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act.go
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act.go
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package api
import (
"context"
"crypto/ecdsa"
"crypto/rand"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"io"
"strings"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/ecies"
"github.com/ethereum/go-ethereum/swarm/log"
"github.com/ethereum/go-ethereum/swarm/sctx"
"github.com/ethereum/go-ethereum/swarm/storage"
"golang.org/x/crypto/scrypt"
"golang.org/x/crypto/sha3"
cli "gopkg.in/urfave/cli.v1"
)
var (
ErrDecrypt = errors.New("cant decrypt - forbidden")
ErrUnknownAccessType = errors.New("unknown access type (or not implemented)")
ErrDecryptDomainForbidden = errors.New("decryption request domain forbidden - can only decrypt on localhost")
AllowedDecryptDomains = []string{
"localhost",
"127.0.0.1",
}
)
const EMPTY_CREDENTIALS = ""
type AccessEntry struct {
Type AccessType
Publisher string
Salt []byte
Act string
KdfParams *KdfParams
}
type DecryptFunc func(*ManifestEntry) error
func (a *AccessEntry) MarshalJSON() (out []byte, err error) {
return json.Marshal(struct {
Type AccessType `json:"type,omitempty"`
Publisher string `json:"publisher,omitempty"`
Salt string `json:"salt,omitempty"`
Act string `json:"act,omitempty"`
KdfParams *KdfParams `json:"kdf_params,omitempty"`
}{
Type: a.Type,
Publisher: a.Publisher,
Salt: hex.EncodeToString(a.Salt),
Act: a.Act,
KdfParams: a.KdfParams,
})
}
func (a *AccessEntry) UnmarshalJSON(value []byte) error {
v := struct {
Type AccessType `json:"type,omitempty"`
Publisher string `json:"publisher,omitempty"`
Salt string `json:"salt,omitempty"`
Act string `json:"act,omitempty"`
KdfParams *KdfParams `json:"kdf_params,omitempty"`
}{}
err := json.Unmarshal(value, &v)
if err != nil {
return err
}
a.Act = v.Act
a.KdfParams = v.KdfParams
a.Publisher = v.Publisher
a.Salt, err = hex.DecodeString(v.Salt)
if err != nil {
return err
}
if len(a.Salt) != 32 {
return errors.New("salt should be 32 bytes long")
}
a.Type = v.Type
return nil
}
type KdfParams struct {
N int `json:"n"`
P int `json:"p"`
R int `json:"r"`
}
type AccessType string
const AccessTypePass = AccessType("pass")
const AccessTypePK = AccessType("pk")
const AccessTypeACT = AccessType("act")
// NewAccessEntryPassword creates a manifest AccessEntry in order to create an ACT protected by a password
func NewAccessEntryPassword(salt []byte, kdfParams *KdfParams) (*AccessEntry, error) {
if len(salt) != 32 {
return nil, fmt.Errorf("salt should be 32 bytes long")
}
return &AccessEntry{
Type: AccessTypePass,
Salt: salt,
KdfParams: kdfParams,
}, nil
}
// NewAccessEntryPK creates a manifest AccessEntry in order to create an ACT protected by a pair of Elliptic Curve keys
func NewAccessEntryPK(publisher string, salt []byte) (*AccessEntry, error) {
if len(publisher) != 66 {
return nil, fmt.Errorf("publisher should be 66 characters long, got %d", len(publisher))
}
if len(salt) != 32 {
return nil, fmt.Errorf("salt should be 32 bytes long")
}
return &AccessEntry{
Type: AccessTypePK,
Publisher: publisher,
Salt: salt,
}, nil
}
// NewAccessEntryACT creates a manifest AccessEntry in order to create an ACT protected by a combination of EC keys and passwords
func NewAccessEntryACT(publisher string, salt []byte, act string) (*AccessEntry, error) {
if len(salt) != 32 {
return nil, fmt.Errorf("salt should be 32 bytes long")
}
if len(publisher) != 66 {
