diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/parsing/KeyRingReader.java b/pgpainless-core/src/main/java/org/pgpainless/key/parsing/KeyRingReader.java
index 573cbda1..6d67793b 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/parsing/KeyRingReader.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/parsing/KeyRingReader.java
@@ -12,6 +12,7 @@ import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPKeyRing;
@@ -41,6 +42,7 @@ public class KeyRingReader {
      * @return key ring
      * @throws IOException in case of an IO error
      */
+    @Nullable
     public PGPKeyRing keyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readKeyRing(inputStream);
@@ -54,6 +56,7 @@ public class KeyRingReader {
      * @return key ring
      * @throws IOException in case of an IO error
      */
+    @Nullable
     public PGPKeyRing keyRing(@Nonnull byte[] bytes)
             throws IOException {
         return keyRing(new ByteArrayInputStream(bytes));
@@ -67,81 +70,97 @@ public class KeyRingReader {
      * @return key ring
      * @throws IOException in case of an IO error
      */
+    @Nullable
     public PGPKeyRing keyRing(@Nonnull String asciiArmored)
             throws IOException {
         return keyRing(asciiArmored.getBytes(UTF8));
     }
 
+    @Nullable
     public PGPPublicKeyRing publicKeyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readPublicKeyRing(inputStream);
     }
 
+    @Nullable
     public PGPPublicKeyRing publicKeyRing(@Nonnull byte[] bytes)
             throws IOException {
         return publicKeyRing(new ByteArrayInputStream(bytes));
     }
 
+    @Nullable
     public PGPPublicKeyRing publicKeyRing(@Nonnull String asciiArmored)
             throws IOException {
         return publicKeyRing(asciiArmored.getBytes(UTF8));
     }
 
+    @Nonnull
     public PGPPublicKeyRingCollection publicKeyRingCollection(@Nonnull InputStream inputStream)
             throws IOException {
         return readPublicKeyRingCollection(inputStream);
     }
 
+    @Nonnull
     public PGPPublicKeyRingCollection publicKeyRingCollection(@Nonnull byte[] bytes)
             throws IOException {
         return publicKeyRingCollection(new ByteArrayInputStream(bytes));
     }
 
+    @Nonnull
     public PGPPublicKeyRingCollection publicKeyRingCollection(@Nonnull String asciiArmored)
-            throws IOException, PGPException {
+            throws IOException {
         return publicKeyRingCollection(asciiArmored.getBytes(UTF8));
     }
 
+    @Nullable
     public PGPSecretKeyRing secretKeyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readSecretKeyRing(inputStream);
     }
 
+    @Nullable
     public PGPSecretKeyRing secretKeyRing(@Nonnull byte[] bytes)
             throws IOException {
         return secretKeyRing(new ByteArrayInputStream(bytes));
     }
 
+    @Nullable
     public PGPSecretKeyRing secretKeyRing(@Nonnull String asciiArmored)
             throws IOException {
         return secretKeyRing(asciiArmored.getBytes(UTF8));
     }
 
+    @Nonnull
     public PGPSecretKeyRingCollection secretKeyRingCollection(@Nonnull InputStream inputStream)
             throws IOException {
         return readSecretKeyRingCollection(inputStream);
     }
 
+    @Nonnull
     public PGPSecretKeyRingCollection secretKeyRingCollection(@Nonnull byte[] bytes)
             throws IOException {
         return secretKeyRingCollection(new ByteArrayInputStream(bytes));
     }
 
+    @Nonnull
     public PGPSecretKeyRingCollection secretKeyRingCollection(@Nonnull String asciiArmored)
             throws IOException {
         return secretKeyRingCollection(asciiArmored.getBytes(UTF8));
     }
 
+    @Nonnull
     public PGPKeyRingCollection keyRingCollection(@Nonnull InputStream inputStream, boolean isSilent)
             throws IOException, PGPException {
         return readKeyRingCollection(inputStream, isSilent);
     }
 
+    @Nonnull
     public PGPKeyRingCollection keyRingCollection(@Nonnull byte[] bytes, boolean isSilent)
             throws IOException, PGPException {
         return keyRingCollection(new ByteArrayInputStream(bytes), isSilent);
     }
 
