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package main
import (
"bufio"
"bytes"
"crypto/sha256"
"encoding/hex"
"fmt"
"golang.org/x/crypto/hkdf"
"io"
"os"
"strconv"
"strings"
)
func unhexlify(s string) []byte {
bytes, err := hex.DecodeString(s)
if err != nil {
panic(err)
}
return bytes
}
func verifier(l uint64, ikm, okm []byte) bool {
hash := sha256.New
hkdf := hkdf.New(hash, ikm, nil, nil)
okmComputed := make([]byte, l)
io.ReadFull(hkdf, okmComputed)
return bytes.Equal(okmComputed, okm)
}
func validateVectors(filename string) bool {
vectors, err := os.Open(filename)
if err != nil {
panic(err)
}
defer vectors.Close()
var segments []string
var l uint64
var ikm, okm string
scanner := bufio.NewScanner(vectors)
for scanner.Scan() {
segments = strings.Split(scanner.Text(), " = ")
switch {
case strings.ToUpper(segments[0]) == "L":
l, err = strconv.ParseUint(segments[1], 10, 64)
if err != nil {
panic(err)
}
case strings.ToUpper(segments[0]) == "IKM":
ikm = segments[1]
case strings.ToUpper(segments[0]) == "OKM":
okm = segments[1]
}
}
return verifier(l, unhexlify(ikm), unhexlify(okm))
}
func main() {
if validateVectors("vectors/cryptography_vectors/KDF/hkdf-generated.txt") {
fmt.Println("HKDF OK.")
} else {
fmt.Println("HKDF failed.")
os.Exit(1)
}
}
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