1=pod 2 3=head1 NAME 4 5RSA-PSS - EVP_PKEY RSA-PSS algorithm support 6 7=head1 DESCRIPTION 8 9The B<RSA-PSS> EVP_PKEY implementation is a restricted version of the RSA 10algorithm which only supports signing, verification and key generation 11using PSS padding modes with optional parameter restrictions. 12 13It has associated private key and public key formats. 14 15This algorithm shares several control operations with the B<RSA> algorithm 16but with some restrictions described below. 17 18=head2 Signing and Verification 19 20Signing and verification is similar to the B<RSA> algorithm except the 21padding mode is always PSS. If the key in use has parameter restrictions then 22the corresponding signature parameters are set to the restrictions: 23for example, if the key can only be used with digest SHA256, MGF1 SHA256 24and minimum salt length 32 then the digest, MGF1 digest and salt length 25will be set to SHA256, SHA256 and 32 respectively. 26 27=head2 Key Generation 28 29By default no parameter restrictions are placed on the generated key. 30 31=head1 NOTES 32 33The public key format is documented in RFC4055. 34 35The PKCS#8 private key format used for RSA-PSS keys is similar to the RSA 36format except it uses the B<id-RSASSA-PSS> OID and the parameters field, if 37present, restricts the key parameters in the same way as the public key. 38 39=head1 CONFORMING TO 40 41RFC 4055 42 43=head1 SEE ALSO 44 45L<EVP_PKEY_CTX_set_rsa_pss_keygen_md(3)>, 46L<EVP_PKEY_CTX_set_rsa_pss_keygen_mgf1_md(3)>, 47L<EVP_PKEY_CTX_set_rsa_pss_keygen_saltlen(3)>, 48L<EVP_PKEY_CTX_new(3)>, 49L<EVP_PKEY_CTX_ctrl_str(3)>, 50L<EVP_PKEY_derive(3)> 51 52=head1 COPYRIGHT 53 54Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved. 55 56Licensed under the Apache License 2.0 (the "License"). You may not use 57this file except in compliance with the License. You can obtain a copy 58in the file LICENSE in the source distribution or at 59L<https://www.openssl.org/source/license.html>. 60 61=cut 62