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engine.go
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engine.go
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package engine
import (
"bytes"
"crypto/md5"
"errors"
"fmt"
"io"
"log"
"strings"
"time"
"filippo.io/age"
"filippo.io/age/armor"
)
// SecretAuditAction
type SecretAuditAction struct {
Action string
Performer string
Key string
CreatedDate time.Time
}
type Secret struct {
Key string
Value string
Performer string
PublicKeyIds []string
CreatedDate time.Time
ModifiedDate time.Time
}
// AgeSecretEncryptionEngine a library for encrypting secrets using age encryption
type AgeSecretEncryptionEngine struct {
identity age.Identity
identityPubHash string
recipients []age.Recipient
recipientPubHashes []string
auditHandler func(audit SecretAuditAction) error
readHandler func(reason, key string) (s Secret, err error)
areThereUnDecryptableSecretsHandler func(key string) (bool, error)
saveHandler func(secret Secret) error
removeHandler func(key string) error
initialized bool
}
// New initializes a new AgeSecretEncryptionEngine.
func New() *AgeSecretEncryptionEngine {
return &AgeSecretEncryptionEngine{}
}
// AddDecryptionKey this is your most secret of key. This is the one that will be used to retrieve the encrypted contents
func (e *AgeSecretEncryptionEngine) AddDecryptionKey(privateKey string) error {
identity, err := age.ParseX25519Identity(privateKey)
if err != nil {
log.Fatalf("Failed to parse private key: %v", err)
return errors.New("failed to parse private key")
}
iPublicKey := identity.Recipient().String()
public_key_hash := md5.Sum([]byte(iPublicKey))
e.identity = identity
e.identityPubHash = fmt.Sprintf("%x", public_key_hash)
return nil
}
// AddEncryptionKeys this is your list of public keys that will be used to encrypt with. Be sure you provide more than 3 and include the public key for your private key. Store the private keys not being used somewhere safe in case you need to rotate the key
func (e *AgeSecretEncryptionEngine) AddEncryptionKeys(publicKeys []string) error {
for _, key := range publicKeys {
recipient, err := age.ParseX25519Recipient(key)
if err != nil {
return err
}
recipient_key_hash := md5.Sum([]byte(recipient.String()))
e.recipientPubHashes = append(e.recipientPubHashes, fmt.Sprintf("%x", recipient_key_hash))
e.recipients = append(e.recipients, recipient)
}
return nil
}
func (e *AgeSecretEncryptionEngine) Start() error {
// This is to ensure can rotate out privateKeys and recover data
if len(e.recipients) < 3 {
return errors.New("at least 3 publicKeys required")
}
if e.identityPubHash == "" {
return errors.New("a private key is required for operation")
}
iPublicKeyIncluded := false
for _, h := range e.recipientPubHashes {
if h == e.identityPubHash {
iPublicKeyIncluded = true
}
}
// Ensures the public key for the private key is included
if !iPublicKeyIncluded {
return errors.New("must include public key for chosen privatekey")
}
if e.saveHandler == nil {
return errors.New("must register a save handler")
}
if e.auditHandler == nil {
return errors.New("must register an audit handler")
}
if e.readHandler == nil {
return errors.New("must register a read handler")
}
if e.removeHandler == nil {
return errors.New("must register a remove handler")
}
if e.areThereUnDecryptableSecretsHandler == nil {
return errors.New("must register a handler to check for undecryptable secrets")
}
unDecryptable, err := e.areThereUnDecryptableSecretsHandler(e.identityPubHash)
if err != nil {
return err
}
if unDecryptable {
return errors.New("there are secrets encrypted that your private key can't decrypt")
}
e.initialized = true
return nil
}
// RegisterAuditHandler registers the audit handler which will be executed before every Encrypt / Decrypt so its clear who and what touched data and when
func (e *AgeSecretEncryptionEngine) RegisterAuditHandler(f func(audit SecretAuditAction) error) {
e.auditHandler = f
}
// RegisterReadHandler registers the read handler which will be used by the engine to retrieve secrets using your logic to talk to your db provider
func (e *AgeSecretEncryptionEngine) RegisterReadHandler(f func(key string) (s Secret, err error)) {
// Wrap read handler with our own to make sure we log every read we do
e.readHandler = func(method, key string) (Secret, error) {
if err := e.auditHandler(SecretAuditAction{Performer: fmt.Sprintf("age-secret-encryption-engine-%s", method), Action: "read", Key: key}); err != nil {
return Secret{}, err
}
return f(key)
}
}
// RegisterAreThereUnDecryptableSecretsHandler registers a handler to check if there are any secrets that aren't encrypted using the public key for current secret key.
