We have a homework assignment to encrypt the famous Tux.ppm using AES with ECB and CBC mode. We have to show and outline how insecure the ECB mode is...

So is there any way to ignore this warning?

*** WARNING : deprecated key derivation used.
Using -iter or -pbkdf2 would be better.

1 Answer 1


To ignore it, just ignore it the way you ignore anything, by not looking at it or paying attention to it. I will consider that you want to suppress it, so it isn't there to be ignored.

  1. On Unix and Windows (which is most of the places OpenSSL is run, though not all) use 2>/dev/null or 2>NUL: respectively to discard all error messages.

  2. As it says, use -pbkdf2, or -iter which implies it, to do a better password-based derivation.

  3. Use an explicit key and IV (for CBC) with -K -iv to avoid any password-based derivation.

  4. Use a version of OpenSSL lower than 1.1.1; although 1.1.0 is off upstream support and 1.0.2 will be very soon, they are still supported to some extent (at least provided) by many packagers and distros.

  • "You ignore the warning by ignoring it" - Made me chuckle
    – user163495
    Nov 28, 2019 at 6:44
  • This was helpful: askubuntu.com/a/1126882/48214
    – Ryan
    Mar 7 at 21:37

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