mirror of
https://codeberg.org/forgejo/forgejo.git
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275 lines
6.2 KiB
Go
275 lines
6.2 KiB
Go
// Copyright 2023 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package chef
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import (
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"context"
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"crypto"
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"crypto/rsa"
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"crypto/sha1"
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"crypto/x509"
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"encoding/base64"
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"encoding/pem"
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"fmt"
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"hash"
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"math/big"
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"net/http"
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"path"
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"regexp"
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"slices"
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"strconv"
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"strings"
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"time"
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user_model "code.gitea.io/gitea/models/user"
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chef_module "code.gitea.io/gitea/modules/packages/chef"
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"code.gitea.io/gitea/modules/util"
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"code.gitea.io/gitea/services/auth"
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"github.com/minio/sha256-simd"
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)
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const (
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maxTimeDifference = 10 * time.Minute
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)
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var (
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algorithmPattern = regexp.MustCompile(`algorithm=(\w+)`)
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versionPattern = regexp.MustCompile(`version=(\d+\.\d+)`)
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authorizationPattern = regexp.MustCompile(`\AX-Ops-Authorization-(\d+)`)
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_ auth.Method = &Auth{}
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)
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// Documentation:
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// https://docs.chef.io/server/api_chef_server/#required-headers
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// https://github.com/chef-boneyard/chef-rfc/blob/master/rfc065-sign-v1.3.md
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// https://github.com/chef/mixlib-authentication/blob/bc8adbef833d4be23dc78cb23e6fe44b51ebc34f/lib/mixlib/authentication/signedheaderauth.rb
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type Auth struct{}
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func (a *Auth) Name() string {
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return "chef"
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}
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// Verify extracts the user from the signed request
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// If the request is signed with the user private key the user is verified.
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func (a *Auth) Verify(req *http.Request, w http.ResponseWriter, store auth.DataStore, sess auth.SessionStore) (*user_model.User, error) {
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u, err := getUserFromRequest(req)
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if err != nil {
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return nil, err
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}
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if u == nil {
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return nil, nil
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}
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pub, err := getUserPublicKey(req.Context(), u)
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if err != nil {
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return nil, err
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}
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if err := verifyTimestamp(req); err != nil {
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return nil, err
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}
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version, err := getSignVersion(req)
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if err != nil {
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return nil, err
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}
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if err := verifySignedHeaders(req, version, pub.(*rsa.PublicKey)); err != nil {
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return nil, err
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}
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return u, nil
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}
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func getUserFromRequest(req *http.Request) (*user_model.User, error) {
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username := req.Header.Get("X-Ops-Userid")
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if username == "" {
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return nil, nil
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}
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return user_model.GetUserByName(req.Context(), username)
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}
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func getUserPublicKey(ctx context.Context, u *user_model.User) (crypto.PublicKey, error) {
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pubKey, err := user_model.GetSetting(ctx, u.ID, chef_module.SettingPublicPem)
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if err != nil {
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return nil, err
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}
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pubPem, _ := pem.Decode([]byte(pubKey))
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return x509.ParsePKIXPublicKey(pubPem.Bytes)
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}
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func verifyTimestamp(req *http.Request) error {
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hdr := req.Header.Get("X-Ops-Timestamp")
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if hdr == "" {
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return util.NewInvalidArgumentErrorf("X-Ops-Timestamp header missing")
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}
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ts, err := time.Parse(time.RFC3339, hdr)
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if err != nil {
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return err
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}
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diff := time.Now().UTC().Sub(ts)
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if diff < 0 {
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diff = -diff
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}
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if diff > maxTimeDifference {
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return fmt.Errorf("time difference")
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}
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return nil
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}
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func getSignVersion(req *http.Request) (string, error) {
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hdr := req.Header.Get("X-Ops-Sign")
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if hdr == "" {
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return "", util.NewInvalidArgumentErrorf("X-Ops-Sign header missing")
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}
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m := versionPattern.FindStringSubmatch(hdr)
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if len(m) != 2 {
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return "", util.NewInvalidArgumentErrorf("invalid X-Ops-Sign header")
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}
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switch m[1] {
