Node / rns-mirrors / Reticulum-Go.git / files / pkg / cryptography / group_key.go

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// SPDX-License-Identifier: Apache-2.0

// Copyright (c) 2024-2026 Quad4.io

package cryptography

import (

"crypto/sha256"

"io"

"golang.org/x/crypto/hkdf"

)

var encryptWithHMACInfo = []byte("identity.EncryptWithHMAC.v1")

func implExpandEncryptWithHMACKeyMaterial(key32 []byte) (hmacKey, aesKey []byte, err error) {

salt := make([]byte, SHA256Size)

r := hkdf.New(sha256.New, key32, salt, encryptWithHMACInfo)

out := make([]byte, IdentityKeyMaterialSize)

if _, err := io.ReadFull(r, out); err != nil {

return nil, nil, err

}

return out[:32], out[32:], nil

}

// ExpandEncryptWithHMACKeyMaterial derives 32-byte HMAC and 32-byte AES keys from a

// 32-byte input using HKDF-SHA256 (RFC 5869).

func ExpandEncryptWithHMACKeyMaterial(key32 []byte) (hmacKey, aesKey []byte, err error) {

return ActiveProvider().ExpandEncryptWithHMACKeyMaterial(key32)

}