diff --git a/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt b/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
index f0a7c52..9a31310 100644
--- a/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
+++ b/sop-java/src/main/kotlin/sop/operation/UpdateKey.kt
@@ -19,25 +19,61 @@ interface UpdateKey {
      */
     fun noArmor(): UpdateKey
 
+    /**
+     * Allow key to be used for signing only.
+     * If this option is not present, the operation may add a new, encryption-capable component key.
+     */
     @Throws(SOPGPException.UnsupportedOption::class) fun signingOnly(): UpdateKey
 
+    /**
+     * Do not allow adding new capabilities to the key.
+     * If this option is not present, the operation may add support for new capabilities to the key.
+     */
     @Throws(SOPGPException.UnsupportedOption::class) fun noAddedCapabilities(): UpdateKey
 
+    /**
+     * Provide a passphrase for unlocking the secret key.
+     *
+     * @param password password
+     */
     @Throws(SOPGPException.PasswordNotHumanReadable::class, SOPGPException.UnsupportedOption::class)
     fun withKeyPassword(password: String): UpdateKey =
         withKeyPassword(password.toByteArray(UTF8Util.UTF8))
 
+    /**
+     * Provide a passphrase for unlocking the secret key.
+     *
+     * @param password password
+     */
     @Throws(SOPGPException.PasswordNotHumanReadable::class, SOPGPException.UnsupportedOption::class)
     fun withKeyPassword(password: ByteArray): UpdateKey
 
+    /**
+     * Provide certificates that might contain updated signatures or third-party certifications.
+     * These certificates will be merged into the key.
+     *
+     * @param certs input stream of certificates
+     */
     @Throws(
         SOPGPException.UnsupportedOption::class, SOPGPException.BadData::class, IOException::class)
     fun mergeCerts(certs: InputStream): UpdateKey
 
+    /**
+     * Provide certificates that might contain updated signatures or third-party certifications.
+     * These certificates will be merged into the key.
+     *
+     * @param certs binary certificates
+     */
     @Throws(
         SOPGPException.UnsupportedOption::class, SOPGPException.BadData::class, IOException::class)
     fun mergeCerts(certs: ByteArray): UpdateKey = mergeCerts(certs.inputStream())
 
+    /**
+     * Provide the OpenPGP key to update.
+     *
+     * @param key input stream containing the key
+     * @return handle to acquire the updated OpenPGP key from
+     */
     @Throws(
         SOPGPException.BadData::class,
         IOException::class,
@@ -45,6 +81,12 @@ interface UpdateKey {
         SOPGPException.PrimaryKeyBad::class)
     fun key(key: InputStream): Ready
 
+    /**
+     * Provide the OpenPGP key to update.
+     *
+     * @param key binary OpenPGP key
+     * @return handle to acquire the updated OpenPGP key from
+     */
     @Throws(
         SOPGPException.BadData::class,
         IOException::class,