{"id":3551,"date":"2013-08-02T19:32:54","date_gmt":"2013-08-02T10:32:54","guid":{"rendered":"http:\/\/fujiitoshiki.com\/improvesociety\/?p=3551"},"modified":"2017-04-27T15:21:53","modified_gmt":"2017-04-27T06:21:53","slug":"how-to-apply-constraints-to-password-with-regular-expression-which-requires-single-byte-alphanumeric-characters-and-symbols","status":"publish","type":"post","link":"https:\/\/www.fujiitoshiki.com\/improvesociety\/?p=3551","title":{"rendered":"How to validate password with regular expression which requires single-byte alphanumeric characters and symbols?"},"content":{"rendered":"

It’s needed to enter password which requires a character, a number and a symbol at least, respectively. I’d like to describe how to validate password with VBScript®. It’s assumed that the length of password is 8 or greater. <\/p>\n

\"EnterPassword\"<\/a><\/p>\n

In 23 line, the constraint is shown. In 22 line with comment, it’s shown that constrains password to require both a single-byte character and number at least and 8 or greater character length. <\/p>\n

Option Explicit\r\n\r\nPrivate Sub CommandButton1_Click()\r\n    With TextBox1\r\n        If Not CheckPassword(.Text) Then\r\n            .SetFocus\r\n            .SelStart = 0\r\n            .SelLength = Len(.Text)\r\n            Exit Sub\r\n        Else\r\n            \r\n        End If\r\n    End With\r\n    Unload Me\r\nEnd Sub\r\n\r\nFunction CheckPassword(InputString As String) As Boolean\r\n    Dim myReg   As Object\r\n    CheckPassword = False\r\n    Set myReg = CreateObject(\"VBScript.RegExp\")\r\n    With myReg\r\n       '.Pattern = \"(?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]{8,})$\"\r\n        .Pattern = \"(?!^[0-9]*$)(?!^[a-zA-Z]*$)(?!^[!-\/:-@[-`{-~]*$)(?!^[a-zA-Z0-9]*$)(?!^[!-@[-`{-~]*$)(?!^[!-\/:-~]*$)^([!-~]{8,})$\"\r\n        .IgnoreCase = False\r\n        .Global = True\r\n    End With\r\n    If myReg.Test(InputString) Then\r\n        CheckPassword = True\r\n    End If\r\n    Set myReg = Nothing\r\nEnd Function\r\n\r\nPrivate Sub UserForm_Initialize()\r\n    With TextBox1\r\n        .IMEMode = fmIMEModeDisable\r\n        .PasswordChar = \"*\"\r\n    End With\r\nEnd Sub\r\n<\/pre>\n
You might need description here. The pattern (?!pattern<\/em>) means such negative lookahead as EXCEPT operator effects in SQL. To seek area three circles overlap, it’s needed to remove areas around. After filtering out not required patterns with negative lookahead, it validates length of the password. The number of required pattern, which verifies n types of letter, is 2n<\/sup> – 2. <\/p>\n\n\n\n\n\n\n\n\n\n
Not Needed<\/span><\/td>\nNegative Lookahead Pattern<\/span><\/td>\n<\/tr>\n
Number<\/span><\/td>\n(?!^[0-9]*$)<\/span><\/td>\n<\/tr>\n
Character<\/span><\/td>\n(?!^[a-zA-Z]*$)<\/span><\/td>\n<\/tr>\n
Symbol<\/span><\/td>\n(?!^[!-\/:-@[-`{-~]*$)<\/span><\/td>\n<\/tr>\n
Character and number<\/span><\/td>\n(?!^[a-zA-Z0-9]*$)<\/span><\/td>\n<\/tr>\n
Number and symbol<\/span><\/td>\n(?!^[!-@[-`{-~]*$)<\/span><\/td>\n<\/tr>\n
Character and symbol<\/span><\/td>\n(?!^[!-\/:-~]*$)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\"PasswordValidation\"<\/a><\/p>\n
References:
\nRegular Expression Language – Quick Reference<\/a>
\nHow To: Use Regular Expressions to Constrain Input in ASP.NET<\/a>
\nASCII character code list (0-127)<\/a>
\nUserform of Excel VBA as user interface<\/a><\/p>\n