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package key
import (
crypto_rand "crypto/rand"
"errors"
"fmt"
"os"
"path/filepath"
"github.com/adrg/xdg"
"golang.org/x/crypto/nacl/box"
)
var (
pubKeyFile = filepath.Join(xdg.DataHome, "hose", "pubkey")
pubKeyFileMode os.FileMode = 0644
privKeyFile = filepath.Join(xdg.DataHome, "hose", "privkey")
privKeyFileMode os.FileMode = 0600
)
// Generate generates a new public/private keypair. It stores the private key in the
// private key file and the public key in the public key file. If either of the key
// files already exist, they will not be overwritten; instead an error will be returned.
func Generate() error {
// Create public key file.
pubFile, err := createFile(pubKeyFile, pubKeyFileMode)
if err != nil {
return err
}
defer pubFile.Close()
// Create private key file.
privFile, err := createFile(privKeyFile, privKeyFileMode)
if err != nil {
pubFile.Close()
_ = os.Remove(pubKeyFile)
return err
}
defer privFile.Close()
// Generate keypair.
pubkey, privkey, err := box.GenerateKey(crypto_rand.Reader)
if err != nil {
return err
}
// Write keypair to files.
if _, err := pubFile.Write((*pubkey)[:]); err != nil {
return err
}
if _, err := privFile.Write((*privkey)[:]); err != nil {
return err
}
return nil
}
// createFile creates a file with the specified permissions and returns it for writing.
// It does not truncate an existing file. If the file already exists, an error is returned.
func createFile(name string, mode os.FileMode) (*os.File, error) {
exists, err := fileExists(name)
if err != nil {
return nil, err // unexpected error.
} else if exists {
return nil, errFileExists(name) // file exists; do not overwrite.
}
// Does not exist; continue;
f, err := os.Create(name)
if err != nil {
return nil, err
}
if err := f.Chmod(mode); err != nil {
f.Close()
_ = os.Remove(name)
return nil, err
}
return f, nil
}
// fileExists returns a nil error and true/false if a file does/doesn't exist.
// If an error is encountered, a non-nil error is returned.
func fileExists(path string) (bool, error) {
_, err := os.Stat(path)
if errors.Is(err, os.ErrNotExist) {
return false, nil // file doesn't exist.
} else if err != nil {
return false, err // unexpected error.
}
return true, nil // file exists.
}
// errFileExists constructs a 'file already exists' error message.
func errFileExists(path string) error {
return fmt.Errorf("%s: %s", os.ErrExist, path)
}
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