99 lines
2.3 KiB
Go
99 lines
2.3 KiB
Go
package common
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"encoding/base64"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
|
|
"golang.org/x/crypto/chacha20poly1305"
|
|
)
|
|
|
|
// GenerateKey returns a base64-encoded 32-byte random key suitable to use as the
|
|
// symmetric passphrase for age scrypt mode. Store this securely (never in Git).
|
|
func GenerateKey() (string, error) {
|
|
k := make([]byte, 32)
|
|
if _, err := rand.Read(k); err != nil {
|
|
return "", err
|
|
}
|
|
out := make([]byte, base64.StdEncoding.EncodedLen(len(k)))
|
|
base64.StdEncoding.Encode(out, k)
|
|
return string(out), nil
|
|
}
|
|
|
|
func decodeKey(b64 string) ([]byte, error) {
|
|
key, err := base64.StdEncoding.DecodeString(b64) // standard padded
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if len(key) != chacha20poly1305.KeySize {
|
|
return nil, fmt.Errorf("bad key length: got %d, want %d", len(key), chacha20poly1305.KeySize)
|
|
}
|
|
return key, nil
|
|
}
|
|
|
|
func EncryptFileXChaCha(keyB64, inPath, outPath string, aad []byte) error {
|
|
key, err := decodeKey(keyB64)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
aead, err := chacha20poly1305.NewX(key)
|
|
if err != nil {
|
|
return fmt.Errorf("new aead: %w", err)
|
|
}
|
|
|
|
plaintext, err := os.ReadFile(inPath)
|
|
if err != nil {
|
|
return fmt.Errorf("read input: %w", err)
|
|
}
|
|
|
|
nonce := make([]byte, chacha20poly1305.NonceSizeX) // 24 bytes
|
|
if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
|
|
return fmt.Errorf("nonce: %w", err)
|
|
}
|
|
|
|
ciphertext := aead.Seal(nil, nonce, plaintext, aad)
|
|
|
|
// Write: nonce || ciphertext
|
|
out := make([]byte, 0, len(nonce)+len(ciphertext))
|
|
out = append(out, nonce...)
|
|
out = append(out, ciphertext...)
|
|
|
|
if err := os.WriteFile(outPath, out, 0600); err != nil {
|
|
return fmt.Errorf("write output: %w", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func DecryptFileFromBytes(keyB64 string, inBytes []byte, outPath string, aad []byte) error {
|
|
key, err := decodeKey(keyB64)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
aead, err := chacha20poly1305.NewX(key)
|
|
if err != nil {
|
|
return fmt.Errorf("new aead: %w", err)
|
|
}
|
|
|
|
if len(inBytes) < chacha20poly1305.NonceSizeX {
|
|
return errors.New("ciphertext too short")
|
|
}
|
|
|
|
nonce := inBytes[:chacha20poly1305.NonceSizeX]
|
|
ciphertext := inBytes[chacha20poly1305.NonceSizeX:]
|
|
|
|
plaintext, err := aead.Open(nil, nonce, ciphertext, aad)
|
|
if err != nil {
|
|
return fmt.Errorf("decrypt/auth failed: %w", err)
|
|
}
|
|
|
|
if err := os.WriteFile(outPath, plaintext, 0640); err != nil {
|
|
return fmt.Errorf("write output: %w", err)
|
|
}
|
|
return nil
|
|
}
|