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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package internal
import (
const secretSize = 256 // Bytes
// The interface for storing secrets and their associated blessings.
type AgentStorage interface {
// Get retrieves the blessings associated with secret. It returns an
// error if the secret doesn't exist.
Get(secret string) (blessings security.Blessings, err error)
// Put stores the blessings and associates them with secret. It
// returns an error if the secret already exists.
Put(secret string, blessings security.Blessings) (err error)
// Delete deletes the secret and its associated blessings. It returns
// an error is there was a problem deleting the secret.
Delete(secret string) error
func NewAgent(principal security.Principal, storage AgentStorage) *ClusterAgent {
return &ClusterAgent{principal, storage}
// The Cluster Agent keeps a list of Secret Keys and Blessings associated with
// them. It issues new Blessings when presented with a valid Secret Key. The new
// Blessings are extensions of the Blessings associated with the Secret Key.
type ClusterAgent struct {
principal security.Principal
storage AgentStorage
// NewSecret creates a new secret key and associates it with the given
// blessings. The blessings must be bound to the principal of the Cluster
// Agent.
func (a *ClusterAgent) NewSecret(blessings security.Blessings) (string, error) {
if !reflect.DeepEqual(a.principal.PublicKey(), blessings.PublicKey()) {
return "", verror.New(verror.ErrBadArg, nil, "blessings bound to wrong PublicKey")
rawSecret := make([]byte, secretSize)
if _, err := rand.Read(rawSecret); err != nil {
return "", err
secret := hex.EncodeToString(rawSecret)
if err :=, blessings); err != nil {
return "", err
return secret, nil
// ForgetSecret forgets the secret key and its associated blessings.
func (a *ClusterAgent) ForgetSecret(secret string) error {
// Bless creates new blessing extensions using the blessings associated with the
// given secret key.
func (a *ClusterAgent) Bless(secret string, publicKey security.PublicKey, name string) (security.Blessings, error) {
blessings, err :=
if err != nil {
return blessings, err
// blessings was provided to the ClusterAgent via NewSecret and
// any caveats should have been placed by the caller of NewSecret.
// The ClusterAgent itself is simply re-delegating its authority to the
// possessor of 'secret'.
return a.principal.Bless(publicKey, blessings, name, security.UnconstrainedUse())