diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/RSA.java b/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/RSA.java
deleted file mode 100644
index 3cf717b2..00000000
--- a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/RSA.java
+++ /dev/null
@@ -1,48 +0,0 @@
-// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package org.pgpainless.key.generation.type.rsa;
-
-import javax.annotation.Nonnull;
-import java.security.spec.AlgorithmParameterSpec;
-import java.security.spec.RSAKeyGenParameterSpec;
-
-import org.pgpainless.algorithm.PublicKeyAlgorithm;
-import org.pgpainless.key.generation.type.KeyType;
-
-/**
- * Key type that specifies the RSA_GENERAL algorithm.
- */
-public class RSA implements KeyType {
-
-    private final RsaLength length;
-
-    RSA(@Nonnull RsaLength length) {
-        this.length = length;
-    }
-
-    public static RSA withLength(@Nonnull RsaLength length) {
-        return new RSA(length);
-    }
-
-    @Override
-    public String getName() {
-        return "RSA";
-    }
-
-    @Override
-    public PublicKeyAlgorithm getAlgorithm() {
-        return PublicKeyAlgorithm.RSA_GENERAL;
-    }
-
-    @Override
-    public int getBitStrength() {
-        return length.getLength();
-    }
-
-    @Override
-    public AlgorithmParameterSpec getAlgorithmSpec() {
-        return new RSAKeyGenParameterSpec(length.getLength(), RSAKeyGenParameterSpec.F4);
-    }
-}
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/package-info.java b/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/package-info.java
deleted file mode 100644
index 2a2a0120..00000000
--- a/pgpainless-core/src/main/java/org/pgpainless/key/generation/type/rsa/package-info.java
+++ /dev/null
@@ -1,8 +0,0 @@
-// SPDX-FileCopyrightText: 2020 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-/**
- * Classes related to RSA.
- */
-package org.pgpainless.key.generation.type.rsa;
diff --git a/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/rsa/RSA.kt b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/rsa/RSA.kt
new file mode 100644
index 00000000..1f8c0509
--- /dev/null
+++ b/pgpainless-core/src/main/kotlin/org/pgpainless/key/generation/type/rsa/RSA.kt
@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.key.generation.type.rsa
+
+import org.pgpainless.algorithm.PublicKeyAlgorithm
+import org.pgpainless.key.generation.type.KeyType
+import java.security.spec.RSAKeyGenParameterSpec
+
+/**
+ * Key type that specifies the RSA_GENERAL algorithm.
+ */
+class RSA private constructor(length: RsaLength): KeyType {
+
+    override val name = "RSA"
+    override val algorithm = PublicKeyAlgorithm.RSA_GENERAL
+    override val bitStrength = length.length
+    override val algorithmSpec = RSAKeyGenParameterSpec(length.length, RSAKeyGenParameterSpec.F4)
+
+    companion object {
+        @JvmStatic
+        fun withLength(length: RsaLength) = RSA(length)
+    }
+}
\ No newline at end of file