Endpoint Encryption

I have a number of self-decrypting archive files that contain between 5 to 2 files. When I double-click on the SDA file (.exe) and the contents are extracted, I noticed that the date modified of these files is set to the current time and date the extraction occurs.

I've tested with a standard PGP encrypted file and the same occurs when using the 'Verify and Decrypt' option, however if I double-click on a PGP file to open it, and then highlight the files and choose extract, the modified date stays as the date of the file itself

Is there a way to prevent the modified date from being altered when extracting from an SDA file at all?

I've recreated your circumstances, and you're right.  The modified date does change.  I think this is just due to the encryption process.  I cannot see a way around it unfortunately.

The basic result is the same for other ZIP files, including the default Windows ZIP files.  When you perform an 'Extract All' type of operation, the files show as modified.  I think it has something to do with how the operation is carried out.

When creating a Zip file, you are effectively combining data into a single compressed file.  When you extract a single file from the Zip, only the data from that portion of the zip file is pulled, which should result in an exact, unmodified duplicate.  When you extract all, it basically reads the entire Zip file, and rebuilds the other files iteratively.  At this point, it is effectively creating new files from a single master (zip) file.

Since the self-decrypting archive is an executable, I think it would always basically be doing an 'Extract All' type of operation, so there would not be a way to keep the modified date the same as the original.

This is a very simplified explanation based on my somewhat limited understanding of the inner workings of a Zip file.  Let me know if it makes sense to you.

That actually makes perfect sense, thank you!