Please look at demos/signature/rsa_pss_direct.c If you want to use the old PKCS1 v1.5 padding then just replace RSA_PKCS1_PSS_PADDING with RSA_PKCS1_PADDING. Tomas On Thu, 2022-05-05 at 10:35 -0600, Philip Prindeville wrote: > Bonjour. Et milles mercis. > > That was helpful. > > One more question: if I want to reproduce RSA_sign() (and > RSA_verify()) using evp_key_sign() and evp_key_verify() then I'll > need add code to do the ASN.1 marshaling, right? There's no > convenience function to do that (seems like an oversight if that's > the case)? > > -Philip > > > > On May 4, 2022, at 3:45 AM, Erwann Abalea > > <Erwann.Abalea@xxxxxxxxxxxx> wrote: > > > > Bonjour, > > > > The ASN.1 structure (it's a DigestInfo) is part of the PKCS#1 v1.5 > > padding for signature operations. > > PKCS#1v1.5 is rewritten in RFC2313. > > > > Using the command line tool, you can reproduce this: > > > > echo -n "Mary had a little lamb." > datatosign > > > > either one of the following can be used to sign data: > > openssl dgst -sha1 -sign tests/keys/rsa_key1.key datatosign > > > signing > > openssl pkeyutl -inkey tests/keys/rsa_key1.key -in <(openssl dgst > > -sha1 -binary datatosign) -sign -pkeyopt digest:sha1 > signing > > > > and you can display the signature either way (this will not > > "verify", it will only perform the RSA verify operation with > > PKCS#1v1.5 padding, without checking the validity or even if what > > has been signed is a DigestInfo structure, and output the result of > > the RSA operation): > > openssl rsautl -verify -inkey tests/keys/rsa_key1.pub -pubin -in > > signing -asn1parse > > openssl pkeyutl -verifyrecover -inkey tests/keys/rsa_key1.pub - > > pubin -in signing -asn1parse > > > > or you can actually verify the thing without displaying the result > > of the RSA verify crypto operation: > > openssl pkeyutl -verify -inkey tests/keys/rsa_key1.pub -pubin -in > > <(openssl dgst -sha1 -binary datatosign) -sigfile signing -pkeyopt > > digest:sha1 > > openssl dgst -verify tests/keys/rsa_key1.pub -signature signing - > > sha1 datatosign > > > -- Tomáš Mráz, OpenSSL
