jacobsa / crypto Goto Github PK

Trying to cross compile for ARM, i got bitten by a missing implementation of the xorBlock function for ARM...

RFC 4493 has a program for generating test data with a reference
implementation and hard-coded data. That can be cgo-wrapped into a program
that generates random keys (with a hard-coded seed) and then prints gobs with
test cases for various programs.

• Command should be testing/gentests.
• Structs defined in testing.
• testing also exports functions that return the test data; finds the data
  using the source repo.

The xorBlock function does not have support for RISC-V and thus software depending on crypto e.g. gocryptfs does not compile on RISC-V:

Unfortunately, unaligned loads (which are used by the present xorBlock implementation) are implementation-defined behavior on RISC-V and should thus not be relied on (Section 2.6, "Load and Store Instructions" in the unprivileged ISA specification):

Loads and stores where the effective address is not naturally aligned to the referenced datatype (i.e., on a four-byte boundary for 32-bit accesses, and a two-byte boundary for 16-bit accesses) have behavior dependent on the EEI.

Maybe it makes sense to add a generic fallback implementation of the xorBlock function which does not make use of unaligned loads?

Alpine Linux downstream issue where this was originally reported: https://gitlab.alpinelinux.org/alpine/aports/-/issues/12793

Hi there, I am about to use SIV in gocryptfs, thanks for the great work!

I'll write an AEAD wrapper for that, just wanted to ask if you are interested in having the wrapper upstream in your repo, otherwise I'll keep it in gocryptfs.