Storing the current date to the registry in binary format with Inno Setup

Question

Is it possible using Inno Setup to write the current date to a registry key as binary data? (if it is a string then that makes it very easy for someone to alter)

In my MFC C++ projects I serialize a DATE variable using WriteProfileBinary.

Eventually I need to be able to read this value into a DateTime variable using .NET C#. I would be using the common program data key to store the value and only if doesn't exist.

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The [Registry] caters for binary data:

If binary is specified, Setup will create a binary (REG_BINARY) value ... If the data type is binary, this is a sequence of hexadecimal bytes in the form: "00 ff 12 34".

How to we take the timestamp and turn it into the required format?

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I see this question (Writing binary data to registry using Inno Setup Pascal Scripting) which is useful and also in the Inno Setup forum where they responded to me:

It's possible, but you'll have to use some [Code] and the RegWriteBinaryValue function.

But it is still not clear to me:

1. How to write the current timestamp to the registry using this function?
2. How to write it in a binary format such that .NET C# will be able to read it as a DateTime object?

Answer 1

To write the current date to registry as a binary value, you can do something like this:

var
  DateStr: string;
begin
  DateStr := GetDateTimeString('yyyy/mm/dd', '-', ':');
  RegWriteBinaryValue(
    HKEY_AUTO, 'Software\My Company\My Program', 'InstallDate', DateStr);
end;

It will result in:

C:\>reg query "HKCU\Software\My Company\My Program"

HKEY_CURRENT_USER\Software\My Company\My Program
    InstallDate    REG_BINARY    323032312D31302D3039  

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You can do even more obfuscation if you like. No matter what you do, user will be able to modify the value with more or less effort.