mirror of
https://github.com/cwinfo/matterbridge.git
synced 2024-11-14 16:40:26 +00:00
48 lines
1.4 KiB
Go
48 lines
1.4 KiB
Go
/*
|
|
HKDF is a simple key derivation function (KDF) based on
|
|
a hash-based message authentication code (HMAC). It was initially proposed by its authors as a building block in
|
|
various protocols and applications, as well as to discourage the proliferation of multiple KDF mechanisms.
|
|
The main approach HKDF follows is the "extract-then-expand" paradigm, where the KDF logically consists of two modules:
|
|
the first stage takes the input keying material and "extracts" from it a fixed-length pseudorandom key, and then the
|
|
second stage "expands" this key into several additional pseudorandom keys (the output of the KDF).
|
|
*/
|
|
package hkdf
|
|
|
|
import (
|
|
"crypto/sha256"
|
|
"fmt"
|
|
"golang.org/x/crypto/hkdf"
|
|
"io"
|
|
)
|
|
|
|
/*
|
|
Expand expands a given key with the HKDF algorithm.
|
|
*/
|
|
func Expand(key []byte, length int, info string) ([]byte, error) {
|
|
var h io.Reader
|
|
if info == "" {
|
|
/*
|
|
Only used during initial login
|
|
Pseudorandom Key is provided by server and has not to be created
|
|
*/
|
|
h = hkdf.Expand(sha256.New, key, []byte(info))
|
|
} else {
|
|
/*
|
|
Used every other time
|
|
Pseudorandom Key is created during kdf.New
|
|
This is the normal that crypto/hkdf is used
|
|
*/
|
|
h = hkdf.New(sha256.New, key, nil, []byte(info))
|
|
}
|
|
out := make([]byte, length)
|
|
n, err := io.ReadAtLeast(h, out, length)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if n != length {
|
|
return nil, fmt.Errorf("new key to short")
|
|
}
|
|
|
|
return out, nil
|
|
}
|