I use sometimes Google Drive for sharing large files. Google Drive is fast and user friendly.

I don't wish that Google sees the content of my files and try to encrypt the filename and content. My question is it really secure (Google sees only data trash) or should I optimise my command? I generate a 30-50 character password. I need to use 7zip, because I share files for non-tech-savy users.

7z a test.7z /tmp -p -mhe=on

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=utf8,Utf16=on,HugeFiles=on,64 bits,4 CPUs x64)

Scanning the drive:

WARNING: Permission denied

6 folders, 6 files, 111 bytes (1 KiB)

Creating archive: test.7z

Items to compress: 12

Enter password (will not be echoed):
Verify password (will not be echoed) :

Files read from disk: 1
Archive size: 534 bytes (1 KiB)

Scan WARNINGS for files and folders:

/tmp/cvcd/ : Permission denied

Quote from Reasons not to use Google by the pioneer Richard Stallman.

Google shut off Alexa O'Brien's Google Drive account, denying her access to it, because her reporting on Chelsea Manning's trial included copies of al-Qa'ida propaganda that was presented as evidence.

  • 1
    Using 62 alphanumeric characters (a-z, A-Z, and 0-9), you only need 22 random characters to achieve at least 128-bit security. Using 30 to 50 characters is quite overkill.
    – forest
    Commented Jul 16, 2018 at 23:43

1 Answer 1


It is reasonably secure. If google's censorship is automatic (as I suspect) it doesn't really matter either, as long as google doesn't automatically break the encryption. For 7z, they don't.

The encryption in 7z is good, and I have not heard of any practical attacks. If all you need to achieve is hiding it from automated scanning, it doesn't really matter.

If you're up against an adversary which knows the clear text you may be sharing, you should look into padding it, to hide the size.

  • 2
    For instance add a new file. Or add a unrelated image in a word file. Or add a page with a image in a PDF. In short: change the size of the message, so that your adversary can not compare it to what they know.
    – vidarlo
    Commented Jul 16, 2018 at 7:11

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