> From: Peter Eckersley <peter.eckers...@gmail.com> > To: openssl-users@openssl.org, > Date: 01/26/2012 04:42 PM > Subject: Separating the digest and signature steps of RSA signing > > I have an offline system that needs to compute RSA signatures over > large blobs of data, given only hashes of the data as input and not > the entire blobs (something like the NONEwithRSA algorithm in Java's > RSA implementation > http://www.docjar.com/docs/api/sun/security/mscapi/RSASignature.html) > > Is there any way to do that with openssl?
Yes. - start with the hash - prepend the OID of your choice - prepend the desired padding if it's not supported, or RSA_padding_add_PKCS1_type_1(), etc. - RSA_private_encrypt(RSA_NO_PADDING)
