diff --git a/pgpainless-core/src/test/java/investigations/InvestigateThunderbirdDecryption.java b/pgpainless-core/src/test/java/investigations/InvestigateThunderbirdDecryption.java
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+++ b/pgpainless-core/src/test/java/investigations/InvestigateThunderbirdDecryption.java
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+/*
+ * Copyright 2021 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 investigations;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Date;
+
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
+import org.bouncycastle.openpgp.PGPSecretKeyRing;
+import org.bouncycastle.util.io.Streams;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.algorithm.DocumentSignatureType;
+import org.pgpainless.encryption_signing.EncryptionOptions;
+import org.pgpainless.encryption_signing.EncryptionStream;
+import org.pgpainless.encryption_signing.ProducerOptions;
+import org.pgpainless.encryption_signing.SigningOptions;
+import org.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.util.ArmorUtils;
+
+public class InvestigateThunderbirdDecryption {
+
+    String OUR_KEY = "-----BEGIN PGP PRIVATE KEY BLOCK-----\n" +
+            "Version: PGPainless\n" +
+            "Comment: 47D2 3A5E 1455 1FD2 0599  C1FC B57B 5451 9E2D 8FE4\n" +
+            "Comment: Alice <alice@pgpainless.org>\n" +
+            "\n" +
+            "lFgEYP8FlBYJKwYBBAHaRw8BAQdAeJ7fL4TbpSLUJsxGUFnN5MzDZr3lKoKWEO+z\n" +
+            "hQEFPqcAAP0T8ED8kcch++7UpcN7qZMP4ihbE9Fu9kp/IKOCZDVwGhF+tBxBbGlj\n" +
+            "ZSA8YWxpY2VAcGdwYWlubGVzcy5vcmc+iHgEExYKACAFAmD/BZQCGwEFFgIDAQAE\n" +
+            "CwkIBwUVCgkICwIeAQIZAQAKCRC1e1RRni2P5PYqAQC/r4R4RFfVIOPAc16PiffO\n" +
+            "GDMzRUYAjIyflvOBIEE//QEAsZGQzIstdIp8gY5CF27pbnnSAA/OGPXbDsNArzPN\n" +
+            "tQicXQRg/wWUEgorBgEEAZdVAQUBAQdAFHEP5NzgON0usvHOsTsROojwVTAqgayc\n" +
+            "fdPdb597u3UDAQgHAAD/ShtbTmAyZJDjcEDfUNblOogyWntCEgb18Cs5rRm1+agP\n" +
+            "mIh1BBgWCgAdBQJg/wWUAhsMBRYCAwEABAsJCAcFFQoJCAsCHgEACgkQtXtUUZ4t\n" +
+            "j+SWdwD/cCXm/ufcaIMMOqRw10Lwefc4euOrpFScWA0rUjnK6yEBAMOH1kGHlLbz\n" +
+            "mk6D7RbBDdC3aW4xGRjSYBkyhbuxevsDnFgEYP8FlBYJKwYBBAHaRw8BAQdAmuvN\n" +
+            "FF+pklSxw3+VVqVu2g2ulpJE7HldtU/Jud/jiEgAAP0RPh7QWqm2hhY6vBNr8fhz\n" +
+            "3GBAfZ4A9HxVymuu1M6qMxEdiNUEGBYKAH0FAmD/BZQCGwIFFgIDAQAECwkIBwUV\n" +
+            "CgkICwIeAV8gBBkWCgAGBQJg/wWUAAoJEIYvdZaRbR0mBesA/2dxyf9vfRnyrNcm\n" +
+            "dguMzYe9oLfD2SU2Sa0jXcURQ+A6AP9uYaehPZvEH0kwdeSi60uCOVznCePrY1mK\n" +
+            "M6UEDMPGBwAKCRC1e1RRni2P5J1FAQDhI3tN5C/klh2j8ptQ7ht0LPlbgVU/WmT8\n" +
+            "kqejd80WVgEA4dg7MZTk+uzwOWEGIHyxWXRzma9a5k1kM+uxX3RflQU=\n" +
+            "=IEzi\n" +
+            "-----END PGP PRIVATE KEY BLOCK-----";
+
+    String THEIR_CERT = "-----BEGIN PGP PUBLIC KEY BLOCK-----\n" +