func (e *AgeSecretEncryptionEngine) RegisterAreThereUnDecryptableSecretsHandler(f func(key string) (bool, error)) {
e.areThereUnDecryptableSecretsHandler = f
}
// RegisterSaveHandler registers the save handler which will be used by the engine to save secrets using your logic to talk to your db provider
func (e *AgeSecretEncryptionEngine) RegisterSaveHandler(f func(s Secret) error) {
e.saveHandler = f
}
// RegisterRemoveHandler registers the remove handler which will be used by the engine to rmove secrets using your logic to talk to your db provider
func (e *AgeSecretEncryptionEngine) RegisterRemoveHandler(f func(key string) error) {
e.removeHandler = f
}
// StoreSecret Encrypts the secret using age and saves using your save handler
func (e *AgeSecretEncryptionEngine) StoreSecret(performer, key, body string) error {
if !e.initialized {
return errors.New("engine not started")
}
// Audit step must always be executed before we even let it encrypt
if err := e.auditHandler(SecretAuditAction{Performer: performer, Action: "encrypt", Key: key}); err != nil {
return err
}
out := &bytes.Buffer{}
w, err := age.Encrypt(out, e.recipients...)
if err != nil {
return err
}
if _, err := io.WriteString(w, body); err != nil {
return err
}
if err := w.Close(); err != nil {
return err
}
if err := e.saveHandler(Secret{Performer: performer, PublicKeyIds: e.recipientPubHashes, Key: key, Value: out.String()}); err != nil {
return err
}
return nil
}
// RetrieveSecret Fetches the secret using your read handler and decrypts it using age
func (e *AgeSecretEncryptionEngine) RetrieveSecret(performer, key string) (decryptedSecret string, err error) {
if !e.initialized {
return "", errors.New("engine not started")
}
// Audit step must always be executed before we even let it do anything
if err := e.auditHandler(SecretAuditAction{Performer: performer, Action: "decrypt", Key: key}); err != nil {
return "", err
}
secret, err := e.readHandler("decrypt-method", key)
if err != nil {
return "", err
}
r, err := age.Decrypt(strings.NewReader(secret.Value), e.identity)
if err != nil {
return "", err
}
out := &bytes.Buffer{}
if _, err := io.Copy(out, r); err != nil {
return "", err
}
return out.String(), nil
}
// RemoveSecret removes secret using the remove handler
func (e *AgeSecretEncryptionEngine) RemoveSecret(performer, key string) error {
if !e.initialized {
return errors.New("engine not started")
}
// Audit step must always be executed before we even let it do anything
if err := e.auditHandler(SecretAuditAction{Performer: performer, Action: "remove", Key: key}); err != nil {
return err
}
if err := e.removeHandler(key); err != nil {
return err
}
return nil
}
// GetArmoredSecret Retrieves secret using read handler and returns an armored copy of it
func (e *AgeSecretEncryptionEngine) GetArmoredSecret(performer, key string) (armoredSecret string, err error) {
if !e.initialized {
return "", errors.New("engine not started")
}
// Audit step must always be executed before we even let it do anything
if err := e.auditHandler(SecretAuditAction{Performer: performer, Action: "armoring", Key: key}); err != nil {
return "", err
}
secret, err := e.readHandler("get-armored-secret-method", key)
if err != nil {
return "", err
}
out := &bytes.Buffer{}
armorWriter := armor.NewWriter(out)
if _, err := io.Copy(armorWriter, strings.NewReader(secret.Value)); err != nil {
return "", err
}
if err := armorWriter.Close(); err != nil {
return "", err
}
return out.String(), nil
}
// Unexported for use of validating armoring
func (e *AgeSecretEncryptionEngine) decryptArmoredSecret(body string) (decryptedSecret string, err error) {
out := &bytes.Buffer{}
f := strings.NewReader(body)
armorReader := armor.NewReader(f)
r, err := age.Decrypt(armorReader, e.identity)
if err != nil {
return "", err
}
if _, err := io.Copy(out, r); err != nil {
return "", err
}
fmt.Printf("File contents: %q\n", out.Bytes())
return out.String(), nil
}