Clarify documentation of ECP_RESTARTABLE
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 5d4033c..b4f5eb7 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -693,7 +693,8 @@
* This option:
* - Adds xxx_restartable() variants of existing operations in the
* following modules, with corresponding restart context types:
- * - ECP: scalar multiplication (mult), linear combination (muladd);
+ * - ECP (for Short Weierstrass curves only): scalar multiplication (mul),
+ * linear combination (muladd);
* - ECDSA: signature generation & verification;
* - PK: signature generation & verification;
* - X509: certificate chain verification.
@@ -701,12 +702,12 @@
* - Changes the behaviour of TLS 1.2 clients (not servers) when using the
* ECDHE-ECDSA key exchange (not other key exchanges) to make all ECC
* computations restartable:
- * - ECDH operations from the key exchange - unless MBEDTLS_USE_PSA_CRYPTO
- * is also enabled.
+ * - ECDH operations from the key exchange, only for Short Weierstass
+ * curves, only when MBEDTLS_USE_PSA_CRYPTO is not enabled.
* - verification of the server's key exchange signature;
* - verification of the server's certificate chain;
- * - generation of our signature if client authentication is used, with an
- * ECC key/certificate.
+ * - generation of the client's signature if client authentication is used,
+ * with an ECC key/certificate.
*
* \note In the cases above, the usual SSL/TLS functions, such as
* mbedtls_ssl_handshake(), can now return
@@ -715,14 +716,13 @@
* \note When this option and MBEDTLS_USE_PSA_CRYPTO are both enabled,
* restartable operations in PK, X.509 and TLS (see above) are not
* using PSA. On the other hand, ECDH computations in TLS are using
- * PSA, and are not restartable.
+ * PSA, and are not restartable. These are temporary limitations that
+ * should be lifted in the future.
*
* \note This option only works with the default software implementation of
* elliptic curve functionality. It is incompatible with
* MBEDTLS_ECP_ALT, MBEDTLS_ECDH_XXX_ALT, MBEDTLS_ECDSA_XXX_ALT.
*
- * \note This option only works for Short Weierstrass curves.
- *
* Requires: MBEDTLS_ECP_C
*
* Uncomment this macro to enable restartable ECC computations.