Fix various checkstyle issues

pgpainless-sop/src/main/java/org/pgpainless/sop/PGPainlessCLI.java

@@ -1,6 +1,27 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop;
 
-import org.pgpainless.sop.commands.*;
+import org.pgpainless.sop.commands.Armor;
+import org.pgpainless.sop.commands.Dearmor;
+import org.pgpainless.sop.commands.ExtractCert;
+import org.pgpainless.sop.commands.GenerateKey;
+import org.pgpainless.sop.commands.Sign;
+import org.pgpainless.sop.commands.Verify;
+import org.pgpainless.sop.commands.Version;
 import picocli.CommandLine;
 
 @CommandLine.Command(
@@ -9,36 +30,17 @@ import picocli.CommandLine;
                 GenerateKey.class,
                 ExtractCert.class,
                 Sign.class,
-                Verify.class
+                Verify.class,
+                Armor.class,
+                Dearmor.class
         }
 )
 public class PGPainlessCLI implements Runnable {
 
     public static void main(String[] args) {
-        interpret(args);
-        // generateKey();
-    }
-
-    public static void interpret(String... args) {
         CommandLine.run(new PGPainlessCLI(), args);
     }
 
-    private static void version() {
-        CommandLine.run(new PGPainlessCLI(), "version");
-    }
-
-    private static void generateKey() {
-        interpret("generate-key", "--armor", "Alice Example <alice@wonderland.lit>");
-    }
-
-    private static void extractCert() {
-        CommandLine.run(new PGPainlessCLI(), "extract-cert");
-    }
-
-    private static void sign() {
-        interpret("sign", "--armor", "--as=text", "alice.sec");
-    }
-
     @Override
     public void run() {
 

pgpainless-sop/src/main/java/org/pgpainless/sop/Print.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop;
 
 import java.io.IOException;
@@ -13,4 +28,16 @@ public class Print {
             return new String(bytes, "UTF-8");
         }
     }
+
+    public static void print_ln(String msg) {
+        // CHECKSTYLE:OFF
+        System.out.println(msg);
+        // CHECKSTYLE:ON
+    }
+
+    public static void err_ln(String msg) {
+        // CHECKSTYLE:OFF
+        System.err.println(msg);
+        // CHECKSTYLE:ON
+    }
 }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/Armor.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.sop.commands;
+
+import org.bouncycastle.bcpg.ArmoredOutputStream;
+import org.bouncycastle.util.io.Streams;
+import picocli.CommandLine;
+
+import java.io.IOException;
+import java.io.PushbackInputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+import static org.pgpainless.sop.Print.err_ln;
+
+@CommandLine.Command(name = "armor", description = "Add ASCII Armor")
+public class Armor implements Runnable {
+
+    private static final byte[] BEGIN_ARMOR = "-----BEGIN PGP".getBytes(StandardCharsets.UTF_8);
+
+    private enum Label {
+        auto,
+        sig,
+        key,
+        cert,
+        message
+    }
+
+    @CommandLine.Option(names = {"--label"}, description = "Label to be used in the header and tail of the armoring.", paramLabel = "{auto|sig|key|cert|message}")
+    Label label;
+
+    @CommandLine.Option(names = {"--allow-nested"}, description = "Allow additional armoring of already armored input")
+    boolean allowNested = false;
+
+    @Override
+    public void run() {
+
+        try (PushbackInputStream pbIn = new PushbackInputStream(System.in); ArmoredOutputStream armoredOutputStream = new ArmoredOutputStream(System.out)) {
+            byte[] start = new byte[14];
+            int read = pbIn.read(start);
+            pbIn.unread(read);
+            if (Arrays.equals(BEGIN_ARMOR, start) && !allowNested) {
+                Streams.pipeAll(pbIn, System.out);
+            } else {
+                Streams.pipeAll(pbIn, armoredOutputStream);
+            }
+        } catch (IOException e) {
+            err_ln("Input data cannot be ASCII armored.");
+            err_ln(e.getMessage());
+            System.exit(1);
+        }
+    }
+}