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case "1.0", "1.1", "1.2", "1.3":
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default:
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return "", util.NewInvalidArgumentErrorf("unsupported version")
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}
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version := m[1]
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m = algorithmPattern.FindStringSubmatch(hdr)
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if len(m) == 2 && m[1] != "sha1" && !(m[1] == "sha256" && version == "1.3") {
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return "", util.NewInvalidArgumentErrorf("unsupported algorithm")
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}
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return version, nil
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}
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func verifySignedHeaders(req *http.Request, version string, pub *rsa.PublicKey) error {
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authorizationData, err := getAuthorizationData(req)
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if err != nil {
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return err
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}
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checkData := buildCheckData(req, version)
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switch version {
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case "1.3":
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return verifyDataNew(authorizationData, checkData, pub, crypto.SHA256)
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case "1.2":
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return verifyDataNew(authorizationData, checkData, pub, crypto.SHA1)
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default:
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return verifyDataOld(authorizationData, checkData, pub)
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}
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}
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func getAuthorizationData(req *http.Request) ([]byte, error) {
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valueList := make(map[int]string)
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for k, vs := range req.Header {
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if m := authorizationPattern.FindStringSubmatch(k); m != nil {
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index, _ := strconv.Atoi(m[1])
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var v string
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if len(vs) == 0 {
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v = ""
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} else {
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v = vs[0]
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}
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valueList[index] = v
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}
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}
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tmp := make([]string, len(valueList))
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for k, v := range valueList {
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if k > len(tmp) {
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return nil, fmt.Errorf("invalid X-Ops-Authorization headers")
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}
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tmp[k-1] = v
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}
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return base64.StdEncoding.DecodeString(strings.Join(tmp, ""))
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}
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func buildCheckData(req *http.Request, version string) []byte {
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username := req.Header.Get("X-Ops-Userid")
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if version != "1.0" && version != "1.3" {
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sum := sha1.Sum([]byte(username))
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username = base64.StdEncoding.EncodeToString(sum[:])
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}
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var data string
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if version == "1.3" {
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data = fmt.Sprintf(
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"Method:%s\nPath:%s\nX-Ops-Content-Hash:%s\nX-Ops-Sign:version=%s\nX-Ops-Timestamp:%s\nX-Ops-UserId:%s\nX-Ops-Server-API-Version:%s",
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req.Method,
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path.Clean(req.URL.Path),
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req.Header.Get("X-Ops-Content-Hash"),
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version,
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req.Header.Get("X-Ops-Timestamp"),
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username,
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req.Header.Get("X-Ops-Server-Api-Version"),
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)
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} else {
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sum := sha1.Sum([]byte(path.Clean(req.URL.Path)))
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data = fmt.Sprintf(
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"Method:%s\nHashed Path:%s\nX-Ops-Content-Hash:%s\nX-Ops-Timestamp:%s\nX-Ops-UserId:%s",
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req.Method,
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base64.StdEncoding.EncodeToString(sum[:]),
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req.Header.Get("X-Ops-Content-Hash"),
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req.Header.Get("X-Ops-Timestamp"),
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username,
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)
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}
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return []byte(data)
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}
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func verifyDataNew(signature, data []byte, pub *rsa.PublicKey, algo crypto.Hash) error {
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var h hash.Hash
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if algo == crypto.SHA256 {
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h = sha256.New()
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} else {
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h = sha1.New()
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}
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if _, err := h.Write(data); err != nil {
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return err
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}
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return rsa.VerifyPKCS1v15(pub, algo, h.Sum(nil), signature)
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}
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func verifyDataOld(signature, data []byte, pub *rsa.PublicKey) error {
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c := new(big.Int)
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m := new(big.Int)
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m.SetBytes(signature)
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e := big.NewInt(int64(pub.E))
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c.Exp(m, e, pub.N)
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out := c.Bytes()
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skip := 0
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for i := 2; i < len(out); i++ {
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if i+1 >= len(out) {
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break
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}
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if out[i] == 0xFF && out[i+1] == 0 {
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skip = i + 2
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break
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}
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}
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if !slices.Equal(out[skip:], data) {
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return fmt.Errorf("could not verify signature")
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}
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return nil
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}
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