How do I use Encryption with my Password Control

[Ryno Bower]

Hello.

How would I apply SHA2 Cryptographic Hash Algorithm for VBA and VBScript to a password control on a form?

Thanks

[Rabbit]

You run the input through the function before storing it in the table.

[NeoPa]

And when a password is entered on your form as credentials, you run it through the encryption algorithm and compare the result with what was stored.

[Ryno Bower]

Could this be in the AfterUpdate method??

[NeoPa]

It could be, but for something like this you typically want to allow the operator to make changes before confirming the credentials to use, so you put the code behind a Command Button.

[Ryno Bower]

Ok so if I create a new operator, I should have the password field. Enter the desired password and on the click of the command button to create the operator I should enter the code!

The code: can it be saved as a module and then be called back on the click of the button?
How do I call it then?
Hope my question is clear?

[NeoPa]

Ryno Bower:
Ok so if I create a new operator, I should have the password field. Enter the desired password and on the click of the command button to create the operator I should enter the code!

You call the code passing your actual password, then save the returned value in your table.

Ryno Bower:
The code: can it be saved as a module and then be called back on the click of the button?

Yes. It's saved in a module. There's no other way I know of using it.

Ryno Bower:
How do I call it then?

You say something like :

SavedPassword = SHA(Me.txtPassword)

[Rabbit]

A quick note about the return value of the function, it returns a 32 byte array. You will have to convert that to a string before storing it in a field. You can either store the hash as its byte for byte string equivalent (nonprintable characters and all) or you can store it as a more human friendly hexadecimal string. The former uses less space but can't be read by a human and the latter is the opposite.

[Ryno Bower]

I need help!
I have created the code (module) and called it PasswordCode.

I have a form and on the form is fields UserName linked to the underlying table.
Also I have an unbound text field called txtPassword with the password input mask.
Also I have the password field linked to the underlying table callled SavedPassword.

Also I have a button. I have the code as you suggested when I click the button.
SavedPassword = SHA(meMtxtPassword)

When I click the button it should insert the encrypted password into the SavedPassword field right?

I get an error message that the value you entered isn't valid for this field.

Is my code right?

[Rabbit]

Refer to my previous post.

[Ryno Bower]

Would it look something like this?

Dim spw As String
spw = me.SavedPassword
 
Spw = SHA(me.txtPassword)

I still get error 94: invalid use of null

Please help

[Rabbit]

You didn't pick one of the two options I laid out in post #8. But whichever option you decide to choose, that's not what it would look like. At a minimum, you would need a loop to iterate through the array that's returned.

[Ryno Bower]

Could you give me a sample code?
This is confusing to me.
I thought that I made the field a string as you said earlier!

Thanks

[Rabbit]

I don't see anything in your code that changes the 32 byte integer array into a string.

Here's an example of a loop.

Dim i, j
j = 0
For i = 0 To 31
   j = j + 1
Next

It adds 1 to j 32 times.

[Ryno Bower]

Ok thanks.

But I don't think ill know to interpret that into changing the field toa string!
I guess I am just to dumb to understand it!

[Rabbit]

What you should do is find a good VBA tutorial and have a go at that before returning to this.

[NeoPa]

Ryno Bower:
I guess I am just to dumb to understand it!

We all start somewhere Ryno.

What is certainly less than clever is to ask for help with the very basics of code without first putting some effort into getting to speed up to at least that level. You wouldn't ask a heart surgeon to put a plaster on for you. You would be expected to manage that all by yourself. It's basic, and easily achievable, with a minimum of effort and without the need to ask for assistance.

[Ryno Bower]

Any suggestions where I could find tutorials on VBA?

[Ryno Bower]

By the way! If I get this right, will the password show as ******?

[NeoPa]

Ryno Bower:
Any suggestions where I could find tutorials on VBA?

Try theses :

1. Microsoft Access Tutorials (Strive4Peace).
2. Microsoft Access Tutorials
3. Microsoft Office Tutorials.
4. VBA Tutorial (Excel).

They may not all suit you but I expect you'll find some of them very helpful.

Remember though, you may need a better understanding of the fundamentals of coding too. These can help with that to a limited extent, and they're what I have as I work in this area. Try some of them and see if this thread makes more sense to you. If not, look out for something that deals with the fundamentals of programming, rather than these which are are MS Office-specific.

Ryno Bower:
By the way! If I get this right, will the password show as ******?

On your form it will show that way as it is only ever shown when the operator types it in. You should never display a saved password, even though it's in an encrypted form.