From 653ceee9ee623dd62cd958cf4eb9318452d00424 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@harshavardhana.net>
Date: Sun, 21 Feb 2016 17:57:05 -0800
Subject: [PATCH] signV4: Move pkg/signature to pkg/s3/signature4

Cleanup and move this to relevant path.
---
 auth-handler.go                               | 77 ++++++++++++++-
 bucket-handlers.go                            |  6 +-
 pkg/fs/fs-multipart.go                        |  6 +-
 pkg/fs/fs-object.go                           |  6 +-
 .../errors.go => s3/signature4/v4-errors.go}  |  7 +-
 pkg/{signature => s3/signature4}/v4-parser.go | 59 ++++++++----
 .../signature4/v4-postpolicyform.go}          |  2 +-
 .../signature4/v4-signature.go}               | 73 +++++++-------
 .../utils.go => s3/signature4/v4-utils.go}    | 24 +++--
 pkg/xl/bucket.go                              |  4 +-
 pkg/xl/interfaces.go                          | 10 +-
 pkg/xl/multipart.go                           | 10 +-
 pkg/xl/xl-v1.go                               |  8 +-
 pkg/xl/xl-v2.go                               |  8 +-
 routers.go                                    |  6 +-
 signature.go                                  | 94 -------------------
 16 files changed, 210 insertions(+), 190 deletions(-)
 rename pkg/{signature/errors.go => s3/signature4/v4-errors.go} (91%)
 rename pkg/{signature => s3/signature4}/v4-parser.go (72%)
 rename pkg/{signature/postpolicyform.go => s3/signature4/v4-postpolicyform.go} (99%)
 rename pkg/{signature/signature-v4.go => s3/signature4/v4-signature.go} (81%)
 rename pkg/{signature/utils.go => s3/signature4/v4-utils.go} (84%)
 delete mode 100644 signature.go

diff --git a/auth-handler.go b/auth-handler.go
index f47131822..dc7fc73cf 100644
--- a/auth-handler.go
+++ b/auth-handler.go
@@ -16,13 +16,88 @@
 
 package main
 
-import "net/http"
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"net/http"
+	"strings"
+
+	"github.com/minio/minio/pkg/s3/signature4"
+)
 
 const (
 	signV4Algorithm = "AWS4-HMAC-SHA256"
 	jwtAlgorithm    = "Bearer"
 )
 
+// Verify if request has JWT.
+func isRequestJWT(r *http.Request) bool {
+	if _, ok := r.Header["Authorization"]; ok {
+		if strings.HasPrefix(r.Header.Get("Authorization"), jwtAlgorithm) {
+			return true
+		}
+	}
+	return false
+}
+
+// Verify if request has AWS Signature Version '4'.
+func isRequestSignatureV4(r *http.Request) bool {
+	if _, ok := r.Header["Authorization"]; ok {
+		if strings.HasPrefix(r.Header.Get("Authorization"), signV4Algorithm) {
+			return true
+		}
+	}
+	return false
+}
+
+// Verify if request has AWS Presignature Version '4'.
+func isRequestPresignedSignatureV4(r *http.Request) bool {
+	if _, ok := r.URL.Query()["X-Amz-Credential"]; ok {
+		return true
+	}
+	return false
+}
+
+// Verify if request has AWS Post policy Signature Version '4'.
+func isRequestPostPolicySignatureV4(r *http.Request) bool {
+	if _, ok := r.Header["Content-Type"]; ok {
+		if strings.Contains(r.Header.Get("Content-Type"), "multipart/form-data") {
+			return true
+		}
+	}
+	return false
+}
+
+// Verify if request requires ACL check.
+func isRequestRequiresACLCheck(r *http.Request) bool {
+	if isRequestSignatureV4(r) || isRequestPresignedSignatureV4(r) || isRequestPostPolicySignatureV4(r) {
+		return false
+	}
+	return true
+}
+
+// Verify if request has valid AWS Signature Version '4'.
+func isSignV4ReqAuthenticated(sign *signature4.Sign, r *http.Request) bool {
+	auth := sign.SetHTTPRequestToVerify(r)
+	if isRequestSignatureV4(r) {
+		dummyPayload := sha256.Sum256([]byte(""))
+		ok, err := auth.DoesSignatureMatch(hex.EncodeToString(dummyPayload[:]))
+		if err != nil {
+			errorIf(err.Trace(), "Signature verification failed.", nil)
+			return false
+		}
+		return ok
+	} else if isRequestPresignedSignatureV4(r) {
+		ok, err := auth.DoesPresignedSignatureMatch()
+		if err != nil {
+			errorIf(err.Trace(), "Presigned signature verification failed.", nil)
+			return false
+		}
+		return ok
+	}
+	return false
+}
+
 // authHandler - handles all the incoming authorization headers and
 // validates them if possible.
 type authHandler struct {
diff --git a/bucket-handlers.go b/bucket-handlers.go
index 2103d1799..89587fcaf 100644
--- a/bucket-handlers.go
+++ b/bucket-handlers.go
@@ -24,11 +24,11 @@ import (
 	"mime/multipart"
 	"net/http"
 
-	"github.com/gorilla/mux"
+	mux "github.com/gorilla/mux"
 	"github.com/minio/minio/pkg/crypto/sha256"
 	"github.com/minio/minio/pkg/fs"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 )
 
