn1.x509.SubjectPublicKeyInfo;
+import org.spongycastle.asn1.x9.X962Parameters;
+import org.spongycastle.asn1.x9.X9ECParameters;
+import org.spongycastle.asn1.x9.X9ECPoint;
+import org.spongycastle.asn1.x9.X9ObjectIdentifiers;
+import org.spongycastle.crypto.params.AsymmetricKeyParameter;
+import org.spongycastle.crypto.params.DSAPublicKeyParameters;
+import org.spongycastle.crypto.params.ECDomainParameters;
+import org.spongycastle.crypto.params.ECNamedDomainParameters;
+import org.spongycastle.crypto.params.ECPublicKeyParameters;
+import org.spongycastle.crypto.params.RSAKeyParameters;
+
+/**
+ * Factory to create ASN.1 subject public key info objects from lightweight public keys.
+ */
+public class SubjectPublicKeyInfoFactory
+{
+    /**
+     * Create a SubjectPublicKeyInfo public key.
+     *
+     * @param publicKey the SubjectPublicKeyInfo encoding
+     * @return the appropriate key parameter
+     * @throws java.io.IOException on an error encoding the key
+     */
+    public static SubjectPublicKeyInfo createSubjectPublicKeyInfo(AsymmetricKeyParameter publicKey) throws IOException
+    {
+        if (publicKey instanceof RSAKeyParameters)
+        {
+            RSAKeyParameters pub = (RSAKeyParameters)publicKey;
+
+            return new SubjectPublicKeyInfo(new AlgorithmIdentifier(PKCSObjectIdentifiers.rsaEncryption, DERNull.INSTANCE), new RSAPublicKey(pub.getModulus(), pub.getExponent()));
+        }
+        else if (publicKey instanceof DSAPublicKeyParameters)
+        {
+            DSAPublicKeyParameters pub = (DSAPublicKeyParameters)publicKey;
+
+            return new SubjectPublicKeyInfo(new AlgorithmIdentifier(X9ObjectIdentifiers.id_dsa), new ASN1Integer(pub.getY()));
+        }
+        else if (publicKey instanceof ECPublicKeyParameters)
+        {
+            ECPublicKeyParameters pub = (ECPublicKeyParameters)publicKey;
+            ECDomainParameters domainParams = pub.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);
+            }
+
+            ASN1OctetString p = (ASN1OctetString)new X9ECPoint(pub.getQ()).toASN1Primitive();
+
+            return new SubjectPublicKeyInfo(new AlgorithmIdentifier(X9ObjectIdentifiers.id_ecPublicKey, params), p.getOctets());
+        }
+        else
+        {
+            throw new IOException("key parameters not recognised.");
+        }
+    }
+}