libgocryptfs/internal/cryptocore/hkdf.go
Jakob Unterwurzacher d0bc7970f7 full stack: implement HKDF support
...but keep it disabled by default for new filesystems.

We are still missing an example filesystem and CLI arguments
to explicitely enable and disable it.
2017-03-05 21:59:55 +01:00

22 lines
524 B
Go

package cryptocore
import (
"crypto/sha256"
"log"
"golang.org/x/crypto/hkdf"
)
// hkdfDerive derives "outLen" bytes from "masterkey" and "info" using
// HKDF-SHA256.
// It returns the derived bytes or panics.
func hkdfDerive(masterkey []byte, info string, outLen int) (out []byte) {
h := hkdf.New(sha256.New, masterkey, nil, []byte(info))
out = make([]byte, outLen)
n, err := h.Read(out)
if n != outLen || err != nil {
log.Panicf("hkdfDerive: hkdf read failed, got %d bytes, error: %v", n, err)
}
return out
}