Hash

Description

Converts a variable-length string to a 32-byte, hexadecimal string, using the MD5 algorithm. The algorithm is a one-way hash-there is no conversion from the hash result back to the source string.

Syntax

Hash(string)

Parameters

Parameter

Description

string
A string

Parameter	Description
string	A string

Usage

The result of the Hash function can be used 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

<!--------------------------------------------------------------------
This code shows how to use Hash for password validation. This 
example assumes that the UserID value is passed to this page 
with a URL parameter.
---------------------------------------------------------------------->
<html>
<head>
<title>Hash Example</title>
</head>

<body bgcolor = silver>
<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>
...