return nil, fmt.Errorf("publisher should be 66 characters long")
}
return &AccessEntry{
Type: AccessTypeACT,
Publisher: publisher,
Salt: salt,
Act: act,
KdfParams: DefaultKdfParams,
}, nil
}
// NOOPDecrypt is a generic decrypt function that is passed into the API in places where real ACT decryption capabilities are
// either unwanted, or alternatively, cannot be implemented in the immediate scope
func NOOPDecrypt(*ManifestEntry) error {
return nil
}
var DefaultKdfParams = NewKdfParams(262144, 1, 8)
// NewKdfParams returns a KdfParams struct with the given scrypt params
func NewKdfParams(n, p, r int) *KdfParams {
return &KdfParams{
N: n,
P: p,
R: r,
}
}
// NewSessionKeyPassword creates a session key based on a shared secret (password) and the given salt
// and kdf parameters in the access entry
func NewSessionKeyPassword(password string, accessEntry *AccessEntry) ([]byte, error) {
if accessEntry.Type != AccessTypePass && accessEntry.Type != AccessTypeACT {
return nil, errors.New("incorrect access entry type")
}
return sessionKeyPassword(password, accessEntry.Salt, accessEntry.KdfParams)
}
func sessionKeyPassword(password string, salt []byte, kdfParams *KdfParams) ([]byte, error) {
return scrypt.Key(
[]byte(password),
salt,
kdfParams.N,
kdfParams.R,
kdfParams.P,
32,
)
}
// NewSessionKeyPK creates a new ACT Session Key using an ECDH shared secret for the given key pair and the given salt value
func NewSessionKeyPK(private *ecdsa.PrivateKey, public *ecdsa.PublicKey, salt []byte) ([]byte, error) {
granteePubEcies := ecies.ImportECDSAPublic(public)
privateKey := ecies.ImportECDSA(private)
bytes, err := privateKey.GenerateShared(granteePubEcies, 16, 16)
if err != nil {
return nil, err
}
bytes = append(salt, bytes...)
sessionKey := crypto.Keccak256(bytes)
return sessionKey, nil
}
func (a *API) doDecrypt(ctx context.Context, credentials string, pk *ecdsa.PrivateKey) DecryptFunc {
return func(m *ManifestEntry) error {
if m.Access == nil {
return nil
}
allowed := false
requestDomain := sctx.GetHost(ctx)
for _, v := range AllowedDecryptDomains {
if strings.Contains(requestDomain, v) {
allowed = true
}
}
if !allowed {
return ErrDecryptDomainForbidden
}
switch m.Access.Type {
case "pass":
if credentials != "" {
key, err := NewSessionKeyPassword(credentials, m.Access)
if err != nil {
return err
}
ref, err := hex.DecodeString(m.Hash)
if err != nil {
return err
}
enc := NewRefEncryption(len(ref) - 8)
decodedRef, err := enc.Decrypt(ref, key)
if err != nil {
return ErrDecrypt
}
m.Hash = hex.EncodeToString(decodedRef)
m.Access = nil
return nil
}
return ErrDecrypt
case "pk":
publisherBytes, err := hex.DecodeString(m.Access.Publisher)
if err != nil {
return ErrDecrypt
}
publisher, err := crypto.DecompressPubkey(publisherBytes)
if err != nil {
return ErrDecrypt
}
key, err := NewSessionKeyPK(pk, publisher, m.Access.Salt)
if err != nil {
return ErrDecrypt
}
ref, err := hex.DecodeString(m.Hash)
if err != nil {
return err
}
enc := NewRefEncryption(len(ref) - 8)
decodedRef, err := enc.Decrypt(ref, key)
if err != nil {
return ErrDecrypt
}
m.Hash = hex.EncodeToString(decodedRef)
m.Access = nil
return nil
case "act":
var (
sessionKey []byte
err error
)
publisherBytes, err := hex.DecodeString(m.Access.Publisher)
if err != nil {
return ErrDecrypt
}
publisher, err := crypto.DecompressPubkey(publisherBytes)
if err != nil {
return ErrDecrypt
}
sessionKey, err = NewSessionKeyPK(pk, publisher, m.Access.Salt)
if err != nil {