 // GetBucketLocationHandler - GET Bucket location.
@@ -368,7 +368,7 @@ func (api storageAPI) PostPolicyBucketHandler(w http.ResponseWriter, r *http.Req
 		writeErrorResponse(w, r, SignatureDoesNotMatch, r.URL.Path)
 		return
 	}
-	if err = signV4.ApplyPolicyCond(formValues); err != nil {
+	if err = signature4.ApplyPolicyCond(formValues); err != nil {
 		errorIf(err.Trace(), "Invalid request, policy doesn't match with the endpoint.", nil)
 		writeErrorResponse(w, r, MalformedPOSTRequest, r.URL.Path)
 		return
diff --git a/pkg/fs/fs-multipart.go b/pkg/fs/fs-multipart.go
index a7f51631b..7d9199d11 100644
--- a/pkg/fs/fs-multipart.go
+++ b/pkg/fs/fs-multipart.go
@@ -39,7 +39,7 @@ import (
 	"github.com/minio/minio/pkg/disk"
 	"github.com/minio/minio/pkg/mimedb"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 )
 
 // isValidUploadID - is upload id.
@@ -297,7 +297,7 @@ func (a partNumber) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 func (a partNumber) Less(i, j int) bool { return a[i].PartNumber < a[j].PartNumber }
 
 // CreateObjectPart - create a part in a multipart session
-func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum string, partID int, size int64, data io.Reader, signature *signV4.Signature) (string, *probe.Error) {
+func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum string, partID int, size int64, data io.Reader, signature *signature4.Sign) (string, *probe.Error) {
 	di, err := disk.GetInfo(fs.path)
 	if err != nil {
 		return "", probe.NewError(err)
@@ -431,7 +431,7 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 }
 
 // CompleteMultipartUpload - complete a multipart upload and persist the data
-func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, data io.Reader, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, data io.Reader, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	// Check bucket name is valid.
 	if !IsValidBucketName(bucket) {
 		return ObjectMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
diff --git a/pkg/fs/fs-object.go b/pkg/fs/fs-object.go
index bb9cc123b..27368b55f 100644
--- a/pkg/fs/fs-object.go
+++ b/pkg/fs/fs-object.go
@@ -34,7 +34,7 @@ import (
 	"github.com/minio/minio/pkg/ioutils"
 	"github.com/minio/minio/pkg/mimedb"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 )
 
 /// Object Operations
@@ -199,7 +199,7 @@ func isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) bool {
 }
 
 // CreateObject - create an object.
-func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size int64, data io.Reader, sig *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size int64, data io.Reader, sig *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	di, e := disk.GetInfo(fs.path)
 	if e != nil {
 		return ObjectMetadata{}, probe.NewError(e)
@@ -294,7 +294,7 @@ func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size in
 		}
 		if !ok {
 			file.CloseAndPurge()
-			return ObjectMetadata{}, signV4.ErrSignDoesNotMath("Signature does not match")
+			return ObjectMetadata{}, probe.NewError(SignDoesNotMatch{})
 		}
 	}
 	file.Close()
diff --git a/pkg/signature/errors.go b/pkg/s3/signature4/v4-errors.go
similarity index 91%
rename from pkg/signature/errors.go
rename to pkg/s3/signature4/v4-errors.go
index 58aaea2e9..cbc8792df 100644
--- a/pkg/signature/errors.go
+++ b/pkg/s3/signature4/v4-errors.go
@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package signature
+package signature4
 
 import (
 	"fmt"
@@ -24,13 +24,14 @@ import (
 
 type errFunc func(msg string, a ...string) *probe.Error
 
+// generic error factory which wraps around probe.NewError()
 func errFactory() errFunc {
 	return func(msg string, a ...string) *probe.Error {
 		return probe.NewError(fmt.Errorf("%s, Args: %s", msg, a)).Untrace()
 	}
 }
 
-// Various errors.
+// Various signature v4 errors.
 var (
 	ErrPolicyAlreadyExpired  = errFactory()
 	ErrInvalidRegion         = errFactory()
diff --git a/pkg/signature/v4-parser.go b/pkg/s3/signature4/v4-parser.go
similarity index 72%
rename from pkg/signature/v4-parser.go
rename to pkg/s3/signature4/v4-parser.go
index 64c3deb1a..0674b5807 100644
--- a/pkg/signature/v4-parser.go
+++ b/pkg/s3/signature4/v4-parser.go
@@ -1,4 +1,20 @@
-package signature
+/*
+ * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package signature4
 
 import (
 	"net/url"
@@ -8,7 +24,9 @@ import (
 	"github.com/minio/minio/pkg/probe"
 )
 
-type credScope struct {
+// credential data type represents structured form of Credential
+// string from authorization header.
+type credential struct {
 	accessKeyID string
 	scope       struct {
 		date    time.Time
@@ -18,45 +36,46 @@ type credScope struct {
 	}
 }
 
