noise/hkdf.go
Jonathan Rudenberg 8035b36042 Add docs
Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
2016-07-12 22:20:06 -04:00

31 lines
574 B
Go

package noise
import (
"crypto/hmac"
"hash"
)
func hkdf(h func() hash.Hash, out1, out2, chainingKey, inputKeyMaterial []byte) ([]byte, []byte) {
if len(out1) > 0 {
panic("len(out1) > 0")
}
if len(out2) > 0 {
panic("len(out2) > 0")
}
tempMAC := hmac.New(h, chainingKey)
tempMAC.Write(inputKeyMaterial)
tempKey := tempMAC.Sum(out2)
out1MAC := hmac.New(h, tempKey)
out1MAC.Write([]byte{0x01})
out1 = out1MAC.Sum(out1)
out2MAC := hmac.New(h, tempKey)
out2MAC.Write(out1)
out2MAC.Write([]byte{0x02})
out2 = out2MAC.Sum(tempKey[:0])
return out1, out2
}