return ErrDecrypt
}
found, ciphertext, decryptionKey, err := a.getACTDecryptionKey(ctx, storage.Address(common.Hex2Bytes(m.Access.Act)), sessionKey)
if err != nil {
return err
}
if !found {
// try to fall back to password
if credentials != "" {
sessionKey, err = NewSessionKeyPassword(credentials, m.Access)
if err != nil {
return err
}
found, ciphertext, decryptionKey, err = a.getACTDecryptionKey(ctx, storage.Address(common.Hex2Bytes(m.Access.Act)), sessionKey)
if err != nil {
return err
}
if !found {
return ErrDecrypt
}
} else {
return ErrDecrypt
}
}
enc := NewRefEncryption(len(ciphertext) - 8)
decodedRef, err := enc.Decrypt(ciphertext, decryptionKey)
if err != nil {
return ErrDecrypt
}
ref, err := hex.DecodeString(m.Hash)
if err != nil {
return err
}
enc = NewRefEncryption(len(ref) - 8)
decodedMainRef, err := enc.Decrypt(ref, decodedRef)
if err != nil {
return ErrDecrypt
}
m.Hash = hex.EncodeToString(decodedMainRef)
m.Access = nil
return nil
}
return ErrUnknownAccessType
}
}
func (a *API) getACTDecryptionKey(ctx context.Context, actManifestAddress storage.Address, sessionKey []byte) (found bool, ciphertext, decryptionKey []byte, err error) {
hasher := sha3.NewLegacyKeccak256()
hasher.Write(append(sessionKey, 0))
lookupKey := hasher.Sum(nil)
hasher.Reset()
hasher.Write(append(sessionKey, 1))
accessKeyDecryptionKey := hasher.Sum(nil)
hasher.Reset()
lk := hex.EncodeToString(lookupKey)
list, err := a.GetManifestList(ctx, NOOPDecrypt, actManifestAddress, lk)
if err != nil {
return false, nil, nil, err
}
for _, v := range list.Entries {
if v.Path == lk {
cipherTextBytes, err := hex.DecodeString(v.Hash)
if err != nil {
return false, nil, nil, err
}
return true, cipherTextBytes, accessKeyDecryptionKey, nil
}
}
return false, nil, nil, nil
}
func GenerateAccessControlManifest(ctx *cli.Context, ref string, accessKey []byte, ae *AccessEntry) (*Manifest, error) {
refBytes, err := hex.DecodeString(ref)
if err != nil {
return nil, err
}
// encrypt ref with accessKey
enc := NewRefEncryption(len(refBytes))
encrypted, err := enc.Encrypt(refBytes, accessKey)
if err != nil {
return nil, err
}
m := &Manifest{
Entries: []ManifestEntry{
{
Hash: hex.EncodeToString(encrypted),
ContentType: ManifestType,
ModTime: time.Now(),
Access: ae,
},
},
}
return m, nil
}
// DoPK is a helper function to the CLI API that handles the entire business logic for
// creating a session key and access entry given the cli context, ec keys and salt
func DoPK(ctx *cli.Context, privateKey *ecdsa.PrivateKey, granteePublicKey string, salt []byte) (sessionKey []byte, ae *AccessEntry, err error) {
if granteePublicKey == "" {
return nil, nil, errors.New("need a grantee Public Key")
}
b, err := hex.DecodeString(granteePublicKey)
if err != nil {
log.Error("error decoding grantee public key", "err", err)
return nil, nil, err
}
granteePub, err := crypto.DecompressPubkey(b)
if err != nil {
log.Error("error decompressing grantee public key", "err", err)
return nil, nil, err
}
sessionKey, err = NewSessionKeyPK(privateKey, granteePub, salt)
if err != nil {
log.Error("error getting session key", "err", err)
return nil, nil, err
}
ae, err = NewAccessEntryPK(hex.EncodeToString(crypto.CompressPubkey(&privateKey.PublicKey)), salt)
if err != nil {
log.Error("error generating access entry", "err", err)
return nil, nil, err
}
return sessionKey, ae, nil
}
// DoACT is a helper function to the CLI API that handles the entire business logic for