-func parseCredential(credElement string) (credScope, *probe.Error) {
+// parse credential string into its structured form.
+func parseCredential(credElement string) (credential, *probe.Error) {
 	creds := strings.Split(strings.TrimSpace(credElement), "=")
 	if len(creds) != 2 {
-		return credScope{}, ErrMissingFields("Credential tag has missing fields.", credElement).Trace(credElement)
+		return credential{}, ErrMissingFields("Credential tag has missing fields.", credElement).Trace(credElement)
 	}
 	if creds[0] != "Credential" {
-		return credScope{}, ErrMissingCredTag("Missing credentials tag.", credElement).Trace(credElement)
+		return credential{}, ErrMissingCredTag("Missing credentials tag.", credElement).Trace(credElement)
 	}
 	credElements := strings.Split(strings.TrimSpace(creds[1]), "/")
 	if len(credElements) != 5 {
-		return credScope{}, ErrCredMalformed("Credential values malformed.", credElement).Trace(credElement)
+		return credential{}, ErrCredMalformed("Credential values malformed.", credElement).Trace(credElement)
 	}
 	if !isValidAccessKey.MatchString(credElements[0]) {
-		return credScope{}, ErrInvalidAccessKeyID("Invalid access key id.", credElement).Trace(credElement)
+		return credential{}, ErrInvalidAccessKeyID("Invalid access key id.", credElement).Trace(credElement)
 	}
-	cred := credScope{
+	cred := credential{
 		accessKeyID: credElements[0],
 	}
 	var e error
 	cred.scope.date, e = time.Parse(yyyymmdd, credElements[1])
 	if e != nil {
-		return credScope{}, ErrInvalidDateFormat("Invalid date format.", credElement).Trace(credElement)
+		return credential{}, ErrInvalidDateFormat("Invalid date format.", credElement).Trace(credElement)
 	}
 	if credElements[2] == "" {
-		return credScope{}, ErrRegionISEmpty("Region is empty.", credElement).Trace(credElement)
+		return credential{}, ErrRegionISEmpty("Region is empty.", credElement).Trace(credElement)
 	}
 	cred.scope.region = credElements[2]
 	if credElements[3] != "s3" {
-		return credScope{}, ErrInvalidService("Invalid service detected.", credElement).Trace(credElement)
+		return credential{}, ErrInvalidService("Invalid service detected.", credElement).Trace(credElement)
 	}
 	cred.scope.service = credElements[3]
 	if credElements[4] != "aws4_request" {
-		return credScope{}, ErrInvalidRequestVersion("Invalid request version detected.", credElement).Trace(credElement)
+		return credential{}, ErrInvalidRequestVersion("Invalid request version detected.", credElement).Trace(credElement)
 	}
 	cred.scope.request = credElements[4]
 	return cred, nil
 }
 
-// parse signature.
+// Parse signature string.
 func parseSignature(signElement string) (string, *probe.Error) {
 	signFields := strings.Split(strings.TrimSpace(signElement), "=")
 	if len(signFields) != 2 {
@@ -69,7 +88,7 @@ func parseSignature(signElement string) (string, *probe.Error) {
 	return signature, nil
 }
 
-// parse signed headers.
+// Parse signed headers string.
 func parseSignedHeaders(signedHdrElement string) ([]string, *probe.Error) {
 	signedHdrFields := strings.Split(strings.TrimSpace(signedHdrElement), "=")
 	if len(signedHdrFields) != 2 {
@@ -82,14 +101,14 @@ func parseSignedHeaders(signedHdrElement string) ([]string, *probe.Error) {
 	return signedHeaders, nil
 }
 
-// structured version of AWS Signature V4 header.
+// signValues data type represents structured form of AWS Signature V4 header.
 type signValues struct {
-	Creds         credScope
+	Credential    credential
 	SignedHeaders []string
 	Signature     string
 }
 
-// structued version of AWS Signature V4 query string.
+// preSignValues data type represents structued form of AWS Signature V4 query string.
 type preSignValues struct {
 	signValues
 	Date    time.Time
@@ -115,8 +134,8 @@ func parsePreSignV4(query url.Values) (preSignValues, *probe.Error) {
 	preSignV4Values := preSignValues{}
 
 	var err *probe.Error
-	// Save credentail values.
-	preSignV4Values.Creds, err = parseCredential("Credential=" + query.Get("X-Amz-Credential"))
+	// Save credential.
+	preSignV4Values.Credential, err = parseCredential("Credential=" + query.Get("X-Amz-Credential"))
 	if err != nil {
 		return preSignValues{}, err.Trace(query.Get("X-Amz-Credential"))
 	}
@@ -181,7 +200,7 @@ func parseSignV4(v4Auth string) (signValues, *probe.Error) {
 
 	var err *probe.Error
 	// Save credentail values.
-	signV4Values.Creds, err = parseCredential(authFields[0])
+	signV4Values.Credential, err = parseCredential(authFields[0])
 	if err != nil {
 		return signValues{}, err.Trace(v4Auth)
 	}
diff --git a/pkg/signature/postpolicyform.go b/pkg/s3/signature4/v4-postpolicyform.go
similarity index 99%
rename from pkg/signature/postpolicyform.go
rename to pkg/s3/signature4/v4-postpolicyform.go
index 006c6d848..47247a433 100644
--- a/pkg/signature/postpolicyform.go
+++ b/pkg/s3/signature4/v4-postpolicyform.go
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package signature
+package signature4
 
 import (
 	"encoding/base64"
diff --git a/pkg/signature/signature-v4.go b/pkg/s3/signature4/v4-signature.go
similarity index 81%
rename from pkg/signature/signature-v4.go
rename to pkg/s3/signature4/v4-signature.go
index 624722cf4..36ebcbcd8 100644
--- a/pkg/signature/signature-v4.go
+++ b/pkg/s3/signature4/v4-signature.go
@@ -14,7 +14,15 @@
  * limitations under the License.
  */
 
