A CAdES Basic Electronic Signature (CAdES-BES) contains, among other
specifications, a collection of Signing Certificate reference attributes,
stored in the signedData ether as ESS signing-certificate or as
ESS signing-certificate-v2. These are described in detail in Section 5.7.2
of RFC 5126 - CMS Advanced Electronic Signatures (CAdES).
This patch adds support for adding ESS signing-certificate[-v2] attributes
to CMS signedData. Although it implements only a small part of the RFC, it
is sufficient many cases to enable the `openssl cms` app to create signatures
which comply with legal requirements of some European States (e.g Italy).
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/7893)
