Test, re-document, and deprecate EVP_Cipher.

It would be nice to have a single-shot EVP_CIPHER_CTX API. This function
is not it.

EVP_Cipher is absurd. It's actually just exposing the internal
EVP_CIPHER 'cipher' callback, whose calling convention is extremely
complex. We've currently documented it as a "single-shot" API, but it's
not single-shot either, as it does update cipher state. It just can't
update across block boundaries.

It is particularly bizarre for "custom ciphers", which include AEADs,
which completely changes the return value convention from
bytes_written/-1 to 1/0, but also adds a bunch of magic NULL behaviors:

- out == NULL, in != NULL: supply AAD
- out != NULL, in != NULL: bulk encrypt/decrypt
- out == NULL, in == NULL: compute/check the tag

Moreover, existing code, like OpenSSH, relies on this behavior. To
ensure we don't break it when refactoring EVP_CIPHER internals, capture
the current behavior in tests. But also, no one should be using this in
new code, so deprecate it.

Upstream hasn't quite deprecated it, they now say "Due to the
constraints of the API contract of this function it shouldn't be used in
applications, please consider using EVP_CipherUpdate() and
EVP_CipherFinal_ex() instead."

Bug: 494
Change-Id: Icfe39a8fbbc860b03c9861f4164b7ee8da340216
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/55391
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
2 files changed
tree: 72ec066be2c5219349b9f8c38d0e59606f98aa17
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. rust/
  7. ssl/
  8. third_party/
  9. tool/
  10. util/
  11. .clang-format
  12. .gitignore
  13. API-CONVENTIONS.md
  14. BREAKING-CHANGES.md
  15. BUILDING.md
  16. CMakeLists.txt
  17. codereview.settings
  18. CONTRIBUTING.md
  19. FUZZING.md
  20. go.mod
  21. go.sum
  22. INCORPORATING.md
  23. LICENSE
  24. OpenSSLConfig.cmake
  25. PORTING.md
  26. README.md
  27. SANDBOXING.md
  28. sources.cmake
  29. 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:

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