EVP_BytesToKey() derives a key and IV from various parameters. B<type> is
the cipher to derive the key and IV for. B<md> is the message digest to use.
-The B<salt> paramter is used as a salt in the derivation: it should point to
+The B<salt> parameter is used as a salt in the derivation: it should point to
an 8 byte buffer or NULL if no salt is used. B<data> is a buffer containing
B<datal> bytes which is used to derive the keying data. B<count> is the
iteration count to use. The derived key and IV will be written to B<key>
=head1 RETURN VALUES
-EVP_BytesToKey() returns the size of the derived key in bytes, or 0 on error.
+If B<data> is NULL, then EVP_BytesToKey() returns the number of bytes
+needed to store the derived key.
+Otherwise, EVP_BytesToKey() returns the size of the derived key in bytes,
+or 0 on error.
=head1 SEE ALSO
L<evp(3)|evp(3)>, L<rand(3)|rand(3)>,
+L<PKCS5_PBKDF2_HMAC(3)|PKCS5_PBKDF2_HMAC(3)>,
L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>
=head1 HISTORY