Files
certman/crypto.go
2026-02-19 22:49:13 +01:00

153 lines
3.6 KiB
Go

package main
import (
"crypto/rand"
"encoding/base64"
"errors"
"fmt"
"io"
"os"
_ "filippo.io/age"
"golang.org/x/crypto/chacha20poly1305"
)
//var cert *x509.Certificate
//var key *rsa.PrivateKey
//
//func encryptBytes(data []byte) []byte {
// if cert == nil || key == nil {
// loadCerts()
// }
//
// encrypted, err := rsa.EncryptPKCS1v15(rand.Reader, cert.PublicKey.(*rsa.PublicKey), data)
// if err != nil {
// fmt.Println("Error encrypting data,", err)
// os.Exit(1)
// }
// return encrypted
//}
//
//func decryptBytes(data []byte) []byte {
// if cert == nil || key == nil {
// loadCerts()
// }
//
// decrypted, err := rsa.DecryptPKCS1v15(rand.Reader, key, data)
// if err != nil {
// fmt.Println("Error decrypting data,", err)
// os.Exit(1)
// }
// return decrypted
//}
//
//func loadCerts() {
// var err error
// certBytes, err := os.ReadFile(config.GetAsString("Crypto.cert_path"))
// keyBytes, err := os.ReadFile(config.GetAsString("Crypto.key_path"))
// if err != nil {
// fmt.Println("Error reading cert or key,", err)
// os.Exit(1)
// }
//
// cert, err = x509.ParseCertificate(certBytes)
// if err != nil {
// fmt.Println("Error parsing certificate,", err)
// os.Exit(1)
// }
// key, err = x509.ParsePKCS1PrivateKey(keyBytes)
// if err != nil {
// fmt.Println("Error parsing private key,", err)
// }
//}
// 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 DecryptFileXChaCha(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)
}
in, err := os.ReadFile(inPath)
if err != nil {
return fmt.Errorf("read input: %w", err)
}
if len(in) < chacha20poly1305.NonceSizeX {
return errors.New("ciphertext too short")
}
nonce := in[:chacha20poly1305.NonceSizeX]
ciphertext := in[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
}