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keycache.go
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keycache.go
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// Package keycache provides the ability to hold active keys in memory
// for the Red October server.
//
// Copyright (c) 2013 CloudFlare, Inc.
package keycache
import (
"crypto/aes"
"crypto/ecdsa"
"crypto/rand"
"crypto/rsa"
"crypto/sha1"
"crypto/x509"
"errors"
"fmt"
"log"
"strings"
"sync"
"time"
"github.com/cloudflare/redoctober/ecdh"
"github.com/cloudflare/redoctober/passvault"
)
// DelegateIndex is used to index the map of currently delegated keys.
// This is necessary to provide a way for a delegator to provide multiple
// delegations. It is also used to avoid the complexity of string parsing
// and enforcement of username and slot character requirements.
type DelegateIndex struct {
Name string
Slot string
}
// Usage holds the permissions of a delegated permission
type Usage struct {
Uses int // Number of uses delegated
Labels []string // File labels allowed to decrypt
Users []string // Set of users allows to decrypt
Expiry time.Time // Expiration of usage
}
// ActiveUser holds the information about an actively delegated key.
type ActiveUser struct {
Usage
AltNames map[string]string
Admin bool
Type string
Key []byte
rsaKey rsa.PrivateKey
eccKey *ecdsa.PrivateKey
}
// Cache represents the current list of delegated keys in memory
type Cache struct {
lock *sync.Mutex
UserKeys map[DelegateIndex]ActiveUser
}
// matchesLabel returns true if this usage applies the user and label
// an empty array of Users indicates that all users are valid
func (usage Usage) matchesLabel(labels []string) bool {
// if asset has no labels always match
if len(labels) == 0 {
return true
}
for _, validLabel := range usage.Labels {
for _, label := range labels {
if label == validLabel {
return true
}
}
}
return false
}
// matches returns true if this usage applies the user and label
// an empty array of Users indicates that all users are valid
func (usage Usage) matches(user string, labels []string) bool {
if !usage.matchesLabel(labels) {
return false
}
// if usage lists no users, always match
if len(usage.Users) == 0 {
return true
}
for _, validUser := range usage.Users {
if user == validUser {
return true
}
}
return false
}
// NewCache initalizes a new cache.
func NewCache() Cache {
return Cache{
UserKeys: make(map[DelegateIndex]ActiveUser),
lock: new(sync.Mutex),
}
}
// NewFrom takes the output of GetSummary and returns a new keycache.
func NewFrom(summary map[string]ActiveUser) *Cache {
cache := &Cache{
UserKeys: make(map[DelegateIndex]ActiveUser),
lock: new(sync.Mutex),
}
for di, user := range summary {
diSplit := strings.SplitN(di, "-", 2)
index := DelegateIndex{
Name: diSplit[0],
}
if len(diSplit) == 2 {
index.Slot = diSplit[1]
}
cache.UserKeys[index] = user
}
return cache
}
// setUser takes an ActiveUser and adds it to the cache.
func (cache *Cache) setUser(in ActiveUser, name, slot string) {
cache.lock.Lock()
cache.UserKeys[DelegateIndex{Name: name, Slot: slot}] = in
cache.lock.Unlock()
}
// Valid returns true if matching active user is present.
func (cache *Cache) Valid(name, user string, labels []string) (present bool) {
for d, key := range cache.UserKeys {
if d.Name != name {
continue
}
if key.Usage.matches(user, labels) {
return true
}
}
return false
}
// MatchUser returns the matching active user if present
// and a boolean to indicate its presence.
func (cache *Cache) MatchUser(name, user string, labels []string) (ActiveUser, string, bool) {
var key ActiveUser
for d, key := range cache.UserKeys {
if d.Name != name {
continue
}
if key.Usage.matches(user, labels) {
return key, d.Slot, true
}
}
return key, "", false
}
// useKey decrements the counter on an active key
// for decryption or symmetric encryption
func (cache *Cache) useKey(name, user, slot string, labels []string) {
if val, slot, present := cache.MatchUser(name, user, labels); present {
val.Usage.Uses--
if val.Usage.Uses <= 0 {
delete(cache.UserKeys, DelegateIndex{name, slot})
} else {
cache.setUser(val, name, slot)
}
}
}
// GetSummary returns the list of active user keys.
func (cache *Cache) GetSummary() map[string]ActiveUser {
summaryData := make(map[string]ActiveUser)
for d, activeUser := range cache.UserKeys {
summaryInfo := d.Name
if d.Slot != "" {
summaryInfo = fmt.Sprintf("%s-%s", d.Name, d.Slot)
}
summaryData[summaryInfo] = activeUser
}
return summaryData
}
// Flush removes all delegated keys. It returns true if the cache
// wasn't empty (i.e. there were active users removed), and false if
// the cache was empty.
func (cache *Cache) Flush() bool {
if len(cache.UserKeys) == 0 {
return false
}
cache.lock.Lock()
for d := range cache.UserKeys {
delete(cache.UserKeys, d)
}
cache.lock.Unlock()
return true
}
// Refresh purges all expired keys. It returns the number of
// delegations that were removed.
func (cache *Cache) Refresh() int {
var removed int
for d, active := range cache.UserKeys {
if active.Usage.Expiry.Before(time.Now()) {
log.Println("Record expired", d.Name, d.Slot, active.Usage.Users, active.Usage.Labels, active.Usage.Expiry)
removed++
delete(cache.UserKeys, d)
}
}
return removed
}
// AddKeyFromRecord decrypts a key for a given record and adds it to the cache.
