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types.go
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types.go
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package data
import (
"crypto/sha256"
"crypto/sha512"
"crypto/subtle"
"encoding/hex"
"fmt"
"hash"
"io"
"io/ioutil"
"strings"
"time"
"github.com/Sirupsen/logrus"
"github.com/docker/go/canonical/json"
"github.com/docker/notary"
)
// SigAlgorithm for types of signatures
type SigAlgorithm string
func (k SigAlgorithm) String() string {
return string(k)
}
const defaultHashAlgorithm = "sha256"
// Signature types
const (
EDDSASignature SigAlgorithm = "eddsa"
RSAPSSSignature SigAlgorithm = "rsapss"
RSAPKCS1v15Signature SigAlgorithm = "rsapkcs1v15"
ECDSASignature SigAlgorithm = "ecdsa"
PyCryptoSignature SigAlgorithm = "pycrypto-pkcs#1 pss"
)
// Key types
const (
ED25519Key = "ed25519"
RSAKey = "rsa"
RSAx509Key = "rsa-x509"
ECDSAKey = "ecdsa"
ECDSAx509Key = "ecdsa-x509"
)
// TUFTypes is the set of metadata types
var TUFTypes = map[string]string{
CanonicalRootRole: "Root",
CanonicalTargetsRole: "Targets",
CanonicalSnapshotRole: "Snapshot",
CanonicalTimestampRole: "Timestamp",
}
// SetTUFTypes allows one to override some or all of the default
// type names in TUF.
func SetTUFTypes(ts map[string]string) {
for k, v := range ts {
TUFTypes[k] = v
}
}
// ValidTUFType checks if the given type is valid for the role
func ValidTUFType(typ, role string) bool {
if ValidRole(role) {
// All targets delegation roles must have
// the valid type is for targets.
if role == "" {
// role is unknown and does not map to
// a type
return false
}
if strings.HasPrefix(role, CanonicalTargetsRole+"/") {
role = CanonicalTargetsRole
}
}
// most people will just use the defaults so have this optimal check
// first. Do comparison just in case there is some unknown vulnerability
// if a key and value in the map differ.
if v, ok := TUFTypes[role]; ok {
return typ == v
}
return false
}
// Signed is the high level, partially deserialized metadata object
// used to verify signatures before fully unpacking, or to add signatures
// before fully packing
type Signed struct {
Signed *json.RawMessage `json:"signed"`
Signatures []Signature `json:"signatures"`
}
// SignedCommon contains the fields common to the Signed component of all
// TUF metadata files
type SignedCommon struct {
Type string `json:"_type"`
Expires time.Time `json:"expires"`
Version int `json:"version"`
}
// SignedMeta is used in server validation where we only need signatures
// and common fields
type SignedMeta struct {
Signed SignedCommon `json:"signed"`
Signatures []Signature `json:"signatures"`
}
// Signature is a signature on a piece of metadata
type Signature struct {
KeyID string `json:"keyid"`
Method SigAlgorithm `json:"method"`
Signature []byte `json:"sig"`
IsValid bool `json:"-"`
}
// Files is the map of paths to file meta container in targets and delegations
// metadata files
type Files map[string]FileMeta
// Hashes is the map of hash type to digest created for each metadata
// and target file
type Hashes map[string][]byte
// NotaryDefaultHashes contains the default supported hash algorithms.
var NotaryDefaultHashes = []string{notary.SHA256, notary.SHA512}
// FileMeta contains the size and hashes for a metadata or target file. Custom
// data can be optionally added.
type FileMeta struct {
Length int64 `json:"length"`
Hashes Hashes `json:"hashes"`
Custom *json.RawMessage `json:"custom,omitempty"`
}
// CheckHashes verifies all the checksums specified by the "hashes" of the payload.
func CheckHashes(payload []byte, name string, hashes Hashes) error {
cnt := 0
// k, v indicate the hash algorithm and the corresponding value
for k, v := range hashes {
switch k {
case notary.SHA256:
checksum := sha256.Sum256(payload)
if subtle.ConstantTimeCompare(checksum[:], v) == 0 {
return ErrMismatchedChecksum{alg: notary.SHA256, name: name, expected: hex.EncodeToString(v)}
}
cnt++
case notary.SHA512:
checksum := sha512.Sum512(payload)
if subtle.ConstantTimeCompare(checksum[:], v) == 0 {
return ErrMismatchedChecksum{alg: notary.SHA512, name: name, expected: hex.EncodeToString(v)}
}
cnt++
}
}
if cnt == 0 {
return ErrMissingMeta{Role: name}
}
return nil
}
// CompareMultiHashes verifies that the two Hashes passed in can represent the same data.
