doc: document the sign function requirements in gnutls_privkey_import_ext

diff --git a/lib/privkey.c b/lib/privkey.c
index 3ea880e472de512ce8c1554cc0270c8b69845600..90a63047963af287401b5f4902d4cead283ebc66 100644 (file)
--- a/lib/privkey.c
+++ b/lib/privkey.c
@@ -533,6 +533,11 @@ gnutls_privkey_export_pkcs11(gnutls_privkey_t pkey,
  * #gnutls_privkey_t type. At least one of the two callbacks
  * must be non-null.
  *
+ * Note that the signing function is supposed to "raw" sign data, i.e.,
+ * without any hashing or preprocessing. In case of RSA the DigestInfo
+ * will be provided, and the signing function is expected to do the PKCS #1
+ * 1.5 padding and the exponentiation.
+ *
  * See also gnutls_privkey_import_ext3().
  *
  * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a