func (cache *Cache) AddKeyFromRecord(record passvault.PasswordRecord, name, password string, users, labels []string, uses int, slot, durationString string) (err error) {
var current ActiveUser
cache.Refresh()
// compute exipiration
duration, err := time.ParseDuration(durationString)
if err != nil {
return
}
current.Usage.Uses = uses
current.Usage.Expiry = time.Now().Add(duration)
current.Usage.Users = users
current.Usage.Labels = labels
// get decryption keys
switch record.Type {
case passvault.RSARecord:
current.rsaKey, err = record.GetKeyRSA(password)
if err != nil {
return
}
current.Key = x509.MarshalPKCS1PrivateKey(¤t.rsaKey)
case passvault.ECCRecord:
current.eccKey, err = record.GetKeyECC(password)
if err != nil {
return
}
current.Key, err = x509.MarshalECPrivateKey(current.eccKey)
default:
err = errors.New("Unknown record type")
}
if err != nil {
return
}
// set types
current.Type = record.Type
current.Admin = record.Admin
// add current to map (overwriting previous for this name)
cache.setUser(current, name, slot)
return
}
// DecryptKey decrypts a 16 byte key using the key corresponding to the name parameter
// For RSA and EC keys, the cached RSA/EC key is used to decrypt
// the pubEncryptedKey which is then used to decrypt the input
// buffer.
func (cache *Cache) DecryptKey(in []byte, name, user string, labels []string, pubEncryptedKey []byte) (out []byte, err error) {
cache.Refresh()
decryptKey, slot, ok := cache.MatchUser(name, user, labels)
if !ok {
return nil, errors.New("Key not delegated")
}
var aesKey []byte
// pick the aesKey to use for decryption
switch decryptKey.Type {
case passvault.RSARecord:
// extract the aes key from the pubEncryptedKey
aesKey, err = rsa.DecryptOAEP(sha1.New(), rand.Reader, &decryptKey.rsaKey, pubEncryptedKey, nil)
if err != nil {
return out, err
}
case passvault.ECCRecord:
// extract the aes key from the pubEncryptedKey
aesKey, err = ecdh.Decrypt(decryptKey.eccKey, pubEncryptedKey)
if err != nil {
return out, err
}
default:
return nil, errors.New("unknown type")
}
// decrypt
aesSession, err := aes.NewCipher(aesKey)
if err != nil {
return out, err
}
out = make([]byte, 16)
aesSession.Decrypt(out, in)
cache.useKey(name, user, slot, labels)
return
}
// DecryptShares decrypts an array of 16 byte shares using the key corresponding
// to the name parameter.
func (cache *Cache) DecryptShares(in [][]byte, name, user string, labels []string, pubEncryptedKey []byte) (out [][]byte, err error) {
cache.Refresh()
decryptKey, slot, ok := cache.MatchUser(name, user, labels)
if !ok {
return nil, errors.New("Key not delegated")
}
var aesKey []byte
// pick the aesKey to use for decryption
switch decryptKey.Type {
case passvault.RSARecord:
// extract the aes key from the pubEncryptedKey
aesKey, err = rsa.DecryptOAEP(sha1.New(), rand.Reader, &decryptKey.rsaKey, pubEncryptedKey, nil)
if err != nil {
return
}
case passvault.ECCRecord:
// extract the aes key from the pubEncryptedKey
aesKey, err = ecdh.Decrypt(decryptKey.eccKey, pubEncryptedKey)
if err != nil {
return
}
default:
return nil, errors.New("unknown type")
}
// decrypt
aesSession, err := aes.NewCipher(aesKey)
if err != nil {
return
}
for _, encShare := range in {
tmp := make([]byte, 16)
aesSession.Decrypt(tmp, encShare)
out = append(out, tmp)
}
cache.useKey(name, user, slot, labels)
return
}
// DelegateStatus will return a list of admins who have delegated to a particular user, for a particular label.
// This is useful information to have when determining the status of an order and conveying order progress.
func (cache *Cache) DelegateStatus(name string, labels, admins []string) (adminsDelegated []string, hasDelegated int) {
// Iterate over the admins of the ciphertext to look for users
// who have already delegated the label to the delegatee.
for _, admin := range admins {
for di, use := range cache.UserKeys {
if di.Name != admin {
continue
}
nameFound := false
for _, user := range use.Users {
if user == name {
nameFound = true
}
}
for _, ol := range use.Labels {
for _, il := range labels {
if ol == il {
if nameFound {
adminsDelegated = append(adminsDelegated, admin)
hasDelegated++
}
}
}
}
}
}
return
}
// Restore unmarshals the private key stored in the delegator to the
// appropriate private structure.
func (cache *Cache) Restore() (err error) {
for index, uk := range cache.UserKeys {
if len(uk.Key) == 0 {
return errors.New("keycache: no private key in active user")
}
rsaPriv, err := x509.ParsePKCS1PrivateKey(uk.Key)
if err == nil {
uk.rsaKey = *rsaPriv
cache.UserKeys[index] = uk
continue
}
ecPriv, err := x509.ParseECPrivateKey(uk.Key)
if err == nil {
uk.eccKey = ecPriv
cache.UserKeys[index] = uk
continue
}
return err
}
return nil
}