Improve security and simplify code

- Make variable name more semantic
- Reduce cyclomatic complexities for the formula calculate function
- Support specified unzip size limit on open file options, avoid zip bombs vulnerability attack
- Typo fix for documentation and error message

1 files changed, 6 insertions, 4 deletions

diff --git a/crypt.go b/crypt.go
index a0096c9..24ac7ec 100644
--- a/crypt.go
+++ b/crypt.go
@@ -3,9 +3,11 @@
 // the LICENSE file.
 //
 // Package excelize providing a set of functions that allow you to write to
-// and read from XLSX files. Support reads and writes XLSX file generated by
-// Microsoft Excel™ 2007 and later. Support save file without losing original
-// charts of XLSX. This library needs Go version 1.15 or later.
+// and read from XLSX / XLSM / XLTM files. Supports reading and writing
+// spreadsheet documents generated by Microsoft Excel™ 2007 and later. Supports
+// complex components by high compatibility, and provided streaming API for
+// generating or reading data from a worksheet with huge amounts of data. This
+// library needs Go version 1.15 or later.
 
 package excelize
 
@@ -15,6 +17,7 @@ import (
 	"crypto/cipher"
 	"crypto/hmac"
 	"crypto/md5"
+	"crypto/rand"
 	"crypto/sha1"
 	"crypto/sha256"
 	"crypto/sha512"
@@ -22,7 +25,6 @@ import (
 	"encoding/binary"
 	"encoding/xml"
 	"hash"
-	"math/rand"
 	"reflect"
 	"strings"