On Mon, 14 Mar 2022 at 11:03, Tomas Mraz <to...@openssl.org> wrote: > On Mon, 2022-03-14 at 08:58 -0300, Richard Dymond wrote: > > By the way, the reason I need to get the 'r' and 's' values from the > > DSA signature is that I am encoding them one after the other as 160- > > bit unsigned integers, in network byte order, as required by SSH and > > described in section 6.6 of RFC 4253 (dss_signature_blob)[1]. To do > > this encoding I am calling BN_bn2bin() twice to write 'r' followed by > > 's' at the appropriate locations in a 40-byte buffer. By any chance, > > does OpenSSL 3.0 provide any support for encoding a DSA signature > > like this from a DSA_SIG (i.e. without having to extract 'r' and 's' > > first and then use BN_bn2bin())? > > No, there is no such function. However there is not much overhead in > doing the two BN_bn2bin calls (should those be BN_bn2binpad actually?) > once you already have a DSA_SIG object. >
OK, I suppose that was hoping for too much. But thanks for the tip regarding BN_bn2binpad v. BN_bn2bin - that does simplify the code a little more. Richard