High Level OpenPGP v6 Key Generation

pg/src/main/java/org/bouncycastle/bcpg/PublicKeyUtils.java

@@ -0,0 +1,54 @@
+package org.bouncycastle.bcpg;
+
+/**
+ * Utility methods related to OpenPGP public key algorithms.
+ */
+public class PublicKeyUtils
+{
+
+    /**
+     * Return true, if the public key algorithm that corresponds to the given ID is capable of signing.
+     * @param publicKeyAlgorithm public key algorithm id
+     * @return true if algorithm can sign
+     */
+    public static boolean isSigningAlgorithm(int publicKeyAlgorithm)
+    {
+        switch (publicKeyAlgorithm)
+        {
+            case PublicKeyAlgorithmTags.RSA_GENERAL:
+            case PublicKeyAlgorithmTags.RSA_SIGN:
+            case PublicKeyAlgorithmTags.DSA:
+            case PublicKeyAlgorithmTags.ECDSA:
+            case PublicKeyAlgorithmTags.ELGAMAL_GENERAL:
+            case PublicKeyAlgorithmTags.EDDSA_LEGACY:
+            case PublicKeyAlgorithmTags.Ed25519:
+            case PublicKeyAlgorithmTags.Ed448:
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    /**
+     * Return true, if the public key algorithm that corresponds to the given ID is capable of encryption.
+     * @param publicKeyAlgorithm public key algorithm id
+     * @return true if algorithm can encrypt
+     */
+    public static boolean isEncryptionAlgorithm(int publicKeyAlgorithm)
+    {
+        switch (publicKeyAlgorithm)
+        {
+            case PublicKeyAlgorithmTags.RSA_GENERAL:
+            case PublicKeyAlgorithmTags.RSA_ENCRYPT:
+            case PublicKeyAlgorithmTags.ELGAMAL_ENCRYPT:
+            case PublicKeyAlgorithmTags.ECDH:
+            case PublicKeyAlgorithmTags.ELGAMAL_GENERAL:
+            case PublicKeyAlgorithmTags.DIFFIE_HELLMAN:
+            case PublicKeyAlgorithmTags.X25519:
+            case PublicKeyAlgorithmTags.X448:
+                return true;
+            default:
+                return false;
+        }
+    }
+}

pg/src/main/java/org/bouncycastle/openpgp/PGPKeyPair.java

@@ -1,6 +1,8 @@
 package org.bouncycastle.openpgp;
 
 import org.bouncycastle.bcpg.KeyIdentifier;
+import org.bouncycastle.bcpg.PublicSubkeyPacket;
+import org.bouncycastle.openpgp.operator.KeyFingerPrintCalculator;
 
 /**
  * General class to handle JCA key pairs and convert them into OpenPGP ones.
@@ -63,4 +65,22 @@ public PGPPrivateKey getPrivateKey()
     {
         return priv;
     }
+
+    public PGPKeyPair asSubkey(KeyFingerPrintCalculator fingerPrintCalculator)
+            throws PGPException
+    {
+        if (pub.getPublicKeyPacket() instanceof PublicSubkeyPacket)
+        {
+            return this; // is already subkey
+        }
+
+        PublicSubkeyPacket pubSubPkt = new PublicSubkeyPacket(
+                pub.getVersion(),
+                pub.getAlgorithm(),
+                pub.getCreationTime(),
+                pub.getPublicKeyPacket().getKey());
+        return new PGPKeyPair(
+                new PGPPublicKey(pubSubPkt, fingerPrintCalculator),
+                new PGPPrivateKey(pub.getKeyID(), pubSubPkt, priv.getPrivateKeyDataPacket()));
+    }
 }