acme/autocert: support both RSA and ECDSA clients on the fly

GetCertificate has all the information it needs to know if a client
supports ECDSA in ClientHelloInfo. Deprecate and ignore ForceRSA, and
just obtain a RSA certificate on the fly when a client that doesn't
support ECDSA connects.

This changes the cache key format to have a "+rsa" suffix for RSA
certificates. The default (ForceRSA = false) cache key is unchanged,
so most DirCache instances will still be valid. Caches created with
ForceRSA set will be silently ignored and certificates reissued.

The cache keys for HTTP tokens and the account key are changed to be
guaranteed not to overlap with valid domain names as well.

Note that ECDSA support detection is more strict in following RFC 5246
than crypto/tls, which ignores signature_algorithms.

Fixes golang/go#22066

Change-Id: I70227747b563d6849cb693f83a950d57040b3f39
Reviewed-on: https://go-review.googlesource.com/114501
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
5 files changed
tree: 15d6fd5b79602f33dc6ba0cb1e82f3177b4d0c47
  1. acme/
  2. argon2/
  3. bcrypt/
  4. blake2b/
  5. blake2s/
  6. blowfish/
  7. bn256/
  8. cast5/
  9. chacha20poly1305/
  10. cryptobyte/
  11. curve25519/
  12. ed25519/
  13. hkdf/
  14. internal/
  15. md4/
  16. nacl/
  17. ocsp/
  18. openpgp/
  19. otr/
  20. pbkdf2/
  21. pkcs12/
  22. poly1305/
  23. ripemd160/
  24. salsa20/
  25. scrypt/
  26. sha3/
  27. ssh/
  28. tea/
  29. twofish/
  30. xtea/
  31. xts/
  32. .gitattributes
  33. .gitignore
  34. AUTHORS
  35. codereview.cfg
  36. CONTRIBUTING.md
  37. CONTRIBUTORS
  38. LICENSE
  39. PATENTS
  40. README.md
README.md

Go Cryptography

This repository holds supplementary Go cryptography libraries.

Download/Install

The easiest way to install is to run go get -u golang.org/x/crypto/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/crypto.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the crypto repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/crypto:” in the subject line, so it is easy to find.

Note that contributions to the cryptography package receive additional scrutiny due to their sensitive nature. Patches may take longer than normal to receive feedback.