This section describes the changes made between S/MIME v3.2 and
S/MIME v4.0.
- Added the use of AuthEnvelopedData, including defining and
registering an smime-type value (Sections 2.4.4 and 3.4).
- Updated the content-encryption algorithms (Sections 2.7 and
2.7.1.2): added AES-256 Galois/Counter Mode (GCM), added
ChaCha20-Poly1305, removed mention of AES-192 Cipher Block
Chaining (CBC), and marked tripleDES as historic.
- Updated the set of signature algorithms (Section 2.2): added the
Edwards-curve Digital Signature Algorithm (EdDSA), added the
Elliptic Curve Digital Signature Algorithm (ECDSA), and marked DSA
as historic.
- Updated the set of digest algorithms (Section 2.1): added SHA-512,
and marked SHA-1 as historic.
- Updated the size of keys to be used for RSA encryption and RSA
signing (Section 4).
- Created Appendix B, which discusses considerations for dealing
with historic email messages.
