New function mbedtls_ecp_keypair_calc_public
For when you calculate or import a private key, and then need to calculate
the public key.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 96f030d..1847f2c 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -1365,6 +1365,23 @@
const mbedtls_ecp_keypair *pub, const mbedtls_ecp_keypair *prv,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng);
+/** \brief Calculate the public key from a private key in a key pair.
+ *
+ * \param key A keypair structure. It must have a private key set.
+ * If the public key is set, it will be overwritten.
+ * \param f_rng The RNG function. This must not be \c NULL.
+ * \param p_rng The RNG context to be passed to \p f_rng. This may be \c
+ * NULL if \p f_rng doesn't need a context.
+ *
+ * \return \c 0 on success. The key pair object can be used for
+ * operations that require the public key.
+ * \return An \c MBEDTLS_ERR_ECP_XXX or an \c MBEDTLS_ERR_MPI_XXX
+ * error code on calculation failure.
+ */
+int mbedtls_ecp_keypair_calc_public(
+ mbedtls_ecp_keypair *key,
+ int (*f_rng)(void *, unsigned char *, size_t), void *p_rng);
+
/** \brief Query the group that a key pair belongs to.
*
* \param key The key pair to query.