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|
// Package profile stores the optional VFace identity in an age-encrypted vault.
package profile
import (
"bytes"
"crypto/ed25519"
"crypto/rand"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"time"
"aegis/internal/cryptokit"
"filippo.io/age"
agearmor "filippo.io/age/armor"
)
const (
Version = 1
MinPasswordLength = 12
maxVaultBytes = 1 << 20
)
type Profile struct {
Version int `json:"version"`
Username string `json:"username"`
Email string `json:"email"`
PublicKey string `json:"ed25519_public_key"`
PrivateKey string `json:"ed25519_private_key"`
AgeIdentity string `json:"age_identity,omitempty"`
YubiKeyFingerprint string `json:"yubikey_signing_fingerprint,omitempty"`
CreatedAt time.Time `json:"created_at"`
}
func DefaultPath() (string, error) {
directory, err := os.UserConfigDir()
if err != nil {
return "", fmt.Errorf("locate profile directory: %w", err)
}
return filepath.Join(directory, "aegis", "profile.json.age"), nil
}
func Generate(username, email string) (Profile, error) {
username = strings.TrimSpace(username)
email = strings.TrimSpace(email)
if username == "" || email == "" {
return Profile{}, errors.New("VFace username and email are required")
}
if strings.ContainsAny(username+email, "\x00\r\n|") {
return Profile{}, errors.New("VFace username and email contain forbidden characters")
}
publicKey, privateKey, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
return Profile{}, fmt.Errorf("generate VFace Ed25519 key pair: %w", err)
}
return Profile{
Version: Version,
Username: username,
Email: email,
PublicKey: base64.StdEncoding.EncodeToString(publicKey),
PrivateKey: base64.StdEncoding.EncodeToString(privateKey),
CreatedAt: time.Now().UTC(),
}, nil
}
func Save(path string, value Profile, password string) error {
if err := validatePassword(password); err != nil {
return err
}
if err := Validate(value); err != nil {
return err
}
plaintext, err := json.MarshalIndent(value, "", " ")
if err != nil {
return fmt.Errorf("encode VFace profile: %w", err)
}
recipient, err := age.NewScryptRecipient(password)
if err != nil {
return fmt.Errorf("create profile password recipient: %w", err)
}
var encrypted bytes.Buffer
armor := agearmor.NewWriter(&encrypted)
writer, err := age.Encrypt(armor, recipient)
if err != nil {
_ = armor.Close()
return fmt.Errorf("create profile vault: %w", err)
}
if _, err := writer.Write(plaintext); err != nil {
_ = writer.Close()
_ = armor.Close()
return fmt.Errorf("write profile vault: %w", err)
}
if err := writer.Close(); err != nil {
_ = armor.Close()
return fmt.Errorf("close profile vault: %w", err)
}
if err := armor.Close(); err != nil {
return fmt.Errorf("close profile armor: %w", err)
}
return atomicWrite(path, encrypted.Bytes())
}
func Load(path string, password string) (Profile, error) {
if err := validatePassword(password); err != nil {
return Profile{}, err
}
ciphertext, err := os.ReadFile(path)
if err != nil {
return Profile{}, fmt.Errorf("read profile vault: %w", err)
}
if len(ciphertext) > maxVaultBytes {
return Profile{}, errors.New("profile vault is too large")
}
identity, err := age.NewScryptIdentity(password)
if err != nil {
return Profile{}, fmt.Errorf("create profile password identity: %w", err)
}
reader, err := age.Decrypt(agearmor.NewReader(bytes.NewReader(ciphertext)), identity)
if err != nil {
return Profile{}, errors.New("cannot unlock profile vault")
}
plaintext, err := io.ReadAll(io.LimitReader(reader, maxVaultBytes+1))
if err != nil {
return Profile{}, fmt.Errorf("read profile vault: %w", err)
}
if len(plaintext) > maxVaultBytes {
return Profile{}, errors.New("profile vault contents are too large")
}
var value Profile
if err := json.Unmarshal(plaintext, &value); err != nil {
return Profile{}, errors.New("profile vault contains invalid data")
}
if err := Validate(value); err != nil {
return Profile{}, fmt.Errorf("validate profile vault: %w", err)
}
return value, nil
}
func Validate(value Profile) error {
if value.Version != Version {
return fmt.Errorf("unsupported VFace profile version %d", value.Version)
}
if value.Username == "" || value.Email == "" || strings.ContainsAny(value.Username+value.Email, "\x00\r\n|") {
return errors.New("invalid VFace username or email")
}
publicKey, err := decodePublicKey(value.PublicKey)
if err != nil {
return err
}
if strings.TrimSpace(value.PrivateKey) == "" {
if strings.TrimSpace(value.YubiKeyFingerprint) == "" {
return errors.New("profile needs an encrypted private key or a YubiKey signing fingerprint")
}
return nil
}
privateKey, err := decodePrivateKey(value.PrivateKey)
if err != nil {
return err
}
derived := privateKey.Public().(ed25519.PublicKey)
if !bytes.Equal(publicKey, derived) {
return errors.New("VFace public and private keys do not match")
}
return nil
}
func validatePassword(password string) error {
if len([]rune(password)) < MinPasswordLength {
return fmt.Errorf("profile password must contain at least %d characters", MinPasswordLength)
}
return nil
}
func decodePublicKey(value string) (ed25519.PublicKey, error) {
canonical, err := cryptokit.CanonicalEd25519PublicKey(value)
if err != nil {
return nil, fmt.Errorf("invalid VFace public key: %w", err)
}
decoded, err := base64.StdEncoding.DecodeString(canonical)
if err != nil {
return nil, errors.New("invalid VFace public key encoding")
}
return ed25519.PublicKey(decoded), nil
}
func decodePrivateKey(value string) (ed25519.PrivateKey, error) {
decoded, err := base64.StdEncoding.DecodeString(strings.TrimSpace(value))
if err != nil || len(decoded) != ed25519.PrivateKeySize {
return nil, errors.New("invalid VFace private key")
}
return ed25519.PrivateKey(decoded), nil
}
func atomicWrite(path string, data []byte) error {
if path == "" {
return errors.New("profile vault path is required")
}
directory := filepath.Dir(path)
if err := os.MkdirAll(directory, 0o700); err != nil {
return fmt.Errorf("create profile directory: %w", err)
}
if err := os.Chmod(directory, 0o700); err != nil {
return fmt.Errorf("protect profile directory: %w", err)
}
temporary, err := os.CreateTemp(directory, ".profile-*.tmp")
if err != nil {
return fmt.Errorf("create profile temporary file: %w", err)
}
temporaryName := temporary.Name()
defer os.Remove(temporaryName)
if err := temporary.Chmod(0o600); err != nil {
_ = temporary.Close()
return err
}
if _, err := temporary.Write(data); err != nil {
_ = temporary.Close()
return fmt.Errorf("write profile vault: %w", err)
}
if err := temporary.Sync(); err != nil {
_ = temporary.Close()
return fmt.Errorf("sync profile vault: %w", err)
}
if err := temporary.Close(); err != nil {
return err
}
if err := os.Rename(temporaryName, path); err != nil {
return fmt.Errorf("commit profile vault: %w", err)
}
return nil
}
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