+            "Version: FlowCrypt [BUILD_REPLACEABLE_VERSION] Gmail Encryption\n" +
+            "Comment: Seamlessly send and receive encrypted email\n" +
+            "\n" +
+            "xjMEYL/CRRYJKwYBBAHaRw8BAQdAxaJrnD/gWRGqaAVtQ8R9PI0ZGu/YESJ4\n" +
+            "HsJeeCxUZOvNF0RlbiA8ZGVuQGZsb3djcnlwdC5jb20+wn4EExYKACYFAmC/\n" +
+            "wkUCGwMFFgIDAQAECwkIBwUVCgkICwIeAQIZAQWJAQ/XOQAKCRCGwF2G4DXc\n" +
+            "cttHAP9Axna+jmFhZEajILW7BZ8UJpgz7mCC48RMtRj/pre4nQD/bKJXB+sD\n" +
+            "zti+tRbi7KNncgkSQeau+Vy/ZnpBUUHBWwjOOARgv8JFEgorBgEEAZdVAQUB\n" +
+            "AQdA3dN8Hh18Pqd6OevXWl36y7cM58ZRmUVEEZukXRIholYDAQgHwnUEGBYK\n" +
+            "AB0FAmC/wkUCGwwFFgIDAQAECwkIBwUVCgkICwIeAQAKCRCGwF2G4DXcclpK\n" +
+            "AQC0uUHWUFNao1Fl85+4c8WecGKsGCihNU9H3q+I1gz22gEAtVo1dWnc0t1f\n" +
+            "h1MUYq5FmME+KeFCBZZ9lrMAxRhvigI=\n" +
+            "=+XVJ\n" +
+            "-----END PGP PUBLIC KEY BLOCK-----\n";
+
+    @Test
+    public void generateMessage() throws PGPException, IOException {
+        System.out.println("Decryption Key");
+        System.out.println(OUR_KEY);
+        PGPSecretKeyRing ourKey = PGPainless.readKeyRing().secretKeyRing(OUR_KEY);
+        PGPPublicKeyRing ourCert = PGPainless.extractCertificate(ourKey);
+        PGPPublicKeyRing theirCert = PGPainless.readKeyRing().publicKeyRing(THEIR_CERT);
+
+        System.out.println("Certificate:");
+        System.out.println(ArmorUtils.toAsciiArmoredString(ourCert));
+
+        System.out.println("Crypt-Only:");
+        ProducerOptions producerOptions = ProducerOptions
+                .encrypt(new EncryptionOptions().addRecipient(ourCert).addRecipient(theirCert))
+                .setFileName("msg.txt")
+                .setModificationDate(new Date());
+
+        generateMessage(producerOptions);
+
+        System.out.println("Sign-Crypt:");
+        producerOptions = ProducerOptions
+                .signAndEncrypt(new EncryptionOptions().addRecipient(ourCert).addRecipient(theirCert),
+                        new SigningOptions().addInlineSignature(SecretKeyRingProtector.unprotectedKeys(), ourKey, DocumentSignatureType.BINARY_DOCUMENT))
+                .setFileName("msg.txt")
+                .setModificationDate(new Date());
+
+        generateMessage(producerOptions);
+    }
+
+    private void generateMessage(ProducerOptions producerOptions) throws PGPException, IOException {
+        String data = "Hello World\n";
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        EncryptionStream encryptionStream = PGPainless.encryptAndOrSign()
+                .onOutputStream(out)
+                .withOptions(producerOptions);
+
+        Streams.pipeAll(new ByteArrayInputStream(data.getBytes(StandardCharsets.UTF_8)), encryptionStream);
+        encryptionStream.close();
+
+        System.out.println(out);
+    }
+}