// creating a access key, access entry and ACT manifest (including uploading it) given the cli context, ec keys, password grantees and salt
func DoACT(ctx *cli.Context, privateKey *ecdsa.PrivateKey, salt []byte, grantees []string, encryptPasswords []string) (accessKey []byte, ae *AccessEntry, actManifest *Manifest, err error) {
if len(grantees) == 0 && len(encryptPasswords) == 0 {
return nil, nil, nil, errors.New("did not get any grantee public keys or any encryption passwords")
}
publisherPub := hex.EncodeToString(crypto.CompressPubkey(&privateKey.PublicKey))
grantees = append(grantees, publisherPub)
accessKey = make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, salt); err != nil {
panic("reading from crypto/rand failed: " + err.Error())
}
if _, err := io.ReadFull(rand.Reader, accessKey); err != nil {
panic("reading from crypto/rand failed: " + err.Error())
}
lookupPathEncryptedAccessKeyMap := make(map[string]string)
i := 0
for _, v := range grantees {
i++
if v == "" {
return nil, nil, nil, errors.New("need a grantee Public Key")
}
b, err := hex.DecodeString(v)
if err != nil {
log.Error("error decoding grantee public key", "err", err)
return nil, nil, nil, err
}
granteePub, err := crypto.DecompressPubkey(b)
if err != nil {
log.Error("error decompressing grantee public key", "err", err)
return nil, nil, nil, err
}
sessionKey, err := NewSessionKeyPK(privateKey, granteePub, salt)
if err != nil {
return nil, nil, nil, err
}
hasher := sha3.NewLegacyKeccak256()
hasher.Write(append(sessionKey, 0))
lookupKey := hasher.Sum(nil)
hasher.Reset()
hasher.Write(append(sessionKey, 1))
accessKeyEncryptionKey := hasher.Sum(nil)
enc := NewRefEncryption(len(accessKey))
encryptedAccessKey, err := enc.Encrypt(accessKey, accessKeyEncryptionKey)
if err != nil {
return nil, nil, nil, err
}
lookupPathEncryptedAccessKeyMap[hex.EncodeToString(lookupKey)] = hex.EncodeToString(encryptedAccessKey)
}
for _, pass := range encryptPasswords {
sessionKey, err := sessionKeyPassword(pass, salt, DefaultKdfParams)
if err != nil {
return nil, nil, nil, err
}
hasher := sha3.NewLegacyKeccak256()
hasher.Write(append(sessionKey, 0))
lookupKey := hasher.Sum(nil)
hasher.Reset()
hasher.Write(append(sessionKey, 1))
accessKeyEncryptionKey := hasher.Sum(nil)
enc := NewRefEncryption(len(accessKey))
encryptedAccessKey, err := enc.Encrypt(accessKey, accessKeyEncryptionKey)
if err != nil {
return nil, nil, nil, err
}
lookupPathEncryptedAccessKeyMap[hex.EncodeToString(lookupKey)] = hex.EncodeToString(encryptedAccessKey)
}
m := &Manifest{
Entries: []ManifestEntry{},
}
for k, v := range lookupPathEncryptedAccessKeyMap {
m.Entries = append(m.Entries, ManifestEntry{
Path: k,
Hash: v,
ContentType: "text/plain",
})
}
ae, err = NewAccessEntryACT(hex.EncodeToString(crypto.CompressPubkey(&privateKey.PublicKey)), salt, "")
if err != nil {
return nil, nil, nil, err
}
return accessKey, ae, m, nil
}
// DoPassword is a helper function to the CLI API that handles the entire business logic for
// creating a session key and an access entry given the cli context, password and salt.
// By default - DefaultKdfParams are used as the scrypt params
func DoPassword(ctx *cli.Context, password string, salt []byte) (sessionKey []byte, ae *AccessEntry, err error) {
ae, err = NewAccessEntryPassword(salt, DefaultKdfParams)
if err != nil {
return nil, nil, err
}
sessionKey, err = NewSessionKeyPassword(password, ae)
if err != nil {
return nil, nil, err
}
return sessionKey, ae, nil
}