-package signature
+// Package signature4 implements helper functions to validate AWS
+// Signature Version '4' authorization header.
+//
+// This package provides comprehensive helpers for following signature
+// types.
+// - Based on Authorization header.
+// - Based on Query parameters.
+// - Based on Form POST policy.
+package signature4
 
 import (
 	"bytes"
@@ -30,8 +38,8 @@ import (
 	"github.com/minio/minio/pkg/probe"
 )
 
-// Signature - local variables
-type Signature struct {
+// Sign - local variables
+type Sign struct {
 	accessKeyID            string
 	secretAccessKey        string
 	region                 string
@@ -39,6 +47,7 @@ type Signature struct {
 	extractedSignedHeaders http.Header
 }
 
+// AWS Signature Version '4' constants.
 const (
 	signV4Algorithm = "AWS4-HMAC-SHA256"
 	iso8601Format   = "20060102T150405Z"
@@ -46,7 +55,7 @@ const (
 )
 
 // New - initialize a new authorization checkes.
-func New(accessKeyID, secretAccessKey, region string) (*Signature, *probe.Error) {
+func New(accessKeyID, secretAccessKey, region string) (*Sign, *probe.Error) {
 	if !isValidAccessKey.MatchString(accessKeyID) {
 		return nil, ErrInvalidAccessKeyID("Invalid access key id.", accessKeyID).Trace(accessKeyID)
 	}
@@ -56,7 +65,7 @@ func New(accessKeyID, secretAccessKey, region string) (*Signature, *probe.Error)
 	if region == "" {
 		return nil, ErrRegionISEmpty("Region is empty.").Trace()
 	}
-	signature := &Signature{
+	signature := &Sign{
 		accessKeyID:     accessKeyID,
 		secretAccessKey: secretAccessKey,
 		region:          region,
@@ -65,7 +74,7 @@ func New(accessKeyID, secretAccessKey, region string) (*Signature, *probe.Error)
 }
 
 // SetHTTPRequestToVerify - sets the http request which needs to be verified.
-func (s *Signature) SetHTTPRequestToVerify(r *http.Request) *Signature {
+func (s *Sign) SetHTTPRequestToVerify(r *http.Request) *Sign {
 	// Do not set http request if its 'nil'.
 	if r == nil {
 		return s
@@ -75,7 +84,7 @@ func (s *Signature) SetHTTPRequestToVerify(r *http.Request) *Signature {
 }
 
 // getCanonicalHeaders generate a list of request headers with their values
-func (s Signature) getCanonicalHeaders(signedHeaders http.Header) string {
+func (s Sign) getCanonicalHeaders(signedHeaders http.Header) string {
 	var headers []string
 	vals := make(http.Header)
 	for k, vv := range signedHeaders {
@@ -107,7 +116,7 @@ func (s Signature) getCanonicalHeaders(signedHeaders http.Header) string {
 }
 
 // getSignedHeaders generate a string i.e alphabetically sorted, semicolon-separated list of lowercase request header names
-func (s Signature) getSignedHeaders(signedHeaders http.Header) string {
+func (s Sign) getSignedHeaders(signedHeaders http.Header) string {
 	var headers []string
 	for k := range signedHeaders {
 		headers = append(headers, strings.ToLower(k))
@@ -127,7 +136,7 @@ func (s Signature) getSignedHeaders(signedHeaders http.Header) string {
 //  <SignedHeaders>\n
 //  <HashedPayload>
 //
-func (s *Signature) getCanonicalRequest() string {
+func (s *Sign) getCanonicalRequest() string {
 	payload := s.httpRequest.Header.Get(http.CanonicalHeaderKey("x-amz-content-sha256"))
 	s.httpRequest.URL.RawQuery = strings.Replace(s.httpRequest.URL.Query().Encode(), "+", "%20", -1)
 	encodedPath := getURLEncodedName(s.httpRequest.URL.Path)
@@ -154,7 +163,7 @@ func (s *Signature) getCanonicalRequest() string {
 //  <SignedHeaders>\n
 //  <HashedPayload>
 //
-func (s Signature) getPresignedCanonicalRequest(presignedQuery string) string {
+func (s Sign) getPresignedCanonicalRequest(presignedQuery string) string {
 	rawQuery := strings.Replace(presignedQuery, "+", "%20", -1)
 	encodedPath := getURLEncodedName(s.httpRequest.URL.Path)
 	// Convert any space strings back to "+".
@@ -171,7 +180,7 @@ func (s Signature) getPresignedCanonicalRequest(presignedQuery string) string {
 }
 
 // getScope generate a string of a specific date, an AWS region, and a service.
-func (s Signature) getScope(t time.Time) string {
+func (s Sign) getScope(t time.Time) string {
 	scope := strings.Join([]string{
 		t.Format(yyyymmdd),
 		s.region,
@@ -182,7 +191,7 @@ func (s Signature) getScope(t time.Time) string {
 }
 
 // getStringToSign a string based on selected query values.
-func (s Signature) getStringToSign(canonicalRequest string, t time.Time) string {
+func (s Sign) getStringToSign(canonicalRequest string, t time.Time) string {
 	stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
 	stringToSign = stringToSign + s.getScope(t) + "\n"
 	canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
@@ -191,7 +200,7 @@ func (s Signature) getStringToSign(canonicalRequest string, t time.Time) string
 }
 
