cron fails to execute gpg encryption commands

Issue

• User crontab is configured to encrypt a file by running the following gnupg command, but the output file is never generated.

  gpg --passphrase-fd 3 --sign --encrypt -r Bob -o /tmp/output.gpg /home/alice/inputfile 3</home/alice/pw.txt
  

• Trying to use a gpg command in a cron job that decrypts some files with --passphrase but decryption is failing