Add ECDSA sign primitive
diff --git a/include/polarssl/ecdsa.h b/include/polarssl/ecdsa.h
index cf7a788..39a0626 100644
--- a/include/polarssl/ecdsa.h
+++ b/include/polarssl/ecdsa.h
@@ -34,6 +34,25 @@
#endif
/**
+ * \brief Compute ECDSA signature of a previously hashed message
+ *
+ * \param grp ECP group
+ * \param r First output integer
+ * \param s Second output integer
+ * \param d Private signing key
+ * \param buf Message hash
+ * \param blen Length of buf
+ * \param f_rng RNG function
+ * \param p_rng RNG parameter
+ *
+ * \return 0 if successful,
+ * or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
+ */
+int ecdsa_sign( const ecp_group *grp, mpi *r, mpi *s,
+ const mpi *d, const unsigned char *buf, size_t blen,
+ int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
+
+/**
* \brief Checkup routine
*
* \return 0 if successful, or 1 if the test failed