forked from TrueCloudLab/restic
61 lines
1.5 KiB
Go
61 lines
1.5 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package hkdf_test
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto/rand"
|
|
"crypto/sha256"
|
|
"fmt"
|
|
"golang.org/x/crypto/hkdf"
|
|
"io"
|
|
)
|
|
|
|
// Usage example that expands one master key into three other cryptographically
|
|
// secure keys.
|
|
func Example_usage() {
|
|
// Underlying hash function to use
|
|
hash := sha256.New
|
|
|
|
// Cryptographically secure master key.
|
|
master := []byte{0x00, 0x01, 0x02, 0x03} // i.e. NOT this.
|
|
|
|
// Non secret salt, optional (can be nil)
|
|
// Recommended: hash-length sized random
|
|
salt := make([]byte, hash().Size())
|
|
n, err := io.ReadFull(rand.Reader, salt)
|
|
if n != len(salt) || err != nil {
|
|
fmt.Println("error:", err)
|
|
return
|
|
}
|
|
|
|
// Non secret context specific info, optional (can be nil).
|
|
// Note, independent from the master key.
|
|
info := []byte{0x03, 0x14, 0x15, 0x92, 0x65}
|
|
|
|
// Create the key derivation function
|
|
hkdf := hkdf.New(hash, master, salt, info)
|
|
|
|
// Generate the required keys
|
|
keys := make([][]byte, 3)
|
|
for i := 0; i < len(keys); i++ {
|
|
keys[i] = make([]byte, 24)
|
|
n, err := io.ReadFull(hkdf, keys[i])
|
|
if n != len(keys[i]) || err != nil {
|
|
fmt.Println("error:", err)
|
|
return
|
|
}
|
|
}
|
|
|
|
// Keys should contain 192 bit random keys
|
|
for i := 1; i <= len(keys); i++ {
|
|
fmt.Printf("Key #%d: %v\n", i, !bytes.Equal(keys[i-1], make([]byte, 24)))
|
|
}
|
|
|
|
// Output:
|
|
// Key #1: true
|
|
// Key #2: true
|
|
// Key #3: true
|
|
}
|