Switch to go1.26 crypto/hpke

[rthellend]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @rthellend, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly refactors the project's cryptographic operations by transitioning from a custom HPKE implementation to the official crypto/hpke package introduced in Go 1.26. This change enhances maintainability, security, and leverages the Go standard library's robust and well-tested cryptographic primitives. The update also involves bumping the required Go version and cleaning up obsolete internal HPKE-related files.

Highlights

• HPKE Implementation Migration: The project has migrated its HPKE (Hybrid Public Key Encryption) implementation from a custom internal package to the standard crypto/hpke package available in Go 1.26.
• Go Version Update: The Go module has been updated to require Go 1.26.0, aligning with the availability of the new crypto/hpke package.
• Dependency Updates and Cleanup: The golang.org/x/crypto dependency has been updated to a newer version, and the previously used internal HPKE package and its related files have been removed.
• API Adaptation: Code interacting with HPKE, including setup for both sender and recipient, has been refactored to use the new standard library API, including hpke.NewRecipient, hpke.NewSender, and specific KEM/AEAD identifiers.

Changelog

• ech.go
  • Added crypto/ecdh and crypto/hpke imports for standard library cryptography.
  • Removed the import for the internal HPKE package.
  • Corrected a typo in the hpkeCtx field type from hpke.Receipient to hpke.Recipient.
  • Updated HPKE recipient setup logic to use ecdh.X25519().NewPrivateKey, hpke.NewDHKEMPrivateKey, hpke.NewKDF, hpke.NewAEAD, and hpke.NewRecipient from the standard library.
• ech_test.go
  • Added crypto/hpke import for standard library HPKE functions.
  • Removed the import for the internal HPKE package.
  • Updated HPKE sender setup in tests to use hpke.NewDHKEMPublicKey, hpke.NewSender, hpke.HKDFSHA256(), and hpke.ChaCha20Poly1305() from the standard library.
• go.mod
  • Updated the required Go version from 1.24 to 1.26.0.
  • Updated the golang.org/x/crypto dependency from v0.40.0 to v0.48.0.
  • Cleaned up indirect dependencies.
• go.sum
  • Updated checksums for golang.org/x/crypto and golang.org/x/sys to reflect the new versions.
• helpers_test.go
  • Added crypto/hpke import for standard library HPKE functions.
  • Removed the import for the internal HPKE package.
  • Updated AEAD constants to use hpke.ChaCha20Poly1305(), hpke.AES128GCM(), and hpke.AES256GCM() from the standard library.
  • Refactored HPKE sender setup to use hpke.NewDHKEMPublicKey, hpke.NewSender, hpke.HKDFSHA256(), and aead.ID().
• internal/hpke/LICENSE
  • Removed the license file for the internal HPKE package.
• internal/hpke/README.txt
  • Removed the README file for the internal HPKE package.
• internal/hpke/hpke.go
  • Removed the custom HPKE implementation file.
• internal/hpke/hpke_test.go
  • Removed the test file for the custom HPKE implementation.
• internal/hpke/internal/byteorder/byteorder.go
  • Removed the internal byte order utility file.
• internal/hpke/internal/fips140/hkdf/hkdf.go
  • Removed the internal HKDF implementation file.
• internal/hpke/testdata/rfc9180-vectors.json
  • Removed the test vectors for the custom HPKE implementation.

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[gemini-code-assist]

Code Review

This pull request is a great improvement, migrating from an internal/vendored HPKE implementation to the one provided in Go 1.26. The changes simplify the codebase and leverage the standard library. The API migrations and dependency updates seem correct. I've identified one bug related to handling multiple ECH keys that could lead to decryption failures, and another opportunity to improve the logic by exiting a loop early after a successful operation. Please see my detailed comments.