This matches the implementation in NaCL, so a user can generate
a crypto_auth digest in another language and verify it with Go, or
vice versa.
Fixesgolang/go#20265.
Change-Id: Ice96abb9347a5318a16ced5152ebfa7d9ebdd285
Reviewed-on: https://go-review.googlesource.com/51932
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>