OpenPGPKeyGenerator: Add factory methods for OpenPGP keys based on RSA

pg/src/main/java/org/bouncycastle/openpgp/api/OpenPGPKeyGenerator.java

@@ -235,13 +235,99 @@ public WithPrimaryKey signOnlyKey()
                 @Override
                 public PGPSignatureSubpacketGenerator apply(PGPSignatureSubpacketGenerator subpackets)
                 {
-                    subpackets.removePacketsOfType(SignatureSubpacketTags.KEY_FLAGS);
                     subpackets.setKeyFlags(true, KeyFlags.CERTIFY_OTHER | KeyFlags.SIGN_DATA);
                     return subpackets;
                 }
             }));
     }
 
+    /**
+     * Generate an OpenPGP key based on a single, multipurpose RSA key of the given strength.
+     * The key will carry a direct-key signature containing default preferences and flags.
+     * If the passed in userId is non-null, it will be added to the key.
+     *
+     * @param bitStrength strength of the RSA key in bits (recommended values: 3072 and above).
+     * @param userId optional user-id
+     * @return builder
+     * @throws PGPException if the key cannot be generated.
+     */
+    public WithPrimaryKey singletonRSAKey(int bitStrength, String userId)
+            throws PGPException
+    {
+        WithPrimaryKey builder = withPrimaryKey(
+                new KeyPairGeneratorCallback()
+                {
+                    @Override
+                    public PGPKeyPair generateFrom(PGPKeyPairGenerator generator)
+                            throws PGPException
+                    {
+                        return generator.generateRsaKeyPair(bitStrength);
+                    }
+                },
+                SignatureParameters.Callback.Util.modifyHashedSubpackets(
+                        new SignatureSubpacketsFunction()
+                        {
+                            @Override
+                            public PGPSignatureSubpacketGenerator apply(PGPSignatureSubpacketGenerator subpackets)
+                            {
+                                subpackets.removePacketsOfType(SignatureSubpacketTags.KEY_FLAGS);
+                                subpackets.setKeyFlags(KeyFlags.CERTIFY_OTHER
+                                        | KeyFlags.SIGN_DATA
+                                        | KeyFlags.ENCRYPT_STORAGE
+                                        | KeyFlags.ENCRYPT_COMMS);
+                                return subpackets;
+                            }
+                        }
+                )
+        );
+
+        if (userId != null)
+        {
+            builder.addUserId(userId);
+        }
+
+        return builder;
+    }
+
+    /**
+     * Generate an OpenPGP key composed of 3 individual component keys based on RSA of the given strength in bits.
+     * The primary key will be used to certify third-party keys.
+     * A subkey is used for signing and a third subkey is used for encryption of messages both for storage and
+     * communications.
+     * The primary key will carry a direct-key signature containing default preferences and flags.
+     * The subkeys will be bound with subkey binding signatures.
+     * If the passed in userId is non-null, it will be added to the key.
+     *
+     * @param bitStrength strength of the keys in bits (recommended values: 3072 and above)
+     * @param userId optional user-id
+     * @return builder
+     * @throws PGPException if the key cannot be generated
+     */
+    public WithPrimaryKey compositeRSAKey(int bitStrength, String userId)
+        throws PGPException
+    {
+        KeyPairGeneratorCallback generatorCallback = new KeyPairGeneratorCallback()
+        {
+            @Override
+            public PGPKeyPair generateFrom(PGPKeyPairGenerator generator)
+                    throws PGPException
+            {
+                return generator.generateRsaKeyPair(bitStrength);
+            }
+        };
+
+        WithPrimaryKey builder = withPrimaryKey(generatorCallback)
+                .addSigningSubkey(generatorCallback)
+                .addEncryptionSubkey(generatorCallback);
+
+        if (userId != null)
+        {
+            builder.addUserId(userId);
+        }
+
+        return builder;
+    }
+
     /**
      * Generate an OpenPGP key with a certification-capable primary key.
      * See {@link PGPKeyPairGenerator#generatePrimaryKey()} for the primary key type

pg/src/test/java/org/bouncycastle/openpgp/api/test/OpenPGPV6KeyGeneratorTest.java

@@ -60,6 +60,9 @@ protected void performTestWith(OpenPGPApi api)
         testGenerateEd25519x25519Key(api);
         testGenerateEd448x448Key(api);
 
