diff --git a/sop-java/src/main/java/sop/operation/DetachedSign.java b/sop-java/src/main/java/sop/operation/DetachedSign.java
deleted file mode 100644
index 745077d..0000000
--- a/sop-java/src/main/java/sop/operation/DetachedSign.java
+++ /dev/null
@@ -1,61 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
-//
-// SPDX-License-Identifier: Apache-2.0
-
-package sop.operation;
-
-import sop.ReadyWithResult;
-import sop.SigningResult;
-import sop.enums.SignAs;
-import sop.exception.SOPGPException;
-
-import java.io.ByteArrayInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-
-public interface DetachedSign extends AbstractSign<DetachedSign> {
-
-    /**
-     * Sets the signature mode.
-     * Note: This method has to be called before {@link #key(InputStream)} is called.
-     *
-     * @param mode signature mode
-     * @return builder instance
-     *
-     * @throws sop.exception.SOPGPException.UnsupportedOption if this option is not supported
-     */
-    DetachedSign mode(SignAs mode)
-            throws SOPGPException.UnsupportedOption;
-
-    /**
-     * Signs data.
-     *
-     * @param data input stream containing data
-     * @return ready
-     *
-     * @throws IOException in case of an IO error
-     * @throws sop.exception.SOPGPException.KeyIsProtected if at least one signing key cannot be unlocked
-     * @throws sop.exception.SOPGPException.ExpectedText if text data was expected, but binary data was encountered
-     */
-    ReadyWithResult<SigningResult> data(InputStream data)
-            throws IOException,
-            SOPGPException.KeyIsProtected,
-            SOPGPException.ExpectedText;
-
-    /**
-     * Signs data.
-     *
-     * @param data byte array containing data
-     * @return ready
-     *
-     * @throws IOException in case of an IO error
-     * @throws sop.exception.SOPGPException.KeyIsProtected if at least one signing key cannot be unlocked
-     * @throws sop.exception.SOPGPException.ExpectedText if text data was expected, but binary data was encountered
-     */
-    default ReadyWithResult<SigningResult> data(byte[] data)
-            throws IOException,
-            SOPGPException.KeyIsProtected,
-            SOPGPException.ExpectedText {
-        return data(new ByteArrayInputStream(data));
-    }
-}
diff --git a/sop-java/src/main/kotlin/sop/operation/DetachedSign.kt b/sop-java/src/main/kotlin/sop/operation/DetachedSign.kt
new file mode 100644
index 0000000..c0e62dd
--- /dev/null
+++ b/sop-java/src/main/kotlin/sop/operation/DetachedSign.kt
@@ -0,0 +1,50 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop.operation
+
+import java.io.IOException
+import java.io.InputStream
+import sop.ReadyWithResult
+import sop.SigningResult
+import sop.enums.SignAs
+import sop.exception.SOPGPException.*
+
+interface DetachedSign : AbstractSign<DetachedSign> {
+
+    /**
+     * Sets the signature mode. Note: This method has to be called before [key] is called.
+     *
+     * @param mode signature mode
+     * @return builder instance
+     * @throws UnsupportedOption if this option is not supported
+     */
+    @Throws(UnsupportedOption::class) fun mode(mode: SignAs): DetachedSign
+
+    /**
+     * Signs data.
+     *
+     * @param data input stream containing data
+     * @return ready
+     * @throws IOException in case of an IO error
+     * @throws KeyIsProtected if at least one signing key cannot be unlocked
+     * @throws ExpectedText if text data was expected, but binary data was encountered
+     */
+    @Throws(IOException::class, KeyIsProtected::class, ExpectedText::class)
+    fun data(data: InputStream): ReadyWithResult<SigningResult>
+
+    /**
+     * Signs data.
+     *
+     * @param data byte array containing data
+     * @return ready
+     * @throws IOException in case of an IO error
+     * @throws sop.exception.SOPGPException.KeyIsProtected if at least one signing key cannot be
+     *   unlocked
+     * @throws sop.exception.SOPGPException.ExpectedText if text data was expected, but binary data
+     *   was encountered
+     */
+    @Throws(IOException::class, KeyIsProtected::class, ExpectedText::class)
+    fun data(data: ByteArray): ReadyWithResult<SigningResult> = data(data.inputStream())
+}