Minor improvements
diff --git a/include/mbedtls/chacha20.h b/include/mbedtls/chacha20.h
index 14436d6..1c6cde0 100644
--- a/include/mbedtls/chacha20.h
+++ b/include/mbedtls/chacha20.h
@@ -82,7 +82,8 @@
* to \c mbedtls_chacha20_update(), and finally to
* \c mbedtls_chacha20_free().
*
- * \param ctx The ChaCha20 context to initialize. Must not be \c NULL.
+ * \param ctx The ChaCha20 context to initialize.
+ * This must not be \c NULL.
*/
void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx );
@@ -90,7 +91,9 @@
* \brief This function releases and clears the specified ChaCha20 context.
*
* \param ctx The ChaCha20 context to clear. May be \c NULL,
- * in which case this function is a no-op.
+ * in which case this function is a no-op. If it is not
+ * \c NULL, it must point to an initialized context.
+ *
*/
void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx );
@@ -103,7 +106,7 @@
* \c mbedtls_chacha_update().
*
* \param ctx The ChaCha20 context to which the key should be bound.
- * Must be initialized.
+ * It must be initialized.
* \param key The encryption/decryption key. Must be 32 bytes in length.
*
* \return \c 0 on success.
@@ -123,7 +126,7 @@
* messages encrypted with the same nonce and key.
*
* \param ctx The ChaCha20 context to which the nonce should be bound.
- * Must be initialized.
+ * It must be initialized and bound to a key.
* \param nonce The nonce. Must be 12 bytes in size.
* \param counter The initial counter value. This is usually 0.
*
@@ -153,7 +156,7 @@
* key and nonce.
*
* \param ctx The ChaCha20 context to use for encryption or decryption.
- * Must be initialized.
+ * It must be initialized and bound to a key and nonce.
* \param size The length of the input data in bytes.
* \param input The buffer holding the input data.
* This pointer can be \c NULL if `size == 0`.