 // getSigningKey hmac seed to calculate final signature.
-func (s Signature) getSigningKey(t time.Time) []byte {
+func (s Sign) getSigningKey(t time.Time) []byte {
 	secret := s.secretAccessKey
 	date := sumHMAC([]byte("AWS4"+secret), []byte(t.Format(yyyymmdd)))
 	region := sumHMAC(date, []byte(s.region))
@@ -201,27 +210,27 @@ func (s Signature) getSigningKey(t time.Time) []byte {
 }
 
 // getSignature final signature in hexadecimal form.
-func (s Signature) getSignature(signingKey []byte, stringToSign string) string {
+func (s Sign) getSignature(signingKey []byte, stringToSign string) string {
 	return hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
 }
 
 // DoesPolicySignatureMatch - Verify query headers with post policy
 //     - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
 // returns true if matches, false otherwise. if error is not nil then it is always false
-func (s *Signature) DoesPolicySignatureMatch(formValues map[string]string) (bool, *probe.Error) {
+func (s *Sign) DoesPolicySignatureMatch(formValues map[string]string) (bool, *probe.Error) {
 	// Parse credential tag.
-	creds, err := parseCredential("Credential=" + formValues["X-Amz-Credential"])
+	credential, err := parseCredential("Credential=" + formValues["X-Amz-Credential"])
 	if err != nil {
 		return false, err.Trace(formValues["X-Amz-Credential"])
 	}
 
 	// Verify if the access key id matches.
-	if creds.accessKeyID != s.accessKeyID {
-		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", creds.accessKeyID).Trace(creds.accessKeyID)
+	if credential.accessKeyID != s.accessKeyID {
+		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", credential.accessKeyID).Trace(credential.accessKeyID)
 	}
 
 	// Verify if the region is valid.
-	reqRegion := creds.scope.region
+	reqRegion := credential.scope.region
 	if !isValidRegion(reqRegion, s.region) {
 		return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
 	}
@@ -245,20 +254,20 @@ func (s *Signature) DoesPolicySignatureMatch(formValues map[string]string) (bool
 // DoesPresignedSignatureMatch - Verify query headers with presigned signature
 //     - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
 // returns true if matches, false otherwise. if error is not nil then it is always false
-func (s *Signature) DoesPresignedSignatureMatch() (bool, *probe.Error) {
+func (s *Sign) DoesPresignedSignatureMatch() (bool, *probe.Error) {
 	// Parse request query string.
-	preSignV4Values, err := parsePreSignV4(s.httpRequest.URL.Query())
+	preSignValues, err := parsePreSignV4(s.httpRequest.URL.Query())
 	if err != nil {
 		return false, err.Trace(s.httpRequest.URL.String())
 	}
 
 	// Verify if the access key id matches.
-	if preSignV4Values.Creds.accessKeyID != s.accessKeyID {
-		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", preSignV4Values.Creds.accessKeyID).Trace(preSignV4Values.Creds.accessKeyID)
+	if preSignValues.Credential.accessKeyID != s.accessKeyID {
+		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", preSignValues.Credential.accessKeyID).Trace(preSignValues.Credential.accessKeyID)
 	}
 
 	// Verify if region is valid.
-	reqRegion := preSignV4Values.Creds.scope.region
+	reqRegion := preSignValues.Credential.scope.region
 	if !isValidRegion(reqRegion, s.region) {
 		return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
 	}
@@ -267,19 +276,19 @@ func (s *Signature) DoesPresignedSignatureMatch() (bool, *probe.Error) {
 	s.region = reqRegion
 
 	// Extract all the signed headers along with its values.
-	s.extractedSignedHeaders = extractSignedHeaders(preSignV4Values.SignedHeaders, s.httpRequest.Header)
+	s.extractedSignedHeaders = extractSignedHeaders(preSignValues.SignedHeaders, s.httpRequest.Header)
 
 	// Construct new query.
 	query := make(url.Values)
 	query.Set("X-Amz-Algorithm", signV4Algorithm)
 
-	if time.Now().UTC().Sub(preSignV4Values.Date) > time.Duration(preSignV4Values.Expires) {
+	if time.Now().UTC().Sub(preSignValues.Date) > time.Duration(preSignValues.Expires) {
 		return false, ErrExpiredPresignRequest("Presigned request already expired, please initiate a new request.")
 	}
 
 	// Save the date and expires.
-	t := preSignV4Values.Date
-	expireSeconds := int(time.Duration(preSignV4Values.Expires) / time.Second)
+	t := preSignValues.Date
+	expireSeconds := int(time.Duration(preSignValues.Expires) / time.Second)
 
 	// Construct the query.
 	query.Set("X-Amz-Date", t.Format(iso8601Format))
@@ -325,7 +334,7 @@ func (s *Signature) DoesPresignedSignatureMatch() (bool, *probe.Error) {
 // DoesSignatureMatch - Verify authorization header with calculated header in accordance with
 //     - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
 // returns true if matches, false otherwise. if error is not nil then it is always false
-func (s *Signature) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error) {
+func (s *Sign) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error) {
 	// Save authorization header.
 	v4Auth := s.httpRequest.Header.Get("Authorization")
 
@@ -339,12 +348,12 @@ func (s *Signature) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error
 	s.extractedSignedHeaders = extractSignedHeaders(signV4Values.SignedHeaders, s.httpRequest.Header)
 
