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