Encrypt a date to use in demo version

  • Thread starter Thread starter Christie
  • Start date Start date
C

Christie

My app creates a rigistry entry of the date when it is installed, which
is then used to determine when the demo expires...It is working fine
but I would like to encrypt the date somehow...is there a relative easy
way to do this, as different machines will have different date
formats??

I am using Visual Studio 2005(VB.Net)
 
Christie said:
My app creates a rigistry entry of the date when it is installed, which
is then used to determine when the demo expires...It is working fine
but I would like to encrypt the date somehow...is there a relative easy
way to do this, as different machines will have different date
formats??

I am using Visual Studio 2005(VB.Net)
Click to expand...

Check out the System.Security.Cryptography namespace.
 
Christie said:
My app creates a rigistry entry of the date when it is installed, which
is then used to determine when the demo expires...It is working fine
but I would like to encrypt the date somehow...is there a relative easy
way to do this, as different machines will have different date
formats??

I am using Visual Studio 2005(VB.Net)
Click to expand...

Hi Christie,

Dim s1 As String = Now().ToBinary.ToString ' convert date to string
Dim d1 As Date = Date.FromBinary(Val(s1)) ' convert string back to
date

The string contains a Long numeric representation of the date/time,
which always works regardless of your regional settings.

Then it's just a matter of encrypting/decrypting the string. You could
use the Cryptography namespace as suggested; it's a bit daunting to
learn, but worth it. There's also any number of all-VB encryption
techniques you could Google up, or you could even whip up your own.
Just depends on how strong you prefer your encryption.
 
Christie said:
My app creates a rigistry entry of the date when it is installed, which
is then used to determine when the demo expires...It is working fine
but I would like to encrypt the date somehow...is there a relative easy
way to do this, as different machines will have different date
formats??

I am using Visual Studio 2005(VB.Net)
Click to expand...

Hi Christie,

Dim s1 As String = Now().ToBinary.ToString ' convert current date
to string
Dim d1 As Date = Date.FromBinary(Val(s1)) ' convert string back to
date

The string contains a numeric Long representation of the date/time,
which works regardless of the regional settings.

Then it's just a matter of encrypting/decrypting the string. You could
use the Cryptography namespace as suggested; it's a bit daunting to
learn but worth it. Or, you could Google up source code for any number
of all-VB encryption functions. Or, whip up your own. Just depends on
how strong you want your encryption.
 
Do a quick search in this news group for "Database Connectivity"
Towards the end "Izzy" posts the source code for a 128 bit encryption
scheme. I haven't tried it but you should definately check it out.

Thanks,

Seth Rowe
 
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