 	// Verify if the access key id matches.
-	if signV4Values.Creds.accessKeyID != s.accessKeyID {
-		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", signV4Values.Creds.accessKeyID).Trace(signV4Values.Creds.accessKeyID)
+	if signV4Values.Credential.accessKeyID != s.accessKeyID {
+		return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", signV4Values.Credential.accessKeyID).Trace(signV4Values.Credential.accessKeyID)
 	}
 
 	// Verify if region is valid.
-	reqRegion := signV4Values.Creds.scope.region
+	reqRegion := signV4Values.Credential.scope.region
 	if !isValidRegion(reqRegion, s.region) {
 		return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
 	}
diff --git a/pkg/signature/utils.go b/pkg/s3/signature4/v4-utils.go
similarity index 84%
rename from pkg/signature/utils.go
rename to pkg/s3/signature4/v4-utils.go
index b05aea195..270c1f2a3 100644
--- a/pkg/signature/utils.go
+++ b/pkg/s3/signature4/v4-utils.go
@@ -1,4 +1,20 @@
-package signature
+/*
+ * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package signature4
 
 import (
 	"crypto/hmac"
@@ -11,12 +27,6 @@ import (
 	"github.com/minio/minio/pkg/crypto/sha256"
 )
 
-// AccessID and SecretID length in bytes
-const (
-	MinioAccessID = 20
-	MinioSecretID = 40
-)
-
 /// helpers
 
 // isValidSecretKey - validate secret key.
diff --git a/pkg/xl/bucket.go b/pkg/xl/bucket.go
index 645257e94..2e84b0aab 100644
--- a/pkg/xl/bucket.go
+++ b/pkg/xl/bucket.go
@@ -34,7 +34,7 @@ import (
 	"github.com/minio/minio/pkg/crypto/sha256"
 	"github.com/minio/minio/pkg/crypto/sha512"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 	"github.com/minio/minio/pkg/xl/block"
 )
 
@@ -236,7 +236,7 @@ func (b bucket) ReadObject(objectName string) (reader io.ReadCloser, size int64,
 }
 
 // WriteObject - write a new object into bucket
-func (b bucket) WriteObject(objectName string, objectData io.Reader, size int64, expectedMD5Sum string, metadata map[string]string, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (b bucket) WriteObject(objectName string, objectData io.Reader, size int64, expectedMD5Sum string, metadata map[string]string, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 	if objectName == "" || objectData == nil {
diff --git a/pkg/xl/interfaces.go b/pkg/xl/interfaces.go
index ad16642d7..79cc9822b 100644
--- a/pkg/xl/interfaces.go
+++ b/pkg/xl/interfaces.go
@@ -20,7 +20,7 @@ import (
 	"io"
 
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 )
 
 // Collection of XL specification interfaces
@@ -37,7 +37,7 @@ type CloudStorage interface {
 	GetBucketMetadata(bucket string) (BucketMetadata, *probe.Error)
 	SetBucketMetadata(bucket string, metadata map[string]string) *probe.Error
 	ListBuckets() ([]BucketMetadata, *probe.Error)
-	MakeBucket(bucket string, ACL string, location io.Reader, signature *signV4.Signature) *probe.Error
+	MakeBucket(bucket string, ACL string, location io.Reader, signature *signature4.Sign) *probe.Error
 
 	// Bucket operations
 	ListObjects(string, BucketResourcesMetadata) ([]ObjectMetadata, BucketResourcesMetadata, *probe.Error)
@@ -46,7 +46,7 @@ type CloudStorage interface {
 	GetObject(w io.Writer, bucket, object string, start, length int64) (int64, *probe.Error)
 	GetObjectMetadata(bucket, object string) (ObjectMetadata, *probe.Error)
 	// bucket, object, expectedMD5Sum, size, reader, metadata, signature
-	CreateObject(string, string, string, int64, io.Reader, map[string]string, *signV4.Signature) (ObjectMetadata, *probe.Error)
+	CreateObject(string, string, string, int64, io.Reader, map[string]string, *signature4.Sign) (ObjectMetadata, *probe.Error)
 
 	Multipart
 }
@@ -55,8 +55,8 @@ type CloudStorage interface {
 type Multipart interface {
 	NewMultipartUpload(bucket, key, contentType string) (string, *probe.Error)
 	AbortMultipartUpload(bucket, key, uploadID string) *probe.Error
-	CreateObjectPart(string, string, string, int, string, string, int64, io.Reader, *signV4.Signature) (string, *probe.Error)
-	CompleteMultipartUpload(bucket, key, uploadID string, data io.Reader, signature *signV4.Signature) (ObjectMetadata, *probe.Error)
+	CreateObjectPart(string, string, string, int, string, string, int64, io.Reader, *signature4.Sign) (string, *probe.Error)
+	CompleteMultipartUpload(bucket, key, uploadID string, data io.Reader, signature *signature4.Sign) (ObjectMetadata, *probe.Error)
 	ListMultipartUploads(string, BucketMultipartResourcesMetadata) (BucketMultipartResourcesMetadata, *probe.Error)
 	ListObjectParts(string, string, ObjectResourcesMetadata) (ObjectResourcesMetadata, *probe.Error)
 }
diff --git a/pkg/xl/multipart.go b/pkg/xl/multipart.go
index 7349fa925..df03567b1 100644
--- a/pkg/xl/multipart.go
+++ b/pkg/xl/multipart.go
@@ -35,7 +35,7 @@ import (
 
