psa_util: improve convert_raw_to_der_single_int()
Allow the function to support DER buffers than what it is nominally
required by the provided coordinates. In other words let's ignore
padding zeros in the raw number.
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index 06732d8..132c73f 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -191,7 +191,12 @@
* \param raw_len Length of \p raw in bytes.
* \param[out] der Buffer that will be filled with the converted DER
* output. It can overlap with raw buffer.
- * \param der_size Size of \p der in bytes.
+ * \param der_size Size of \p der in bytes. Given \p bits parameter:
+ * * #MBEDTLS_ECDSA_MAX_SIG_LEN(\p bits) can be used
+ * to determine a large enough buffer for any
+ * \p raw input vector.
+ * * The minimum size might be smaller in case
+ * \p raw input vector contains padding zeros.
* \param[out] der_len On success it contains the amount of valid data
* (in bytes) written to \p der. It's undefined
* in case of failure.