ciphers: Documented return values of init functions

sys/include/crypto/3des.h

@@ -85,8 +85,8 @@ static const uint32_t bigbyte[24] = {
  * @param   keySize     the size of the key
 
  *
- * @return  Whether initialization was successful. The command may be
- *          unsuccessful if the key size is not valid.
+ * @return  1 if the initialization was successful or 0 in case of an error. 
+ *          The command may be unsuccessful if the key size is not valid.
  */
 int tripledes_init(cipher_context_t *context, const uint8_t* key, uint8_t keySize);
 

sys/include/crypto/aes.h

@@ -80,8 +80,8 @@ typedef struct {
  * @param       keySize   the size of the key
  * @param       key       a pointer to the key
  *
- * @return  Whether initialization was successful. The command may be
- *          unsuccessful if the key size is not valid.
+ * @return  1 if the initialization was successful or 0 in case of an error. 
+ *          The command may be unsuccessful if the key size is not valid.
  */
 int aes_init(cipher_context_t *context, const uint8_t *key, uint8_t keySize);
 

sys/include/crypto/ciphers.h

@@ -126,6 +126,9 @@ typedef struct {
  * @param cipher_id  cipher algorithm id
  * @param key        encryption key to use
  * @param key_size   length of the encryption key
+ *
+ * @return  1 if the initialization was successful or 0 in case of an error. 
+ *          The command may be unsuccessful if the key size is not valid.
  */
 int cipher_init(cipher_t* cipher, cipher_id_t cipher_id, const uint8_t* key,
                 uint8_t key_size);

sys/include/crypto/twofish.h

@@ -222,8 +222,8 @@ typedef struct {
  * @param   key_size    key size in bytes
  * @param   key         pointer to the key
  *
- * @return  Whether initialization was successful. The command may be
- *          unsuccessful if the key size is not valid.
+ * @return  1 if the initialization was successful or 0 in case of an error. 
+ *          The command may be unsuccessful if the key size is not valid.
  */
 int twofish_init(cipher_context_t *context, const uint8_t *key, uint8_t key_size);