Deprecate the old deterministic ECDSA function
The current interface does not allow passing an RNG, which is needed for
blinding. Using the scheme's internal HMAC-DRBG results the same
blinding values for the same key and message, diminishing the
effectiveness of the countermeasure. A new function
`mbedtls_ecdsa_det_ext` is available to address this problem.
diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index 6e4bc6c..775b58b 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -176,6 +176,12 @@
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
+#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
@@ -214,7 +220,10 @@
int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r,
mbedtls_mpi *s, const mbedtls_mpi *d,
const unsigned char *buf, size_t blen,
- mbedtls_md_type_t md_alg );
+ mbedtls_md_type_t md_alg ) MBEDTLS_DEPRECATED;
+#undef MBEDTLS_DEPRECATED
+#endif /* MBEDTLS_DEPRECATED_REMOVED */
+
/**
* \brief This function computes the ECDSA signature of a
* previously-hashed message, deterministic version.
@@ -338,7 +347,8 @@
* the signature written. Must not be \c NULL.
* \param f_rng The RNG function. This must not be \c NULL if
* #MBEDTLS_ECDSA_DETERMINISTIC is unset. Otherwise,
- * it is unused and may be set to \c NULL.
+ * it is used only for blinding and may be set to \c NULL, but
+ * doing so is DEPRECATED.
* \param p_rng The RNG context to be passed to \p f_rng. This may be
* \c NULL if \p f_rng is \c NULL or doesn't use a context.
*