=item B<-pubin>
-the input file is a public key.
+the input file is a public key.
=item B<-certin>
-the input is a certificate containing a public key.
+the input is a certificate containing a public key.
=item B<-rev>
Use key derivation function B<algorithm>. The supported algorithms are
at present B<TLS1-PRF> and B<HKDF>.
-Note: additional paramers and the KDF output length will normally have to be
+Note: additional parameters and the KDF output length will normally have to be
set for this to work. See L<EVP_PKEY_HKDF(3)> and L<EVP_PKEY_TLS1_PRF(3)>
for the supported string parameters of each algorithm.
PKCS#1 padding, B<sslv23> for SSLv23 padding, B<none> for no padding, B<oaep>
for B<OAEP> mode, B<x931> for X9.31 mode and B<pss> for PSS.
-In PKCS#1 padding if the message digest is not set then the supplied data is
+In PKCS#1 padding if the message digest is not set then the supplied data is
signed or verified directly instead of using a B<DigestInfo> structure. If a
digest is set then the a B<DigestInfo> structure is used and its the length
must correspond to the digest type.
additional options other than B<digest>. Only the SHA1 digest can be used and
this digest is assumed by default.
+=head1 X25519 ALGORITHM
+
+The X25519 algorithm supports key derivation only. Currently there are no
+additional options.
+
=head1 EXAMPLES
Sign some data using a private key:
L<dgst(1)>, L<rsa(1)>, L<genrsa(1)>,
L<EVP_PKEY_HKDF(3)>, L<EVP_PKEY_TLS1_PRF(3)>
-=cut
-
=head1 COPYRIGHT
Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.