 	"github.com/minio/minio/pkg/crypto/sha256"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 	"github.com/minio/minio/pkg/xl/cache/data"
 )
 
@@ -109,7 +109,7 @@ func (xl API) AbortMultipartUpload(bucket, key, uploadID string) *probe.Error {
 }
 
 // CreateObjectPart - create a part in a multipart session
-func (xl API) CreateObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signV4.Signature) (string, *probe.Error) {
+func (xl API) CreateObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signature4.Sign) (string, *probe.Error) {
 	xl.lock.Lock()
 	etag, err := xl.createObjectPart(bucket, key, uploadID, partID, "", expectedMD5Sum, size, data, signature)
 	xl.lock.Unlock()
@@ -120,7 +120,7 @@ func (xl API) CreateObjectPart(bucket, key, uploadID string, partID int, content
 }
 
 // createObject - internal wrapper function called by CreateObjectPart
-func (xl API) createObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signV4.Signature) (string, *probe.Error) {
+func (xl API) createObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signature4.Sign) (string, *probe.Error) {
 	if !IsValidBucket(bucket) {
 		return "", probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
@@ -289,7 +289,7 @@ func (xl API) mergeMultipart(parts *CompleteMultipartUpload, uploadID string, fu
 }
 
 // CompleteMultipartUpload - complete a multipart upload and persist the data
-func (xl API) CompleteMultipartUpload(bucket, key, uploadID string, data io.Reader, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (xl API) CompleteMultipartUpload(bucket, key, uploadID string, data io.Reader, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	xl.lock.Lock()
 	defer xl.lock.Unlock()
 	size := int64(xl.multiPartObjects[uploadID].Stats().Bytes)
@@ -307,7 +307,7 @@ func (xl API) CompleteMultipartUpload(bucket, key, uploadID string, data io.Read
 	return objectMetadata, nil
 }
 
-func (xl API) completeMultipartUploadV2(bucket, key, uploadID string, data io.Reader, signature *signV4.Signature) (io.Reader, *probe.Error) {
+func (xl API) completeMultipartUploadV2(bucket, key, uploadID string, data io.Reader, signature *signature4.Sign) (io.Reader, *probe.Error) {
 	if !IsValidBucket(bucket) {
 		return nil, probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
diff --git a/pkg/xl/xl-v1.go b/pkg/xl/xl-v1.go
index 613684a8f..723f6d5b4 100644
--- a/pkg/xl/xl-v1.go
+++ b/pkg/xl/xl-v1.go
@@ -35,7 +35,7 @@ import (
 	"github.com/minio/minio/pkg/crypto/sha256"
 	"github.com/minio/minio/pkg/crypto/sha512"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 	"github.com/minio/minio/pkg/xl/block"
 )
 
@@ -128,7 +128,7 @@ func (xl API) listObjects(bucket, prefix, marker, delimiter string, maxkeys int)
 }
 
 // putObject - put object
-func (xl API) putObject(bucket, object, expectedMD5Sum string, reader io.Reader, size int64, metadata map[string]string, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (xl API) putObject(bucket, object, expectedMD5Sum string, reader io.Reader, size int64, metadata map[string]string, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
 		return ObjectMetadata{}, probe.NewError(InvalidArgument{})
 	}
@@ -160,7 +160,7 @@ func (xl API) putObject(bucket, object, expectedMD5Sum string, reader io.Reader,
 }
 
 // putObject - put object
-func (xl API) putObjectPart(bucket, object, expectedMD5Sum, uploadID string, partID int, reader io.Reader, size int64, metadata map[string]string, signature *signV4.Signature) (PartMetadata, *probe.Error) {
+func (xl API) putObjectPart(bucket, object, expectedMD5Sum, uploadID string, partID int, reader io.Reader, size int64, metadata map[string]string, signature *signature4.Sign) (PartMetadata, *probe.Error) {
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
 		return PartMetadata{}, probe.NewError(InvalidArgument{})
 	}
@@ -337,7 +337,7 @@ func (xl API) listObjectParts(bucket, object string, resources ObjectResourcesMe
 }
 
 // completeMultipartUpload complete an incomplete multipart upload
-func (xl API) completeMultipartUpload(bucket, object, uploadID string, data io.Reader, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (xl API) completeMultipartUpload(bucket, object, uploadID string, data io.Reader, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
 		return ObjectMetadata{}, probe.NewError(InvalidArgument{})
 	}
diff --git a/pkg/xl/xl-v2.go b/pkg/xl/xl-v2.go
index 962943b46..7d6a40ba5 100644
--- a/pkg/xl/xl-v2.go
+++ b/pkg/xl/xl-v2.go
@@ -34,7 +34,7 @@ import (
 	"github.com/minio/minio/pkg/crypto/sha256"
 	"github.com/minio/minio/pkg/probe"
 	"github.com/minio/minio/pkg/quick"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 	"github.com/minio/minio/pkg/xl/cache/data"
 	"github.com/minio/minio/pkg/xl/cache/metadata"
 )
@@ -267,7 +267,7 @@ func isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) *probe.Error {
 }
 
 // CreateObject - create an object
-func (xl API) CreateObject(bucket, key, expectedMD5Sum string, size int64, data io.Reader, metadata map[string]string, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (xl API) CreateObject(bucket, key, expectedMD5Sum string, size int64, data io.Reader, metadata map[string]string, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	xl.lock.Lock()
 	defer xl.lock.Unlock()
 
