tree d8eff2c86b444163ec42b38bb0c5cc1e293e1fa8
parent f18638cca14d0b02617785e848a5afaa2715f71a
author David Benjamin <davidben@google.com> 1604358974 -0500
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1604447039 +0000

Add functions for manipulating X.509 TBS structures.

When generating a signature with some external signing process, the
caller needs to fill in the TBSCertificate (including the signature
algorithms), serialize the TBSCertificate, and then fill in the
signature.

We have i2d_re_X509_tbs (originally from CT I believe), but there are no
setters for the signature algorithms or the signature. Add
X509_set1_signature_algo, which mirrors upstream's
X509_REQ_set1_signature_algo, and X509_set1_signature_value, which is
new. Upstream has X509_REQ_set0_signature, but that requires the caller
manually assemble an ASN1_BIT_STRING. Taking the byte string seems less
error-prone.

Additionally, add i2d_X509_tbs and i2d_X509_CRL_tbs, for the non-"re"
variants of those APIs. Conscrypt needs to extract the TBS portion of a
certificate and a CRL, to implement X509Certificate.getTBSCertificate()
and X509CRL.getTBSCertList(). There, the aim is to get the data to
verify on an existing immutable certificate. OpenSSL has avoided
exporting the X509_CINF type, which I think is correct, so instead this
mirrors i2d_re_X509_tbs. (This does mean mirroring the confusing i2d
calling convention though.)

These new functions should unblock getting rid of a bunch of direct
struct accesses.

Later on, we should reorganize this header into immutable APIs for
verification and mutable APIs for generation. Even though we're stuck
the mistake of a common type for both use cases, I think splitting up
them up will let us rationalize the caches in the X509 objects a bit.

Change-Id: I96e6ab5cee3608e07b2ed7465c449a72ca10a393
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/43784
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>