Merge remote-tracking branch 'public/pr/1671' into mbedtls-2.1
diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index 1b77aae..8b679aa 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -85,19 +85,41 @@
* If buffers overlap, the output buffer must trail at least 8 bytes
* behind the input buffer.
*
- * \param ctx GCM context
- * \param mode MBEDTLS_GCM_ENCRYPT or MBEDTLS_GCM_DECRYPT
- * \param length length of the input data
- * \param iv initialization vector
- * \param iv_len length of IV
- * \param add additional data
- * \param add_len length of additional data
- * \param input buffer holding the input data
- * \param output buffer for holding the output data
- * \param tag_len length of the tag to generate
- * \param tag buffer for holding the tag
+ * \warning When this function performs a decryption, it outputs the
+ * authentication tag and does not verify that the data is
+ * authentic. You should use this function to perform encryption
+ * only. For decryption, use mbedtls_gcm_auth_decrypt() instead.
*
- * \return 0 if successful
+ * \param ctx The GCM context to use for encryption or decryption.
+ * \param mode The operation to perform:
+ * - #MBEDTLS_GCM_ENCRYPT to perform authenticated encryption.
+ * The ciphertext is written to \p output and the
+ * authentication tag is written to \p tag.
+ * - #MBEDTLS_GCM_DECRYPT to perform decryption.
+ * The plaintext is written to \p output and the
+ * authentication tag is written to \p tag.
+ * Note that this mode is not recommended, because it does
+ * not verify the authenticity of the data. For this reason,
+ * you should use mbedtls_gcm_auth_decrypt() instead of
+ * calling this function in decryption mode.
+ * \param length The length of the input data, which is equal to the length
+ * of the output data.
+ * \param iv The initialization vector.
+ * \param iv_len The length of the IV.
+ * \param add The buffer holding the additional data.
+ * \param add_len The length of the additional data.
+ * \param input The buffer holding the input data. Its size is \b length.
+ * \param output The buffer for holding the output data. It must have room
+ * for \b length bytes.
+ * \param tag_len The length of the tag to generate.
+ * \param tag The buffer for holding the tag.
+ *
+ * \return \c 0 if the encryption or decryption was performed
+ * successfully. Note that in #MBEDTLS_GCM_DECRYPT mode,
+ * this does not indicate that the data is authentic.
+ * \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid.
+ * \return A cipher-specific error code if the encryption or
+ * decryption failed.
*/
int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
int mode,
@@ -118,19 +140,23 @@
* If buffers overlap, the output buffer must trail at least 8 bytes
* behind the input buffer.
*
- * \param ctx GCM context
- * \param length length of the input data
- * \param iv initialization vector
- * \param iv_len length of IV
- * \param add additional data
- * \param add_len length of additional data
- * \param tag buffer holding the tag
- * \param tag_len length of the tag
- * \param input buffer holding the input data
- * \param output buffer for holding the output data
+ * \param ctx The GCM context.
+ * \param length The length of the ciphertext to decrypt, which is also
+ * the length of the decrypted plaintext.
+ * \param iv The initialization vector.
+ * \param iv_len The length of the IV.
+ * \param add The buffer holding the additional data.
+ * \param add_len The length of the additional data.
+ * \param tag The buffer holding the tag to verify.
+ * \param tag_len The length of the tag to verify.
+ * \param input The buffer holding the ciphertext. Its size is \b length.
+ * \param output The buffer for holding the decrypted plaintext. It must
+ * have room for \b length bytes.
*
- * \return 0 if successful and authenticated,
- * MBEDTLS_ERR_GCM_AUTH_FAILED if tag does not match
+ * \return \c 0 if successful and authenticated.
+ * \return #MBEDTLS_ERR_GCM_AUTH_FAILED if the tag does not match.
+ * \return #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid.
+ * \return A cipher-specific error code if the decryption failed.
*/
int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
size_t length,