switch to maintained lib (#16532)

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Andrew Thornton <art27@cantab.net>

vendor/github.com/golang-jwt/jwt/none.go

@@ -0,0 +1,52 @@
+package jwt
+
+// Implements the none signing method.  This is required by the spec
+// but you probably should never use it.
+var SigningMethodNone *signingMethodNone
+
+const UnsafeAllowNoneSignatureType unsafeNoneMagicConstant = "none signing method allowed"
+
+var NoneSignatureTypeDisallowedError error
+
+type signingMethodNone struct{}
+type unsafeNoneMagicConstant string
+
+func init() {
+	SigningMethodNone = &signingMethodNone{}
+	NoneSignatureTypeDisallowedError = NewValidationError("'none' signature type is not allowed", ValidationErrorSignatureInvalid)
+
+	RegisterSigningMethod(SigningMethodNone.Alg(), func() SigningMethod {
+		return SigningMethodNone
+	})
+}
+
+func (m *signingMethodNone) Alg() string {
+	return "none"
+}
+
+// Only allow 'none' alg type if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Verify(signingString, signature string, key interface{}) (err error) {
+	// Key must be UnsafeAllowNoneSignatureType to prevent accidentally
+	// accepting 'none' signing method
+	if _, ok := key.(unsafeNoneMagicConstant); !ok {
+		return NoneSignatureTypeDisallowedError
+	}
+	// If signing method is none, signature must be an empty string
+	if signature != "" {
+		return NewValidationError(
+			"'none' signing method with non-empty signature",
+			ValidationErrorSignatureInvalid,
+		)
+	}
+
+	// Accept 'none' signing method.
+	return nil
+}
+
+// Only allow 'none' signing if UnsafeAllowNoneSignatureType is specified as the key
+func (m *signingMethodNone) Sign(signingString string, key interface{}) (string, error) {
+	if _, ok := key.(unsafeNoneMagicConstant); ok {
+		return "", nil
+	}
+	return "", NoneSignatureTypeDisallowedError
+}