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/Dearmor.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.sop.commands;
+
+import org.bouncycastle.bcpg.ArmoredInputStream;
+import org.bouncycastle.util.io.Streams;
+import picocli.CommandLine;
+
+import java.io.IOException;
+
+import static org.pgpainless.sop.Print.err_ln;
+
+@CommandLine.Command(name = "dearmor", description = "Remove ASCII Armor")
+public class Dearmor implements Runnable {
+
+    @Override
+    public void run() {
+        try (ArmoredInputStream in = new ArmoredInputStream(System.in, true)) {
+            Streams.pipeAll(in, System.out);
+        } catch (IOException e) {
+            err_ln("Data cannot be dearmored.");
+            err_ln(e.getMessage());
+            System.exit(1);
+        }
+    }
+}

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/ExtractCert.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop.commands;
 
 import java.io.IOException;
@@ -10,6 +25,9 @@ import org.pgpainless.sop.Print;
 import org.pgpainless.util.BCUtil;
 import picocli.CommandLine;
 
+import static org.pgpainless.sop.Print.err_ln;
+import static org.pgpainless.sop.Print.print_ln;
+
 @CommandLine.Command(name = "extract-cert")
 public class ExtractCert implements Runnable {
 
@@ -25,10 +43,10 @@ public class ExtractCert implements Runnable {
             PGPSecretKeyRing secretKeys = PGPainless.readKeyRing().secretKeyRing(System.in);
             PGPPublicKeyRing publicKeys = BCUtil.publicKeyRingFromSecretKeyRing(secretKeys);
 
-            System.out.println(Print.toString(publicKeys.getEncoded(), !noArmor));
+            print_ln(Print.toString(publicKeys.getEncoded(), !noArmor));
         } catch (IOException | PGPException e) {
-            System.err.println("Error extracting certificate from keys;");
+            err_ln("Error extracting certificate from keys;");
-            System.err.println(e.getMessage());
+            err_ln(e.getMessage());
             System.exit(1);
         }
     }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/GenerateKey.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop.commands;
 
 import java.io.IOException;
@@ -8,9 +23,11 @@ import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.pgpainless.PGPainless;
 import org.pgpainless.sop.Print;
-import org.pgpainless.util.ArmorUtils;
 import picocli.CommandLine;
 
+import static org.pgpainless.sop.Print.err_ln;
+import static org.pgpainless.sop.Print.print_ln;
+
 @CommandLine.Command(name = "generate-key")
 public class GenerateKey implements Runnable {
 
@@ -28,11 +45,11 @@ public class GenerateKey implements Runnable {
         try {
             PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing().simpleEcKeyRing(userId);
 
-            System.out.println(Print.toString(secretKeys.getEncoded(), !noArmor));
+            print_ln(Print.toString(secretKeys.getEncoded(), !noArmor));
 
         } catch (InvalidAlgorithmParameterException | NoSuchAlgorithmException | PGPException | IOException e) {
-            System.err.println("Error creating OpenPGP key:");
+            err_ln("Error creating OpenPGP key:");
-            System.err.println(e.getMessage());
+            err_ln(e.getMessage());
             System.exit(1);
         }
     }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/Sign.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop.commands;
 
 import java.io.ByteArrayOutputStream;
@@ -16,6 +31,9 @@ import org.pgpainless.key.protection.UnprotectedKeysProtector;
 import org.pgpainless.sop.Print;
 import picocli.CommandLine;
 
+import static org.pgpainless.sop.Print.err_ln;
+import static org.pgpainless.sop.Print.print_ln;
+
 @CommandLine.Command(name = "sign")
 public class Sign implements Runnable {
 
@@ -30,7 +48,8 @@ public class Sign implements Runnable {
     @CommandLine.Option(names = {"--no-armor"})
     boolean noArmor = false;
 
-    @CommandLine.Option(names = "--as", description = "Defaults to 'binary'. If '--as=text' and the input data is not valid UTF-8, sign fails with return code 53.")
+    @CommandLine.Option(names = "--as", description = "Defaults to 'binary'. If '--as=text' and the input data is not valid UTF-8, sign fails with return code 53.",
+    paramLabel = "{binary|text}")
     Type type;
 
