diff --git a/pgpainless-core/src/test/java/investigations/UnknownKeyVersion.java b/pgpainless-core/src/test/java/investigations/UnknownKeyVersion.java
new file mode 100644
index 00000000..d9976666
--- /dev/null
+++ b/pgpainless-core/src/test/java/investigations/UnknownKeyVersion.java
@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2024 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package investigations;
+
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+
+import java.io.IOException;
+
+public class UnknownKeyVersion {
+
+    @Test
+    public void test() throws IOException {
+        String KEY = "-----BEGIN PGP PUBLIC KEY BLOCK-----\n" +
+                "\n" +
+                "xsDNBF2lnPIBDAC5cL9PQoQLTMuhjbYvb4Ncuuo0bfmgPRFywX53jPhoFf4Zg6mv\n" +
+                "/seOXpgecTdOcVttfzC8ycIKrt3aQTiwOG/ctaR4Bk/t6ayNFfdUNxHWk4WCKzdz\n" +
+                "/56fW2O0F23qIRd8UUJp5IIlN4RDdRCtdhVQIAuzvp2oVy/LaS2kxQoKvph/5pQ/\n" +
+                "5whqsyroEWDJoSV0yOb25B/iwk/pLUFoyhDG9bj0kIzDxrEqW+7Ba8nocQlecMF3\n" +
+                "X5KMN5kp2zraLv9dlBBpWW43XktjcCZgMy20SouraVma8Je/ECwUWYUiAZxLIlMv\n" +
+                "9CurEOtxUw6N3RdOtLmYZS9uEnn5y1UkF88o8Nku890uk6BrewFzJyLAx5wRZ4F0\n" +
+                "qV/yq36UWQ0JB/AUGhHVPdFf6pl6eaxBwT5GXvbBUibtf8YI2og5RsgTWtXfU7eb\n" +
+                "SGXrl5ZMpbA6mbfhd0R8aPxWfmDWiIOhBufhMCvUHh1sApMKVZnvIff9/0Dca3wb\n" +
+                "vLIwa3T4CyshfT0AEQEAAc0hQm9iIEJhYmJhZ2UgPGJvYkBvcGVucGdwLmV4YW1w\n" +
+                "bGU+wsEOBBMBCgA4AhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEE0aZuGiOx\n" +
+                "gsmYD3iM+/zIKgFeczAFAl2lnvoACgkQ+/zIKgFeczBvbAv/VNk90a6hG8Od9xTz\n" +
+                "XxH5YRFUSGfIA1yjPIVOnKqhMwps2U+sWE3urL+MvjyQRlyRV8oY9IOhQ5Esm6DO\n" +
+                "ZYrTnE7qVETm1ajIAP2OFChEc55uH88x/anpPOXOJY7S8jbn3naC9qad75BrZ+3g\n" +
+                "9EBUWiy5p8TykP05WSnSxNRt7vFKLfEB4nGkehpwHXOVF0CRNwYle42bg8lpmdXF\n" +
+                "DcCZCi+qEbafmTQzkAqyzS3nCh3IAqq6Y0kBuaKLm2tSNUOlZbD+OHYQNZ5Jix7c\n" +
+                "ZUzs6Xh4+I55NRWl5smrLq66yOQoFPy9jot/Qxikx/wP3MsAzeGaZSEPc0fHp5G1\n" +
+                "6rlGbxQ3vl8/usUV7W+TMEMljgwd5x8POR6HC8EaCDfVnUBCPi/Gv+egLjsIbPJZ\n" +
+                "ZEroiE40e6/UoCiQtlpQB5exPJYSd1Q1txCwueih99PHepsDhmUQKiACszNU+RRo\n" +
+                "zAYau2VdHqnRJ7QYdxHDiH49jPK4NTMyb/tJh2TiIwcmsIpGzsFKBF2lnPJjCADj\n" +
+                "XcBWoBQPy0vnuVEzre6EXaQJYR2WW7aLr/QwDU0Nwcw9QeAlMfbABIzDy32pXfsD\n" +
+                "gOaMfOODlAYaW7HQ/iJOLHK8l9+UBh8w3p1/aMYAM5kwP/PK5VaOT4zpXTwLoRO2\n" +
+                "IDspzX4GEAsikh5/HA/tINXtoIUr5Kg+S9EsF1JY4KzjamBwYxrAIPWGtkpQilWJ\n" +
+                "LjPsj1Wn08ZOVIaJvRXC8wdFSLw6AzrDGfEWeDkXUJUVDy/vtHL7EZL2FenttRRN\n" +
+                "8CgFoUQnDzY6SYh6L1tnKF8yfKg2O0DjT72TEH+yFXbGzmRpiCAWbTM2558YitFM\n" +
+                "omeu8KeZUCM3dMCYaKZbB/4o/Nl9eDZzWUlHPOpi9UKev5dGgtmopTZUeBSnhLkG\n" +
+                "kOKCEXBBZTLdx3UyEi8QV9XJsYBAWRKa19pS33HwtYgK2TNRe5XroJBoL0sjsUnB\n" +
+                "Jz1r8rnNt5EX5aOBQPZvG+ih5B5TaYffJsZF376wmIDd6M9dThHj9HH8nui2xNEN\n" +
+                "vS5yNksqI8ehIwAj3wwcwqnFkqdliEss7ErYmRlt51fQIs+oCqTFe/YfMkvePW4/\n" +
+                "riluP2sJpxStSpD21C83kN1xpSDx1W0jIulE0+EqGk997wbWAfy6Fv2V+JrzYpej\n" +
+                "Lt7OHgcZDFppjHpDg1VrUj2GWaLt83uYVKLarC3OHnezwsE+BBgBCgByBYJdpZzy\n" +
+                "CRD7/MgqAV5zMEcUAAAAAAAeACBzYWx0QG5vdGF0aW9ucy5zZXF1b2lhLXBncC5v\n" +
+                "cmfXHtuoHICRZCURoCNLw5rdWBodqTTk+2bSlujPHAQ57QKbDBYhBNGmbhojsYLJ\n" +
