diff --git a/xmss_core.h b/xmss_core.h
index 3308cae..e670dd8 100644
--- a/xmss_core.h
+++ b/xmss_core.h
@@ -3,45 +3,56 @@
 
 #include "params.h"
 
-/**
+/*
  * Generates a XMSS key pair for a given parameter set.
- * Format sk: [(32bit) idx || SK_SEED || SK_PRF || PUB_SEED || root]
- * Format pk: [root || PUB_SEED] omitting algo oid.
+ * Format sk: [(32bit) index || SK_SEED || SK_PRF || PUB_SEED || root]
+ * Format pk: [root || PUB_SEED], omitting algorithm OID.
  */
-int xmss_core_keypair(const xmss_params *params, unsigned char *pk, unsigned char *sk);
+int xmss_core_keypair(const xmss_params *params,
+                      unsigned char *pk, unsigned char *sk);
+
 /**
- * Signs a message.
- * Returns
- * 1. an array containing the signature followed by the message AND
- * 2. an updated secret key!
+ * Signs a message. Returns an array containing the signature followed by the
+ * message and an updated secret key.
  */
-int xmss_core_sign(const xmss_params *params, unsigned char *sk, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen);
+int xmss_core_sign(const xmss_params *params,
+                   unsigned char *sk,
+                   unsigned char *sm, unsigned long long *smlen,
+                   const unsigned char *m, unsigned long long mlen);
+
 /**
  * Verifies a given message signature pair under a given public key.
- *
- * Note: msg and msglen are pure outputs which carry the message in case
- * verification succeeds. The (input) message is assumed to be within sig_msg
- * which has the form (sig||msg).
+ * Note that this assumes a pk without an OID, i.e. [root || PUB_SEED]
  */
-int xmss_core_sign_open(const xmss_params *params, unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk);
+int xmss_core_sign_open(const xmss_params *params,
+                        unsigned char *m, unsigned long long *mlen,
+                        const unsigned char *sm, unsigned long long smlen,
+                        const unsigned char *pk);
 
 /*
  * Generates a XMSSMT key pair for a given parameter set.
- * Format sk: [(ceil(h/8) bit) idx || SK_SEED || SK_PRF || PUB_SEED || root]
- * Format pk: [root || PUB_SEED] omitting algo oid.
+ * Format sk: [(ceil(h/8) bit) index || SK_SEED || SK_PRF || PUB_SEED]
+ * Format pk: [root || PUB_SEED] omitting algorithm OID.
  */
-int xmssmt_core_keypair(const xmss_params *params, unsigned char *pk, unsigned char *sk);
+int xmssmt_core_keypair(const xmss_params *params,
+                        unsigned char *pk, unsigned char *sk);
+
 /**
- * Signs a message.
- * Returns
- * 1. an array containing the signature followed by the message AND
- * 2. an updated secret key!
- *
+ * Signs a message. Returns an array containing the signature followed by the
+ * message and an updated secret key.
  */
-int xmssmt_core_sign(const xmss_params *params, unsigned char *sk, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen);
+int xmssmt_core_sign(const xmss_params *params,
+                     unsigned char *sk,
+                     unsigned char *sm, unsigned long long *smlen,
+                     const unsigned char *m, unsigned long long mlen);
+
 /**
  * Verifies a given message signature pair under a given public key.
+ * Note that this assumes a pk without an OID, i.e. [root || PUB_SEED]
  */
-int xmssmt_core_sign_open(const xmss_params *params, unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk);
-#endif
+int xmssmt_core_sign_open(const xmss_params *params,
+                          unsigned char *m, unsigned long long *mlen,
+                          const unsigned char *sm, unsigned long long smlen,
+                          const unsigned char *pk);
 
+#endif