mirror of
https://github.com/42wim/matterbridge
synced 2024-11-19 03:25:33 +00:00
48 lines
1.3 KiB
Go
48 lines
1.3 KiB
Go
// Package kdf provides a key derivation function to calculate key output
|
|
// and negotiate shared secrets for curve X25519 keys.
|
|
package kdf
|
|
|
|
import (
|
|
"crypto/sha256"
|
|
"io"
|
|
|
|
"golang.org/x/crypto/curve25519"
|
|
"golang.org/x/crypto/hkdf"
|
|
)
|
|
|
|
// HKDF is a hashed key derivation function type that can be used to derive keys.
|
|
type HKDF func(inputKeyMaterial, salt, info []byte, outputLength int) ([]byte, error)
|
|
|
|
// DeriveSecrets derives the requested number of bytes using HKDF with the given
|
|
// input, salt, and info.
|
|
func DeriveSecrets(inputKeyMaterial, salt, info []byte, outputLength int) ([]byte, error) {
|
|
kdf := hkdf.New(sha256.New, inputKeyMaterial, salt, info)
|
|
|
|
secrets := make([]byte, outputLength)
|
|
length, err := io.ReadFull(kdf, secrets)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if length != outputLength {
|
|
return nil, err
|
|
}
|
|
|
|
return secrets, nil
|
|
}
|
|
|
|
// CalculateSharedSecret uses DH Curve25519 to find a shared secret. The result of this function
|
|
// should be used in `DeriveSecrets` to output the Root and Chain keys.
|
|
func CalculateSharedSecret(theirKey, ourKey [32]byte) [32]byte {
|
|
var sharedSecret [32]byte
|
|
curve25519.ScalarMult(&sharedSecret, &ourKey, &theirKey)
|
|
|
|
return sharedSecret
|
|
}
|
|
|
|
// KeyMaterial is a structure for representing a cipherkey, mac, and iv
|
|
type KeyMaterial struct {
|
|
CipherKey []byte
|
|
MacKey []byte
|
|
IV []byte
|
|
}
|