     @CommandLine.Parameters
@@ -42,9 +61,8 @@ public class Sign implements Runnable {
         try {
             secretKeys = PGPainless.readKeyRing().secretKeyRing(new FileInputStream(secretKeyFile));
         } catch (IOException | PGPException e) {
-            System.err.println("Error reading secret key ring.");
+            err_ln("Error reading secret key ring.");
-            System.err.println(e.getMessage());
+            err_ln(e.getMessage());
-
             System.exit(1);
             return;
         }
@@ -64,11 +82,10 @@ public class Sign implements Runnable {
 
             PGPSignature signature = encryptionStream.getResult().getSignatures().iterator().next();
 
-            System.out.println(Print.toString(signature.getEncoded(), !noArmor));
+            print_ln(Print.toString(signature.getEncoded(), !noArmor));
         } catch (PGPException | IOException e) {
-            System.err.println("Error signing data.");
+            err_ln("Error signing data.");
-            System.err.println(e.getMessage());
+            err_ln(e.getMessage());
-
             System.exit(1);
         }
     }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/Verify.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop.commands;
 
 import org.bouncycastle.openpgp.PGPException;
@@ -12,6 +27,7 @@ import picocli.CommandLine;
 
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.text.DateFormat;
@@ -23,9 +39,22 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.TimeZone;
 
+import static org.pgpainless.sop.Print.err_ln;
+import static org.pgpainless.sop.Print.print_ln;
+
 @CommandLine.Command(name = "verify", description = "Verify a detached signature.\nThe signed data is being read from standard input.")
 public class Verify implements Runnable {
 
+    private static final TimeZone tz = TimeZone.getTimeZone("UTC");
+    private static final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm'Z'");
+
+    private static final Date beginningOfTime = new Date(0);
+    private static final Date endOfTime = new Date(8640000000000000L);
+
+    static {
+        df.setTimeZone(tz);
+    }
+
     @CommandLine.Parameters(index = "0", description = "Detached signature")
     File signature;
 
@@ -43,25 +72,19 @@ public class Verify implements Runnable {
             "Accepts special value \"-\" for end of time.")
     String notAfter = "now";
 
-    private final TimeZone tz = TimeZone.getTimeZone("UTC");
-    private final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm'Z'");
-
-    private final Date beginningOfTime = new Date(0);
-    private final Date endOfTime = new Date(8640000000000000L);
-
     @Override
     public void run() {
-        df.setTimeZone(tz);
         Date notBeforeDate = parseNotBefore();
         Date notAfterDate = parseNotAfter();
 
         Map<File, PGPPublicKeyRing> publicKeys = readCertificatesFromFiles();
         if (publicKeys.isEmpty()) {
-            System.out.println("No certificates supplied.");
+            err_ln("No certificates supplied.");
             System.exit(19);
         }
 
-        try(FileInputStream sigIn = new FileInputStream(signature)) {
+        OpenPgpMetadata metadata;
+        try (FileInputStream sigIn = new FileInputStream(signature)) {
             DecryptionStream verifier = PGPainless.decryptAndOrVerify()
                     .onInputStream(System.in)
                     .doNotDecrypt()
@@ -74,7 +97,18 @@ public class Verify implements Runnable {
             Streams.pipeAll(verifier, out);
             verifier.close();
 
-            OpenPgpMetadata metadata = verifier.getResult();
+            metadata = verifier.getResult();
+        } catch (FileNotFoundException e) {
+            err_ln("Signature file not found:");
+            err_ln(e.getMessage());
+            System.exit(1);
+            return;
+        } catch (IOException | PGPException e) {
+            err_ln("Signature validation failed.");
+            err_ln(e.getMessage());
+            System.exit(1);
+            return;
+        }
 
