-void cast5_init(uint8_t* key, uint8_t keylength_b, cast5_ctx_t* s);
-void cast5_enc(void* block, cast5_ctx_t *s);
-void cast5_dec(void* block, cast5_ctx_t *s);
+
+/** \fn void cast5_init(const void* key, uint16_t keylength_b, cast5_ctx_t* s);
+ * \brief generate keyschedule/contex for CAST-5
+ *
+ * This function generates the keyschedule from the supplied key for the
+ * CAST-5 cipher and stores it in a supplied ::cast5_ctx_t context.
+ * \param key pointer to the key
+ * \param keylength_b length of the key in bits (maximum 128 bits)
+ * \param s pointer to the context
+ */
+void cast5_init(const void* key, uint16_t keylength_b, cast5_ctx_t* s);
+
+/** \fn void cast5_enc(void* block, const cast5_ctx_t* s);
+ * \brief encrypt a block with the CAST-5 algorithm
+ *
+ * This function encrypts a block of 64 bits (8 bytes) with the CAST-5 algorithm.
+ * It uses a keyschedule as generated by the
+ * cast5_init(void* key, uint8_t keylength_b, cast5_ctx_t* s) function.
+ * \param block pointer to the block which gets encrypted
+ * \param s pointer to the keyschedule/context
+ */
+void cast5_enc(void* block, const cast5_ctx_t* s);
+
+/** \fn void cast5_dec(void* block, const cast5_ctx_t* s);
+ * \brief decrypt a block with the CAST-5 algorithm
+ *
+ * This function decrypts a block of 64 bits (8 bytes) with the CAST-5 algorithm.
+ * It uses a keyschedule as generated by the
+ * cast5_init(void* key, uint8_t keylength_b, cast5_ctx_t* s) function.
+ * \param block pointer to the block which gets decrypted
+ * \param s pointer to the keyschedule/context
+ */
+void cast5_dec(void* block, const cast5_ctx_t* s);