+        testGenerateSingletonRSAKey(api);
+        testGenerateCompositeRSAKey(api);
+
         testEnforcesPrimaryOrSubkeyType(api);
         testGenerateKeyWithoutSignatures(api);
     }
@@ -320,6 +323,59 @@ private void testGenerateEd448x448Key(OpenPGPApi api)
         isEquals(KeyFlags.ENCRYPT_COMMS | KeyFlags.ENCRYPT_STORAGE, hashedSubpackets.getKeyFlags());
     }
 
+    private void testGenerateSingletonRSAKey(OpenPGPApi api)
+            throws PGPException
+    {
+        Date creationTime = currentTimeRounded();
+        OpenPGPKeyGenerator generator = api.generateKey(creationTime, false);
+
+        OpenPGPKey key = generator.singletonRSAKey(4096, "Alice <alice@example.com>")
+                .build();
+
+        isEquals("Singleton RSA key MUST consist of only a single primary key.", 1, key.getKeys().size());
+        OpenPGPCertificate.OpenPGPComponentKey primaryKey = key.getPrimaryKey();
+        isEquals("Primary key MUST be an RSA key", PublicKeyAlgorithmTags.RSA_GENERAL, primaryKey.getAlgorithm());
+        isEquals("Primary key MUST have a strength of 4096 bits.", 4096, primaryKey.getPGPPublicKey().getBitStrength());
+
+        isEquals("The primary key MUST be the certification key", primaryKey, key.getCertificationKeys().get(0));
+        isEquals("The primary key MUST be the encryption key", primaryKey, key.getEncryptionKeys().get(0));
+        isEquals("The primary key MUST be the signing key", primaryKey, key.getSigningKeys().get(0));
+
+        isNotNull(key.getUserId("Alice <alice@example.com>"));
+    }
+
+    private void testGenerateCompositeRSAKey(OpenPGPApi api)
+        throws PGPException
+    {
+        Date creationTime = currentTimeRounded();
+        OpenPGPKeyGenerator generator = api.generateKey(creationTime, false);
+
+        OpenPGPKey key = generator.compositeRSAKey(4096, "Alice <alice@example.com>")
+                .build();
+
+        isEquals("The composite RSA key MUST consist of 3 component keys", 3, key.getKeys().size());
+
+        OpenPGPCertificate.OpenPGPComponentKey primaryKey = key.getPrimaryKey();
+        isEquals("Primary key MUST be an RSA key", PublicKeyAlgorithmTags.RSA_GENERAL, primaryKey.getAlgorithm());
+        isEquals("Primary key MUST have a strength of 4096 bits.", 4096, primaryKey.getPGPPublicKey().getBitStrength());
+        isEquals("There MUST be only one certification key", 1, key.getCertificationKeys().size());
+        isEquals("The primary key MUST be the certification key", primaryKey, key.getCertificationKeys().get(0));
+
+        isEquals("There MUST be only one signing key", 1, key.getSigningKeys().size());
+        OpenPGPCertificate.OpenPGPComponentKey signingKey = key.getSigningKeys().get(0);
+        isEquals("Signing key MUST be an RSA key", PublicKeyAlgorithmTags.RSA_GENERAL, signingKey.getAlgorithm());
+        isEquals("Signing key MUST have a strength of 4096 bits.", 4096, signingKey.getPGPPublicKey().getBitStrength());
+        isFalse("The signing key MUST NOT be the primary key", primaryKey.equals(signingKey));
+
+        isEquals("There MUST be only one encryption key", 1, key.getEncryptionKeys().size());
+        OpenPGPCertificate.OpenPGPComponentKey encryptionKey = key.getEncryptionKeys().get(0);
+        isEquals("Primary key MUST be an RSA key", PublicKeyAlgorithmTags.RSA_GENERAL, encryptionKey.getAlgorithm());
+        isEquals("Encryption key MUST have a strength of 4096 bits.", 4096, encryptionKey.getPGPPublicKey().getBitStrength());
+        isFalse("The encryption key MUST NOT be the primary key", primaryKey.equals(encryptionKey));
+
+        isFalse("The signing key MUST NOT be the encryption key", signingKey.equals(encryptionKey));
+    }
+
     private void testGenerateCustomKey(OpenPGPApi api)
         throws PGPException
     {