// This means that both maps must have at least one key defined for which they map, and no conflicts.
// Note that we check the intersection of map keys, which adds support for non-default hash algorithms in notary
func CompareMultiHashes(hashes1, hashes2 Hashes) error {
// First check if the two hash structures are valid
if err := CheckValidHashStructures(hashes1); err != nil {
return err
}
if err := CheckValidHashStructures(hashes2); err != nil {
return err
}
// Check if they have at least one matching hash, and no conflicts
cnt := 0
for hashAlg, hash1 := range hashes1 {
hash2, ok := hashes2[hashAlg]
if !ok {
continue
}
if subtle.ConstantTimeCompare(hash1[:], hash2[:]) == 0 {
return fmt.Errorf("mismatched %s checksum", hashAlg)
}
// If we reached here, we had a match
cnt++
}
if cnt == 0 {
return fmt.Errorf("at least one matching hash needed")
}
return nil
}
// CheckValidHashStructures returns an error, or nil, depending on whether
// the content of the hashes is valid or not.
func CheckValidHashStructures(hashes Hashes) error {
cnt := 0
for k, v := range hashes {
switch k {
case notary.SHA256:
if len(v) != sha256.Size {
return ErrInvalidChecksum{alg: notary.SHA256}
}
cnt++
case notary.SHA512:
if len(v) != sha512.Size {
return ErrInvalidChecksum{alg: notary.SHA512}
}
cnt++
}
}
if cnt == 0 {
return fmt.Errorf("at least one supported hash needed")
}
return nil
}
// NewFileMeta generates a FileMeta object from the reader, using the
// hash algorithms provided
func NewFileMeta(r io.Reader, hashAlgorithms ...string) (FileMeta, error) {
if len(hashAlgorithms) == 0 {
hashAlgorithms = []string{defaultHashAlgorithm}
}
hashes := make(map[string]hash.Hash, len(hashAlgorithms))
for _, hashAlgorithm := range hashAlgorithms {
var h hash.Hash
switch hashAlgorithm {
case notary.SHA256:
h = sha256.New()
case notary.SHA512:
h = sha512.New()
default:
return FileMeta{}, fmt.Errorf("Unknown hash algorithm: %s", hashAlgorithm)
}
hashes[hashAlgorithm] = h
r = io.TeeReader(r, h)
}
n, err := io.Copy(ioutil.Discard, r)
if err != nil {
return FileMeta{}, err
}
m := FileMeta{Length: n, Hashes: make(Hashes, len(hashes))}
for hashAlgorithm, h := range hashes {
m.Hashes[hashAlgorithm] = h.Sum(nil)
}
return m, nil
}
// Delegations holds a tier of targets delegations
type Delegations struct {
Keys Keys `json:"keys"`
Roles []*Role `json:"roles"`
}
// NewDelegations initializes an empty Delegations object
func NewDelegations() *Delegations {
return &Delegations{
Keys: make(map[string]PublicKey),
Roles: make([]*Role, 0),
}
}
// These values are recommended TUF expiry times.
var defaultExpiryTimes = map[string]time.Duration{
CanonicalRootRole: notary.Year,
CanonicalTargetsRole: 90 * notary.Day,
CanonicalSnapshotRole: 7 * notary.Day,
CanonicalTimestampRole: notary.Day,
}
// SetDefaultExpiryTimes allows one to change the default expiries.
func SetDefaultExpiryTimes(times map[string]time.Duration) {
for key, value := range times {
if _, ok := defaultExpiryTimes[key]; !ok {
logrus.Errorf("Attempted to set default expiry for an unknown role: %s", key)
continue
}
defaultExpiryTimes[key] = value
}
}
// DefaultExpires gets the default expiry time for the given role
func DefaultExpires(role string) time.Time {
if d, ok := defaultExpiryTimes[role]; ok {
return time.Now().Add(d)
}
var t time.Time
return t.UTC().Round(time.Second)
}
type unmarshalledSignature Signature
// UnmarshalJSON does a custom unmarshalling of the signature JSON
func (s *Signature) UnmarshalJSON(data []byte) error {
uSignature := unmarshalledSignature{}
err := json.Unmarshal(data, &uSignature)
if err != nil {
return err
}
uSignature.Method = SigAlgorithm(strings.ToLower(string(uSignature.Method)))
*s = Signature(uSignature)
return nil
}