I’m trying to verify an S/MIME signed email with openssl (term tooling) but I’m having a problem. I have the mail and I can extract the chain of certificates but I’m failing at locating the actual signature of the email. I have the public key of the signer (the last certificate) and I have the plaintext, which I got with
openssl smime -verify -in <mail> -noverify -out mail_body.txt
If I understand correctly now I need the signature, decrypt it with the last certifier public key and check that with the hash of mail_body.txt but I can’t find the signature.