Add SHA-256-only support for EVP_PKEY_RSA_PSS

While, in principle, PSS is better than PKCS#1 v1.5, and
algorithm-specific keys are better than mixing them up, RSASSA-PSS was
so badly mis-standardized in RFC 3447 and RFC 4055 that this is not
worth it. Any marginal benefits one might get from PSS is completely
overshadowed by the mountain of unforced errors those two RFCs made.
Applications are better off just using ECDSA.

Nonetheless, it is a thing we are now supporting. Add off-by-default
support for EVP_PKEY_RSA_PSS, only using the SHA-256 parameter set. In
OpenSSL's implementation, the underlying RSA object stores an
RSA_PSS_PARAMS, though the RSA-level APIs don't enforce the parameters,
only the EVP-level APIs do. For now, since the SHA-256 parameters are
the only ones we support, I have not bothered adding extra state to the
RSA object. If we need to add more parameters, we can store the
rsa_pss_params_t enum on the RSA object. (Preferably after we've split
the BCM and non-BCM halves of the RSA object.)

This support is off by default and must remain so. We have a bit of a
mess API-wise: OpenSSL made EVP_PKEY_get0_RSA work with
EVP_PKEY_RSA_PSS. This is plausible in that applications may want to
inspect RSA components and that is, for now, the API to do so. However,
existing callers generally assume a non-NULL EVP_PKEY_get0_RSA return
implies EVP_PKEY_RSA. Changing this will break those callers.

Thus the opt-in not only limits a badly-designed key type, but also
prevents existing callers from being exposed to this unexpected state.

These keys are not wired up to libssl and we have no plans to do so.

Bug: 384818542
Change-Id: I4d99be86ce1d891a2e50335ef097913707ede55a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/81656
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
11 files changed
tree: 0cc8c557521c7ee539b02704d7459aafbf689db1
  1. .bcr/
  2. .github/
  3. cmake/
  4. crypto/
  5. decrepit/
  6. docs/
  7. fuzz/
  8. gen/
  9. include/
  10. infra/
  11. pki/
  12. rust/
  13. ssl/
  14. third_party/
  15. tool/
  16. util/
  17. .bazelignore
  18. .bazelrc
  19. .bazelversion
  20. .clang-format
  21. .gitignore
  22. API-CONVENTIONS.md
  23. AUTHORS
  24. BREAKING-CHANGES.md
  25. BUILD.bazel
  26. build.json
  27. BUILDING.md
  28. CMakeLists.txt
  29. codereview.settings
  30. CONTRIBUTING.md
  31. FUZZING.md
  32. go.mod
  33. go.sum
  34. INCORPORATING.md
  35. LICENSE
  36. MODULE.bazel
  37. MODULE.bazel.lock
  38. PORTING.md
  39. PrivacyInfo.xcprivacy
  40. README.md
  41. SANDBOXING.md
  42. STYLE.md
README.md

BoringSSL

BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

Project links:

To file a security issue, use the Chromium process and mention in the report this is for BoringSSL. You can ignore the parts of the process that are specific to Chromium/Chrome.

There are other files in this directory which might be helpful: