diff --git a/library/bignum_core.h b/library/bignum_core.h
index 120fa18..eeca41e 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -512,6 +512,43 @@
                                   int (*f_rng)(void *, unsigned char *, size_t),
                                   void *p_rng );
 
+/** Generate a random number uniformly in a range.
+ *
+ * This function generates a random number between \p min inclusive and
+ * \p N exclusive.
+ *
+ * The procedure complies with RFC 6979 §3.3 (deterministic ECDSA)
+ * when the RNG is a suitably parametrized instance of HMAC_DRBG
+ * and \p min is \c 1.
+ *
+ * \note           There are `N - min` possible outputs. The lower bound
+ *                 \p min can be reached, but the upper bound \p N cannot.
+ *
+ * \param X        The destination MPI, with \p limbs limbs.
+ *                 It must not be aliased with \p N or otherwise overlap it.
+ * \param min      The minimum value to return.
+ * \param N        The upper bound of the range, exclusive, with \p limbs limbs.
+ *                 In other words, this is one plus the maximum value to return.
+ *                 \p N must be strictly larger than \p min.
+ * \param limbs    The number of limbs of \p N and \p X.
+ *                 This must not be 0.
+ * \param f_rng    The RNG function to use. This must not be \c NULL.
+ * \param p_rng    The RNG parameter to be passed to \p f_rng.
+ *
+ * \return         \c 0 if successful.
+ * \return         #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if the implementation was
+ *                 unable to find a suitable value within a limited number
+ *                 of attempts. This has a negligible probability if \p N
+ *                 is significantly larger than \p min, which is the case
+ *                 for all usual cryptographic applications.
+ */
+int mbedtls_mpi_core_random( mbedtls_mpi_uint *X,
+                             mbedtls_mpi_uint min,
+                             const mbedtls_mpi_uint *N,
+                             size_t limbs,
+                             int (*f_rng)(void *, unsigned char *, size_t),
+                             void *p_rng );
+
 /* BEGIN MERGE SLOT 1 */
 
 /**