Here’s something I wrote once upon a time when someone was asking about producing a PKCS#7 signature: How can I generate PKCS7 file? - #2 by voltone
Your requirement may be slightly different. The best place to start would be decoding a signature produced by OpenSSL to Erlang records using :public_key, e.g. :public_key.der_decode(:ContentInfo, File.read!("signature"))…
