diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyInfo.java b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyInfo.java
index 9884f654..01f93d0b 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyInfo.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyInfo.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2021 Paul Schaub.
+ * Copyright 2021 Flowcrypt a.s.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,6 +63,16 @@ public class KeyInfo {
         return secretKey == null || isDecrypted(secretKey);
     }
 
+    /**
+     * Returns indication that a contained secret key has S2K of a type GNU_DUMMY_S2K.
+     *
+     * @return true if secret key has S2K of a type GNU_DUMMY_S2K, false if there is public key only,
+     *         or S2K on the secret key is absent or not of a type GNU_DUMMY_S2K.
+     */
+    public boolean hasGnuDummyS2K() {
+        return secretKey != null && hasGnuDummyS2K(secretKey);
+    }
+
     public static String getCurveName(PGPPublicKey publicKey) {
         PublicKeyAlgorithm algorithm = PublicKeyAlgorithm.fromId(publicKey.getAlgorithm());
         ECPublicBCPGKey key;
@@ -95,7 +106,7 @@ public class KeyInfo {
      * @return true if secret key is encrypted, false otherwise.
      */
     public static boolean isEncrypted(PGPSecretKey secretKey) {
-        return secretKey.getS2KUsage() != 0 && secretKey.getS2K().getType() != S2K.GNU_DUMMY_S2K;
+        return secretKey.getS2KUsage() != 0;
     }
 
     /**
@@ -105,6 +116,17 @@ public class KeyInfo {
      * @return true if secret key is encrypted, false otherwise.
      */
     public static boolean isDecrypted(PGPSecretKey secretKey) {
-        return secretKey.getS2KUsage() == 0 || secretKey.getS2K().getType() == S2K.GNU_DUMMY_S2K;
+        return secretKey.getS2KUsage() == 0;
+    }
+
+    /**
+     * Returns indication that a secret key has S2K of a type GNU_DUMMY_S2K.
+     *
+     * @param secretKey A secret key to examine.
+     * @return true if secret key has S2K of a type GNU_DUMMY_S2K, false otherwise.
+     */
+    public static boolean hasGnuDummyS2K(PGPSecretKey secretKey) {
+        final S2K s2k = secretKey.getS2K();
+        return s2k != null && s2k.getType() == S2K.GNU_DUMMY_S2K;
     }
 }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
index c0ab9759..3788d5af 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/info/KeyRingInfo.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2020 Paul Schaub.
+ * Copyright 2021 Flowcrypt a.s.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -297,16 +298,17 @@ public class KeyRingInfo {
     }
 
     /**
-     * Return true when every secret key on the key ring is not encrypted.
-     * If there is at least one encrypted secret key on the ring, return false.
-     * If the ring is a {@link PGPPublicKeyRing}, return true.
+     * Returns true when every secret key on the key ring is not encrypted.
+     * If there is at least one encrypted secret key on the key ring, returns false.
+     * If the key ring is a {@link PGPPublicKeyRing}, returns true.
+     * Sub-keys with S2K of a type GNU_DUMMY_S2K do not affect the result.
      *
      * @return true if all secret keys are unencrypted.
      */
     public boolean isFullyDecrypted() {
         if (isSecretKey()) {
             for (PGPSecretKey secretKey : getSecretKeys()) {
-                if (KeyInfo.isEncrypted(secretKey)) {
+                if (!KeyInfo.hasGnuDummyS2K(secretKey) && KeyInfo.isEncrypted(secretKey)) {
                     return false;
                 }
             }
@@ -316,15 +318,16 @@ public class KeyRingInfo {
 
     /**
      * Returns true when every secret key on the key ring is encrypted.
-     * If there is at least one not encrypted secret key on the ring, return false.
-     * If the ring is a {@link PGPPublicKeyRing}, return false.
+     * If there is at least one not encrypted secret key on the key ring, returns false.
+     * If the key ring is a {@link PGPPublicKeyRing}, returns false.
+     * Sub-keys with S2K of a type GNU_DUMMY_S2K do not affect a result.
      *
      * @return true if all secret keys are encrypted.
      */
     public boolean isFullyEncrypted() {
         if (isSecretKey()) {
             for (PGPSecretKey secretKey : getSecretKeys()) {
-                if (KeyInfo.isDecrypted(secretKey)) {
+                if (!KeyInfo.hasGnuDummyS2K(secretKey) && KeyInfo.isDecrypted(secretKey)) {
                     return false;
                 }
             }
diff --git a/pgpainless-core/src/test/java/org/pgpainless/key/info/KeyRingInfoTest.java b/pgpainless-core/src/test/java/org/pgpainless/key/info/KeyRingInfoTest.java
index b02b182c..5725bbc2 100644
--- a/pgpainless-core/src/test/java/org/pgpainless/key/info/KeyRingInfoTest.java
+++ b/pgpainless-core/src/test/java/org/pgpainless/key/info/KeyRingInfoTest.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2020 Paul Schaub.
+ * Copyright 2021 Flowcrypt a.s.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.