@@ -280,7 +280,7 @@ func (xl API) CreateObject(bucket, key, expectedMD5Sum string, size int64, data
 }
 
 // createObject - PUT object to cache buffer
-func (xl API) createObject(bucket, key, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signV4.Signature) (ObjectMetadata, *probe.Error) {
+func (xl API) createObject(bucket, key, contentType, expectedMD5Sum string, size int64, data io.Reader, signature *signature4.Sign) (ObjectMetadata, *probe.Error) {
 	if len(xl.config.NodeDiskMap) == 0 {
 		if size > int64(xl.config.MaxSize) {
 			generic := GenericObjectError{Bucket: bucket, Object: key}
@@ -414,7 +414,7 @@ func (xl API) createObject(bucket, key, contentType, expectedMD5Sum string, size
 }
 
 // MakeBucket - create bucket in cache
-func (xl API) MakeBucket(bucketName, acl string, location io.Reader, signature *signV4.Signature) *probe.Error {
+func (xl API) MakeBucket(bucketName, acl string, location io.Reader, signature *signature4.Sign) *probe.Error {
 	xl.lock.Lock()
 	defer xl.lock.Unlock()
 
diff --git a/routers.go b/routers.go
index 496396d36..45f7d1a6c 100644
--- a/routers.go
+++ b/routers.go
@@ -27,7 +27,7 @@ import (
 	"github.com/minio/minio-go"
 	"github.com/minio/minio/pkg/fs"
 	"github.com/minio/minio/pkg/probe"
-	signV4 "github.com/minio/minio/pkg/signature"
+	"github.com/minio/minio/pkg/s3/signature4"
 )
 
 // storageAPI container for S3 compatible API.
@@ -37,7 +37,7 @@ type storageAPI struct {
 	// Filesystem instance.
 	Filesystem fs.Filesystem
 	// Signature instance.
-	Signature *signV4.Signature
+	Signature *signature4.Sign
 	// Region instance.
 	Region string
 }
@@ -141,7 +141,7 @@ func initAPI(conf cloudServerConfig) storageAPI {
 	fs, err := fs.New(conf.Path, conf.MinFreeDisk)
 	fatalIf(err.Trace(), "Initializing filesystem failed.", nil)
 
-	sign, err := signV4.New(conf.AccessKeyID, conf.SecretAccessKey, conf.Region)
+	sign, err := signature4.New(conf.AccessKeyID, conf.SecretAccessKey, conf.Region)
 	fatalIf(err.Trace(conf.AccessKeyID, conf.SecretAccessKey, conf.Region), "Initializing signature version '4' failed.", nil)
 
 	return storageAPI{
diff --git a/signature.go b/signature.go
deleted file mode 100644
index e96a219e0..000000000
--- a/signature.go
+++ /dev/null
@@ -1,94 +0,0 @@
-/*
- * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package main
-
-import (
-	"crypto/sha256"
-	"encoding/hex"
-	"net/http"
-	"strings"
-
-	signV4 "github.com/minio/minio/pkg/signature"
-)
-
-// Verify if request has JWT.
-func isRequestJWT(r *http.Request) bool {
-	if _, ok := r.Header["Authorization"]; ok {
-		if strings.HasPrefix(r.Header.Get("Authorization"), jwtAlgorithm) {
-			return ok
-		}
-	}
-	return false
-}
-
-// Verify if request has AWS Signature Version '4'.
-func isRequestSignatureV4(r *http.Request) bool {
-	if _, ok := r.Header["Authorization"]; ok {
-		if strings.HasPrefix(r.Header.Get("Authorization"), signV4Algorithm) {
-			return ok
-		}
-	}
-	return false
-}
-
-// Verify if request has AWS Presignature Version '4'.
-func isRequestPresignedSignatureV4(r *http.Request) bool {
-	if _, ok := r.URL.Query()["X-Amz-Credential"]; ok {
-		return ok
-	}
-	return false
-}
-
-// Verify if request has AWS Post policy Signature Version '4'.
-func isRequestPostPolicySignatureV4(r *http.Request) bool {
-	if _, ok := r.Header["Content-Type"]; ok {
-		if strings.Contains(r.Header.Get("Content-Type"), "multipart/form-data") {
-			return true
-		}
-	}
-	return false
-}
-
-// Verify if request requires ACL check.
-func isRequestRequiresACLCheck(r *http.Request) bool {
-	if isRequestSignatureV4(r) || isRequestPresignedSignatureV4(r) || isRequestPostPolicySignatureV4(r) {
-		return false
-	}
-	return true
-}
-
-// Verify if request has valid AWS Signature Version '4'.
-func isSignV4ReqAuthenticated(sign *signV4.Signature, r *http.Request) bool {
-	auth := sign.SetHTTPRequestToVerify(r)
-	if isRequestSignatureV4(r) {
-		dummyPayload := sha256.Sum256([]byte(""))
-		ok, err := auth.DoesSignatureMatch(hex.EncodeToString(dummyPayload[:]))
-		if err != nil {
-			errorIf(err.Trace(), "Signature verification failed.", nil)
-			return false
-		}
-		return ok
-	} else if isRequestPresignedSignatureV4(r) {
-		ok, err := auth.DoesPresignedSignatureMatch()
-		if err != nil {
-			errorIf(err.Trace(), "Presigned signature verification failed.", nil)
-			return false
-		}
-		return ok
-	}
-	return false
-}