A minimal set of simple, safe functions for Montgomery arithmetic,
designed for cryptographic primitives.
Also update the current RSA cert validation to use it, getting rid
of the FixedBuffer hack and the previous limitations.
Make the check of the RSA public key a little bit more strict by
the way.
The majority of these are in comments, some in doc comments which might
affect the generated documentation, and a few in parameter names -
nothing that should be breaking, however.
Previously, the code only checked Common Name, leading to unable to
validate valid certificates which relied on the subject_alt_name
extension for host name verification.
This commit also adds rsa_pss_rsae_* back to the signature algorithms
list in the ClientHello.
The code we are borrowing from https://github.com/shiguredo/tls13-zig
requires an Allocator for doing RSA certificate verification. As a
stopgap measure, this commit uses a FixedBufferAllocator to avoid heap
allocation for these functions.
Thank you to @naoki9911 for providing this great resource which has been
extremely helpful for me when working on this standard library TLS
implementation. Until Zig has std.crypto.rsa officially, we will borrow
this implementation of RSA. 🙏
Only a little bit of generalized logic for DER encoding is needed and so
it can live inside the Certificate namespace.
This commit removes the generic "parse object id" function which is no
longer used in favor of more specific, smaller sets of object ids used
with ComptimeStringMap.
When scanning the file system for root certificates, expired
certificates are skipped and therefore not used for verification in TLS
sessions. There is only this one check, however, so a long-running
server will need to periodically rescan for a new Certificate.Bundle
and strategically start using it for new sessions. In this commit I made
the judgement call that applications would like to opt-in to root
certificate rescanning at a point in time that makes sense for that
application, as opposed to having the system clock potentially start
causing connections to fail.
Certificate verification checks the subject only, as opposed to both the
subject and the issuer. The idea is that the trust chain analysis will
always check the subject, leading to every certificate in the chain's
validity being checked exactly once, with the root certificate's
validity checked upon scanning.
Furthermore, this commit adjusts the scanning logic to fully parse
certificates, even though only the subject is technically needed. This
allows relying on parsing to succeed later on.
