vipulved / perl-crypt-rsa Goto Github PK

EMSA-PSS : https://tools.ietf.org/html/rfc8017#section-9.1
$params{Message} || $params{Plaintext} = EMSA-PSS's mHash，but not M

Hello,
I believe there may an error in the mgf1 method in Crypt::RSA::DataFormat.
According to the RSA-OAEP Encryption Scheme spec (http://www.inf.pucrs.br/~calazans/graduate/TPVLSI_I/RSA-oaep_spec.pdf) the loop in the mask generating function is "for i = 0 to ceil(l/hlen) - 1", so the loop counter ought to be increasing by 1. But in the mgf1 method, the loop counter increases by $hlen = 20.
" while ($i <= $l) {
my $C = i2osp (int($i), 4);
$T .= sha1("$seed$C");
$i += $hlen;
}"
This leads to different results because the concatenated values of $seed and i2osp(i) will differ.
If this was intended, sorry to have bothered you. I am a github newbie who just wanted to let you know in case this was indeed an error. I was working on my own RSA-OAEP implementation and noticed different results from this package.