diff --git a/pgpainless-core/src/test/java/org/pgpainless/key/modification/RefuseToAddWeakSubkeyTest.java b/pgpainless-core/src/test/java/org/pgpainless/key/modification/RefuseToAddWeakSubkeyTest.java
new file mode 100644
index 00000000..8d459c33
--- /dev/null
+++ b/pgpainless-core/src/test/java/org/pgpainless/key/modification/RefuseToAddWeakSubkeyTest.java
@@ -0,0 +1,87 @@
+// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.modification;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.NoSuchAlgorithmException;
+import java.util.EnumMap;
+import java.util.Map;
+
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPSecretKeyRing;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.algorithm.EncryptionPurpose;
+import org.pgpainless.algorithm.KeyFlag;
+import org.pgpainless.algorithm.PublicKeyAlgorithm;
+import org.pgpainless.key.generation.KeySpec;
+import org.pgpainless.key.generation.type.KeyType;
+import org.pgpainless.key.generation.type.rsa.RsaLength;
+import org.pgpainless.key.modification.secretkeyring.SecretKeyRingEditorInterface;
+import org.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.policy.Policy;
+import org.pgpainless.util.Passphrase;
+
+public class RefuseToAddWeakSubkeyTest {
+
+    @Test
+    public void testEditorRefusesToAddWeakSubkey() throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, IOException {
+        // ensure default policy is set
+        PGPainless.getPolicy().setPublicKeyAlgorithmPolicy(Policy.PublicKeyAlgorithmPolicy.defaultPublicKeyAlgorithmPolicy());
+
+        PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing()
+                .modernKeyRing("Alice", null);
+        SecretKeyRingEditorInterface editor = PGPainless.modifyKeyRing(secretKeys);
+        KeySpec spec = KeySpec.getBuilder(KeyType.RSA(RsaLength._1024), KeyFlag.ENCRYPT_COMMS).build();
+
+        assertThrows(IllegalArgumentException.class, () ->
+                editor.addSubKey(spec, Passphrase.emptyPassphrase(), SecretKeyRingProtector.unprotectedKeys()));
+    }
+
+    @Test
+    public void testEditorAllowsToAddWeakSubkeyIfCompliesToPublicKeyAlgorithmPolicy() throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, IOException {
+        PGPSecretKeyRing secretKeys = PGPainless.generateKeyRing()
+                .modernKeyRing("Alice", null);
+
+        // set weak policy
+        Map<PublicKeyAlgorithm, Integer> minimalBitStrengths = new EnumMap<>(PublicKeyAlgorithm.class);
+        // §5.4.1
+        minimalBitStrengths.put(PublicKeyAlgorithm.RSA_GENERAL, 1024);
+        minimalBitStrengths.put(PublicKeyAlgorithm.RSA_SIGN, 1024);
+        minimalBitStrengths.put(PublicKeyAlgorithm.RSA_ENCRYPT, 1024);
+        // Note: ElGamal is not mentioned in the BSI document.
+        //  We assume that the requirements are similar to other DH algorithms
+        minimalBitStrengths.put(PublicKeyAlgorithm.ELGAMAL_ENCRYPT, 2000);
+        minimalBitStrengths.put(PublicKeyAlgorithm.ELGAMAL_GENERAL, 2000);
+        // §5.4.2
+        minimalBitStrengths.put(PublicKeyAlgorithm.DSA, 2000);
+        // §5.4.3
+        minimalBitStrengths.put(PublicKeyAlgorithm.ECDSA, 250);
+        // Note: EdDSA is not mentioned in the BSI document.
+        //  We assume that the requirements are similar to other EC algorithms.
+        minimalBitStrengths.put(PublicKeyAlgorithm.EDDSA, 250);
+        // §7.2.1
+        minimalBitStrengths.put(PublicKeyAlgorithm.DIFFIE_HELLMAN, 2000);
+        // §7.2.2
+        minimalBitStrengths.put(PublicKeyAlgorithm.ECDH, 250);
+        minimalBitStrengths.put(PublicKeyAlgorithm.EC, 250);
+        PGPainless.getPolicy().setPublicKeyAlgorithmPolicy(new Policy.PublicKeyAlgorithmPolicy(minimalBitStrengths));
+
+        SecretKeyRingEditorInterface editor = PGPainless.modifyKeyRing(secretKeys);
+        KeySpec spec = KeySpec.getBuilder(KeyType.RSA(RsaLength._1024), KeyFlag.ENCRYPT_COMMS).build();
+
+        secretKeys = editor.addSubKey(spec, Passphrase.emptyPassphrase(), SecretKeyRingProtector.unprotectedKeys())
+                .done();
+
+        assertEquals(2, PGPainless.inspectKeyRing(secretKeys).getEncryptionSubkeys(EncryptionPurpose.ANY).size());
+
+        // reset default policy
+        PGPainless.getPolicy().setPublicKeyAlgorithmPolicy(Policy.PublicKeyAlgorithmPolicy.defaultPublicKeyAlgorithmPolicy());
+    }
+}