+    @Nonnull
     public PGPKeyRingCollection keyRingCollection(@Nonnull String asciiArmored, boolean isSilent)
             throws IOException, PGPException {
         return keyRingCollection(asciiArmored.getBytes(UTF8), isSilent);
@@ -157,6 +176,7 @@ public class KeyRingReader {
      * @return key ring
      * @throws IOException in case of an IO error
      */
+    @Nullable
     public static PGPKeyRing readKeyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readKeyRing(inputStream, MAX_ITERATIONS);
@@ -173,6 +193,7 @@ public class KeyRingReader {
      * @return key ring
      * @throws IOException in case of an IO error
      */
+    @Nullable
     public static PGPKeyRing readKeyRing(@Nonnull InputStream inputStream, int maxIterations)
             throws IOException {
         PGPObjectFactory objectFactory = ImplementationFactory.getInstance().getPGPObjectFactory(
@@ -198,6 +219,7 @@ public class KeyRingReader {
         throw new IOException("Loop exceeded max iteration count.");
     }
 
+    @Nullable
     public static PGPPublicKeyRing readPublicKeyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readPublicKeyRing(inputStream, MAX_ITERATIONS);
@@ -214,6 +236,7 @@ public class KeyRingReader {
      *
      * @throws IOException in case of an IO error or exceeding of max iterations
      */
+    @Nullable
     public static PGPPublicKeyRing readPublicKeyRing(@Nonnull InputStream inputStream, int maxIterations)
             throws IOException {
         PGPObjectFactory objectFactory = ImplementationFactory.getInstance().getPGPObjectFactory(
@@ -236,6 +259,7 @@ public class KeyRingReader {
         throw new IOException("Loop exceeded max iteration count.");
     }
 
+    @Nonnull
     public static PGPPublicKeyRingCollection readPublicKeyRingCollection(@Nonnull InputStream inputStream)
             throws IOException {
         return readPublicKeyRingCollection(inputStream, MAX_ITERATIONS);
@@ -252,6 +276,7 @@ public class KeyRingReader {
      *
      * @throws IOException in case of an IO error or exceeding of max iterations
      */
+    @Nonnull
     public static PGPPublicKeyRingCollection readPublicKeyRingCollection(@Nonnull InputStream inputStream, int maxIterations)
             throws IOException {
         PGPObjectFactory objectFactory = ImplementationFactory.getInstance().getPGPObjectFactory(
@@ -283,6 +308,7 @@ public class KeyRingReader {
         throw new IOException("Loop exceeded max iteration count.");
     }
 
+    @Nullable
     public static PGPSecretKeyRing readSecretKeyRing(@Nonnull InputStream inputStream)
             throws IOException {
         return readSecretKeyRing(inputStream, MAX_ITERATIONS);
@@ -299,6 +325,7 @@ public class KeyRingReader {
      *
      * @throws IOException in case of an IO error or exceeding of max iterations
      */
+    @Nullable
     public static PGPSecretKeyRing readSecretKeyRing(@Nonnull InputStream inputStream, int maxIterations)
             throws IOException {
         InputStream decoderStream = ArmorUtils.getDecoderStream(inputStream);
@@ -322,6 +349,7 @@ public class KeyRingReader {
         throw new IOException("Loop exceeded max iteration count.");
     }
 
+    @Nonnull
     public static PGPSecretKeyRingCollection readSecretKeyRingCollection(@Nonnull InputStream inputStream)
             throws IOException {
         return readSecretKeyRingCollection(inputStream, MAX_ITERATIONS);
@@ -338,6 +366,7 @@ public class KeyRingReader {
      *
      * @throws IOException in case of an IO error or exceeding of max iterations
      */
+    @Nonnull
     public static PGPSecretKeyRingCollection readSecretKeyRingCollection(@Nonnull InputStream inputStream,
                                                                          int maxIterations)
             throws IOException {
@@ -370,6 +399,7 @@ public class KeyRingReader {
         throw new IOException("Loop exceeded max iteration count.");
     }
 
+    @Nonnull
     public static PGPKeyRingCollection readKeyRingCollection(@Nonnull InputStream inputStream, boolean isSilent)
             throws IOException, PGPException {
         return new PGPKeyRingCollection(inputStream, isSilent);