Stop accepting legacy SHA1 signed cookies

CHANGELOG.md

@@ -4,12 +4,16 @@
 
 ## Important Notes
 
+- [#575](https://github.com/oauth2-proxy/oauth2-proxy/pull/575) Sessions from v5.1.1 or earlier will no longer validate since they were not signed with SHA1.
+  - Sessions from v6.0.0 or later had a graceful conversion to SHA256 that resulted in no reauthentication
+  - Upgrading from v5.1.1 or earlier will result in a reauthentication
 - [#616](https://github.com/oauth2-proxy/oauth2-proxy/pull/616) Ensure you have configured oauth2-proxy to use the `groups` scope. The user may be logged out initially as they may not currently have the `groups` claim however after going back through login process wil be authenticated.
 
 ## Breaking Changes
 
 ## Changes since v6.1.1
 
+- [#575](https://github.com/oauth2-proxy/oauth2-proxy/pull/575) Stop accepting legacy SHA1 signed cookies (@NickMeves)
 - [#764](https://github.com/oauth2-proxy/oauth2-proxy/pull/764) Document bcrypt encryption for htpasswd (and hide SHA) (@lentzi90)
 - [#616](https://github.com/oauth2-proxy/oauth2-proxy/pull/616) Add support to ensure user belongs in required groups when using the OIDC provider (@stefansedich)
 

pkg/encryption/utils.go

@@ -2,8 +2,6 @@ package encryption
 
 import (
 	"crypto/hmac"
-	// TODO (@NickMeves): Remove SHA1 signed cookie support in V7
-	"crypto/sha1" // #nosec G505
 	"crypto/sha256"
 	"encoding/base64"
 	"fmt"
@@ -95,16 +93,7 @@ func checkSignature(signature string, args ...string) bool {
 	if err != nil {
 		return false
 	}
-	if checkHmac(signature, checkSig) {
-		return true
-	}
-
-	// TODO (@NickMeves): Remove SHA1 signed cookie support in V7
-	legacySig, err := cookieSignature(sha1.New, args...)
-	if err != nil {
-		return false
-	}
-	return checkHmac(signature, legacySig)
+	return checkHmac(signature, checkSig)
 }
 
 func checkHmac(input, expected string) bool {

pkg/encryption/utils_test.go

@@ -94,8 +94,8 @@ func TestSignAndValidate(t *testing.T) {
 	assert.NoError(t, err)
 
 	assert.True(t, checkSignature(sha256sig, seed, key, value, epoch))
-	// This should be switched to False after fully deprecating SHA1
-	assert.True(t, checkSignature(sha1sig, seed, key, value, epoch))
+	// We don't validate legacy SHA1 signatures anymore
+	assert.False(t, checkSignature(sha1sig, seed, key, value, epoch))
 
 	assert.False(t, checkSignature(sha256sig, seed, key, "tampered", epoch))
 	assert.False(t, checkSignature(sha1sig, seed, key, "tampered", epoch))