PKCS7_NOOLDMIMETYPE to use Content-Type application/pkcs7-mime
OPENSSL_CMS_OLDMIMETYPE to use Content-Type application/x-pkcs7-mime
SMIME_write_PKCS7 and SMIME_write_CMS are using SMIME_write_ASN1_ex.
The Content-Type application/x-pkcs7-mime is generated with the flag SMIME_OLDMIME (0x400).[^1]
SMIME_write_PKCS7 set SMIME_OLDMIME by default.[^2]
SMIME_write_CMS does not.[^3]
I picked OPENSSL_CMS_OLDMIMETYPE over OPENSSL_CMS_NOOLDMIMETYPE because that's what the flag actually does.
[^1]: 9a2f78e14a/crypto/asn1/asn_mime.c (L248-L251)
[^2]: 9a2f78e14a/crypto/pkcs7/pk7_mime.c (L41-L43)
[^3]: 9a2f78e14a/crypto/cms/cms_io.c (L93)
Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>
It add CMS (RFC 5652) support, which is an update to PKCS7. The functions
are analogous BUT NOT IDENTICAL to openssl_pkcs7*. In particular, support for
different encodings (PEM, DER, SMIME) is now available.
