165 lines
3.6 KiB
Go
165 lines
3.6 KiB
Go
package encryption
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/ecdsa"
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"crypto/rand"
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"encoding/binary"
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"errors"
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"io"
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"time"
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"github.com/status-im/status-go/eth-node/crypto"
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"github.com/status-im/status-go/eth-node/crypto/ecies"
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)
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const keyBumpValue = uint64(10)
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// GetCurrentTime64 returns the current unix time in milliseconds
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func GetCurrentTime() uint64 {
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return (uint64)(time.Now().UnixMilli())
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}
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// bumpKeyID takes a timestampID and returns its value incremented by the keyBumpValue
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func bumpKeyID(timestampID uint64) uint64 {
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return timestampID + keyBumpValue
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}
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func generateHashRatchetKeyID(groupID []byte, timestamp uint64, keyBytes []byte) []byte {
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var keyMaterial []byte
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keyMaterial = append(keyMaterial, groupID...)
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timestampBytes := make([]byte, 8) // 8 bytes for a uint64
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binary.LittleEndian.PutUint64(timestampBytes, timestamp)
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keyMaterial = append(keyMaterial, timestampBytes...)
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keyMaterial = append(keyMaterial, keyBytes...)
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return crypto.Keccak256(keyMaterial)
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}
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func publicKeyMostRelevantBytes(key *ecdsa.PublicKey) uint32 {
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keyBytes := crypto.FromECDSAPub(key)
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return binary.LittleEndian.Uint32(keyBytes[1:5])
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}
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func encrypt(plaintext []byte, key []byte, reader io.Reader) ([]byte, error) {
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c, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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gcm, err := cipher.NewGCM(c)
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, gcm.NonceSize())
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if _, err = io.ReadFull(reader, nonce); err != nil {
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return nil, err
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}
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return gcm.Seal(nonce, nonce, plaintext, nil), nil
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}
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func generateSharedKey(privateKey *ecdsa.PrivateKey, publicKey *ecdsa.PublicKey) ([]byte, error) {
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const encryptedPayloadKeyLength = 16
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return ecies.ImportECDSA(privateKey).GenerateShared(
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ecies.ImportECDSAPublic(publicKey),
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encryptedPayloadKeyLength,
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encryptedPayloadKeyLength,
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)
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}
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func buildGroupRekeyMessage(privateKey *ecdsa.PrivateKey, groupID []byte, timestamp uint64, keyMaterial []byte, keys []*ecdsa.PublicKey) (*RekeyGroup, error) {
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message := &RekeyGroup{
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Timestamp: timestamp,
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}
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message.Keys = make(map[uint32][]byte)
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for _, k := range keys {
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sharedKey, err := generateSharedKey(privateKey, k)
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if err != nil {
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return nil, err
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}
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encryptedKey, err := encrypt(keyMaterial, sharedKey, rand.Reader)
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if err != nil {
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return nil, err
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}
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kBytes := publicKeyMostRelevantBytes(k)
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if message.Keys[kBytes] == nil {
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message.Keys[kBytes] = encryptedKey
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} else {
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message.Keys[kBytes] = append(message.Keys[kBytes], encryptedKey...)
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}
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}
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return message, nil
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}
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const nonceLength = 12
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func decrypt(cyphertext []byte, key []byte) ([]byte, error) {
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if len(cyphertext) < nonceLength {
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return nil, errors.New("invalid cyphertext length")
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}
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c, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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gcm, err := cipher.NewGCM(c)
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if err != nil {
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return nil, err
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}
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nonce := cyphertext[:nonceLength]
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return gcm.Open(nil, nonce, cyphertext[nonceLength:], nil)
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}
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const keySize = 60
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func decryptGroupRekeyMessage(privateKey *ecdsa.PrivateKey, publicKey *ecdsa.PublicKey, message *RekeyGroup) ([]byte, error) {
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kBytes := publicKeyMostRelevantBytes(&privateKey.PublicKey)
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if message.Keys == nil || message.Keys[kBytes] == nil {
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return nil, nil
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}
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sharedKey, err := generateSharedKey(privateKey, publicKey)
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if err != nil {
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return nil, err
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}
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keys := message.Keys[kBytes]
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nKeys := len(keys) / keySize
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var decryptedKey []byte
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for i := 0; i < nKeys; i++ {
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encryptedKey := keys[i*keySize : i*keySize+keySize]
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decryptedKey, err = decrypt(encryptedKey, sharedKey)
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if err != nil {
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continue
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} else {
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break
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}
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}
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return decryptedKey, nil
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}
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