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Is there a way to determine the date of encryption or the GPG version of a GPG-encrypted file (with symmetric encryption)?

I lost the password but some rough information about when the file was encrypted would help me. (The oldest could be 5-7 years ago, newest a few months. The file modification time is also lost.)

For example, if I remember right, it could be that old versions of GPG did not have integrity checking. Can I figure this out?

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If the file is ASCII armored, you may find the header at the top.

Version: GnuPG v1.4.11 (GNU/Linux)


If it isn't then you can try to review the specification, but it's complicated and after several minutes of reading I don't have a clear answer either. See

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Thanks, and according to old package descriptions, gpg 1.4.6, the version I likely had used, if the file is old, is compatible with RFC2440. But I'm still deciding if it's too much effort. (Though, generally also an interesting security question, I think) – noozoph Dec 4 '12 at 22:28

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