         Map<OpenPgpV4Fingerprint, PGPSignature> signaturesInTimeRange = new HashMap<>();
         for (OpenPgpV4Fingerprint fingerprint : metadata.getVerifiedSignatures().keySet()) {
@@ -86,14 +120,11 @@ public class Verify implements Runnable {
         }
 
         if (signaturesInTimeRange.isEmpty()) {
-                System.out.println("Signature validation failed.");
+            err_ln("No valid signatures found.");
             System.exit(3);
         }
 
         printValidSignatures(signaturesInTimeRange, publicKeys);
-        } catch (IOException | PGPException e) {
-            e.printStackTrace();
-        }
     }
 
     private void printValidSignatures(Map<OpenPgpV4Fingerprint, PGPSignature> validSignatures, Map<File, PGPPublicKeyRing> publicKeys) {
@@ -108,7 +139,7 @@ public class Verify implements Runnable {
 
                 String utcSigDate = df.format(signature.getCreationTime());
                 OpenPgpV4Fingerprint primaryKeyFp = new OpenPgpV4Fingerprint(publicKeyRing);
-                System.out.println(utcSigDate + " " + sigKeyFp.toString() + " " + primaryKeyFp.toString() +
+                print_ln(utcSigDate + " " + sigKeyFp.toString() + " " + primaryKeyFp.toString() +
                         " signed by " + file.getName());
             }
         }
@@ -117,10 +148,11 @@ public class Verify implements Runnable {
     private Map<File, PGPPublicKeyRing> readCertificatesFromFiles() {
         Map<File, PGPPublicKeyRing> publicKeys = new HashMap<>();
         for (File cert : certificates) {
-            try(FileInputStream in = new FileInputStream(cert)) {
+            try (FileInputStream in = new FileInputStream(cert)) {
                 publicKeys.put(cert, PGPainless.readKeyRing().publicKeyRing(in));
             } catch (IOException e) {
-                e.printStackTrace();
+                err_ln("Cannot read certificate from file " + cert.getAbsolutePath() + ":");
+                err_ln(e.getMessage());
             }
         }
         return publicKeys;
@@ -130,7 +162,7 @@ public class Verify implements Runnable {
         try {
             return notAfter.equals("now") ? new Date() : notAfter.equals("-") ? endOfTime : df.parse(notAfter);
         } catch (ParseException e) {
-            System.out.println("Invalid date string supplied as value of --not-after.");
+            err_ln("Invalid date string supplied as value of --not-after.");
             System.exit(1);
             return null;
         }
@@ -138,9 +170,9 @@ public class Verify implements Runnable {
 
     private Date parseNotBefore() {
         try {
-            return notBefore.equals("now") ? new Date() : notBefore.equals("-") ? beginningOfTime: df.parse(notBefore);
+            return notBefore.equals("now") ? new Date() : notBefore.equals("-") ? beginningOfTime : df.parse(notBefore);
         } catch (ParseException e) {
-            System.out.println("Invalid date string supplied as value of --not-before.");
+            err_ln("Invalid date string supplied as value of --not-before.");
             System.exit(1);
             return null;
         }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/Version.java

@@ -1,12 +1,29 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.pgpainless.sop.commands;
 
 import picocli.CommandLine;
 
+import static org.pgpainless.sop.Print.print_ln;
+
 @CommandLine.Command(name = "version", description = "Display version information about the tool")
 public class Version implements Runnable {
 
     @Override
     public void run() {
-        System.out.println("PGPainless CLI version 0.0.1");
+        print_ln("PGPainless CLI version 0.0.1");
     }
 }

pgpainless-sop/src/main/java/org/pgpainless/sop/commands/package-info.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Subcommands of the PGPainless SOP.
+ */
+package org.pgpainless.sop.commands;

pgpainless-sop/src/main/java/org/pgpainless/sop/package-info.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * PGPainless SOP implementing a Stateless OpenPGP Command Line Interface.
+ * @see <a href="https://tools.ietf.org/html/draft-dkg-openpgp-stateless-cli-01">
+ *     Stateless OpenPGP Command Line Interface
+ *     draft-dkg-openpgp-stateless-cli-01</a>
+ */
+package org.pgpainless.sop;