Hash

Description

Converts a variable-length string to a 32-byte, hexadecimal string, using the MD5 algorithm. (It is not possible to convert the hash result back to the source string.)

Return value

32-byte, hexadecimal string

Syntax

Hash(string)

Parameters

Parameter Description

string
A string or a variable that contains one.

Parameter	Description
string	A string or a variable that contains one.

Usage

The result is useful for comparison and validation. For example, a developer can store the hash of a password in a database without exposing the password. The developer can check the validity of the password with the following code:

<cfif hash(form.password) is not myQuery.passwordHash>

  <cflocation url = "unauthenticated.cfm">
</cfif>

Example

<!--- How to use Hash for password validation. This assumes that UserID 
value is passed to this page with a URL parameter. --->
<h3>Hash Example</h3>

<cfquery name = "CheckPerson" datasource = "UserData">
  SELECT PasswordHash
  FROM SecureData
  WHERE UserID = <cfqueryparam value = "#UserID#"
    cfsqltype = "CF_SQL_CHARVAR"> 
</cfquery>

<cfif Hash(form.password) is not checkperson.passwordHash>
  <cflocation url = "unauthenticated.cfm">
<cfelse>
  ...
</cfif>