Allow some parameters to be NULL if the length is 0.
This change permits users of the ChaCha20/Poly1305 algorithms
(and the AEAD construction thereof) to pass NULL pointers for
data that they do not need, and avoids the need to provide a valid
buffer for data that is not used.
diff --git a/include/mbedtls/aead_chacha20_poly1305.h b/include/mbedtls/aead_chacha20_poly1305.h
index a1ccf31..6c8e420 100644
--- a/include/mbedtls/aead_chacha20_poly1305.h
+++ b/include/mbedtls/aead_chacha20_poly1305.h
@@ -124,6 +124,7 @@
* \param aad_len The length (in bytes) of the AAD. The length has no
* restrictions.
* \param aad Buffer containing the AAD.
+ * This pointer can be NULL if aad_len == 0.
*
* \return MBEDTLS_ERR_AEAD_CHACHA20_POLY1305_BAD_INPUT_DATA is returned
* if \p ctx or \p aad are NULL.
@@ -151,7 +152,9 @@
* \param ctx The ChaCha20-Poly1305 context.
* \param len The length (in bytes) of the data to encrypt or decrypt.
* \param input Buffer containing the data to encrypt or decrypt.
+ * This pointer can be NULL if len == 0.
* \param output Buffer to where the encrypted or decrypted data is written.
+ * This pointer can be NULL if len == 0.
*
* \return MBEDTLS_ERR_AEAD_CHACHA20_POLY1305_BAD_INPUT_DATA is returned
* if \p ctx, \p input, or \p output are NULL.
@@ -195,9 +198,12 @@
* parameter does not matter.
* \param aad_len The length (in bytes) of the AAD data to process.
* \param aad Buffer containing the additional authenticated data (AAD).
+ * This pointer can be NULL if aad_len == 0.
* \param ilen The length (in bytes) of the data to encrypt or decrypt.
* \param input Buffer containing the data to encrypt or decrypt.
+ * This pointer can be NULL if ilen == 0.
* \param output Buffer to where the encrypted or decrypted data is written.
+ * This pointer can be NULL if ilen == 0.
* \param mac Buffer to where the computed 128-bit (16 bytes) MAC is written.
*
* \return MBEDTLS_ERR_AEAD_CHACHA20_POLY1305_BAD_INPUT_DATA is returned