+                "mA94jPv8yCoBXnMwAADaBwwAj9uyOR7/bNa1x82F8rroudPrR1FS+IWyjyKLKp3u\n" +
+                "tDZZl7gjDQnwp+WH/kXWbA0mgGQIhMw8z2e8CbPpcVufowm0jN4DOZvXwwwVBlSn\n" +
+                "YD0N3blVrVaUMevxaR51mUAODVMrCnzfzxdTS84d9iUnVWPOQupafHmvMHW46rXS\n" +
+                "go7ckWPScA3WonhOvkdcEXWUkotQYR5/xjPUIJk41khrXwJXnaB1Js7GlEPItn0z\n" +
+                "2/buuatcpqrYJiLk4kRV4Cyr4WEJsZ8RXM0yQQM7s9A7uzGMujeSkMsfoMS1+N7b\n" +
+                "SzbqgNppJQt1X1sLjwchxmN0iV72KqeDdUcKASNRKFqN1SG3qgw72RH8RczeToY0\n" +
+                "NEMSqThFpxlmgRw8OPr8BbOqp6YG7NWprJ+53JCsO6fDN7vAEtjEUMVFXIiC0kss\n" +
+                "eU9tP3bmUFMp59f7jamXb6nBvATlT4UXkZb4w/eCIqIhwvCj8LgJvI9w40uFoZxz\n" +
+                "qL69eex25sL6yB33k2aiZQ1f\n" +
+                "=zrVt\n" +
+                "-----END PGP PUBLIC KEY BLOCK-----\n";
+
+        PGPPublicKeyRing cert = PGPainless.readKeyRing().publicKeyRing(KEY);
+    }
+}
diff --git a/pgpainless-core/src/test/java/investigations/V6Key.java b/pgpainless-core/src/test/java/investigations/V6Key.java
new file mode 100644
index 00000000..0bd1b3d3
--- /dev/null
+++ b/pgpainless-core/src/test/java/investigations/V6Key.java
@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2024 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package investigations;
+
+import org.bouncycastle.openpgp.PGPPublicKeyRing;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.key.info.KeyRingInfo;
+
+import java.io.IOException;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class V6Key {
+
+    @Test
+    public void test() throws IOException {
+        String key = "-----BEGIN PGP PUBLIC KEY BLOCK-----\n" +
+                "\n" +
+                "xioGY4d/4xsAAAAg+U2nu0jWCmHlZ3BqZYfQMxmZu52JGggkLq2EVD34laPCsQYf\n" +
+                "GwoAAABCBYJjh3/jAwsJBwUVCg4IDAIWAAKbAwIeCSIhBssYbE8GCaaX5NUt+mxy\n" +
+                "KwwfHifBilZwj2Ul7Ce62azJBScJAgcCAAAAAK0oIBA+LX0ifsDm185Ecds2v8lw\n" +
+                "gyU2kCcUmKfvBXbAf6rhRYWzuQOwEn7E/aLwIwRaLsdry0+VcallHhSu4RN6HWaE\n" +
+                "QsiPlR4zxP/TP7mhfVEe7XWPxtnMUMtf15OyA51YBM4qBmOHf+MZAAAAIIaTJINn\n" +
+                "+eUBXbki+PSAld2nhJh/LVmFsS+60WyvXkQ1wpsGGBsKAAAALAWCY4d/4wKbDCIh\n" +
+                "BssYbE8GCaaX5NUt+mxyKwwfHifBilZwj2Ul7Ce62azJAAAAAAQBIKbpGG2dWTX8\n" +
+                "j+VjFM21J0hqWlEg+bdiojWnKfA5AQpWUWtnNwDEM0g12vYxoWM8Y81W+bHBw805\n" +
+                "I8kWVkXU6vFOi+HWvv/ira7ofJu16NnoUkhclkUrk0mXubZvyl4GBg==\n" +
+                "-----END PGP PUBLIC KEY BLOCK-----";
+        PGPPublicKeyRing cert = PGPainless.readKeyRing().publicKeyRing(key);
+
+        KeyRingInfo info = PGPainless.inspectKeyRing(cert);
+        assertTrue(info.isUsableForEncryption());
+    }
+}
diff --git a/pgpainless-core/src/test/kotlin/org/pgpainless/key/KeyWithUnknownSecretKeyEncryptionMethodTest.kt b/pgpainless-core/src/test/kotlin/org/pgpainless/key/KeyWithUnknownSecretKeyEncryptionMethodTest.kt
index 253c0f19..471101f3 100644
--- a/pgpainless-core/src/test/kotlin/org/pgpainless/key/KeyWithUnknownSecretKeyEncryptionMethodTest.kt
+++ b/pgpainless-core/src/test/kotlin/org/pgpainless/key/KeyWithUnknownSecretKeyEncryptionMethodTest.kt
@@ -29,7 +29,7 @@ DhxJVTgA/1WaFrKdP3AgL0Ffdooc5XXbjQsj0uHo6FZSHRI4pchMAQCyJnKQ3RvW
 -----END PGP PRIVATE KEY BLOCK-----"""
 
     @Test
-    @Disabled("Disabled since BC 1.77 chokes on the test key")
+    // @Disabled("Disabled since BC 1.77 chokes on the test key")
     fun testExtractCertificate() {
         val key = PGPainless.readKeyRing().secretKeyRing(KEY)!!
         val cert = PGPainless.extractCertificate(key)