Let's say you used the rabbitmqctl encode command to create an encrypted value. In this example, the string "foo" is encoded, using 'bar' as the passphrase for the encoded string.

rabbitmqctl encode foo bar

Something like this should be returned.

Encrypting value ...
{encrypted,<<"T/pCGSrOlDkpnBvUA6mOPe2aTj8UMDZKtB9FIgm0r6ql8QgroXQkaEnejuRNrKms">>}

The rabbitmqctl decode command can be used to decode an encrytped string.

rabbitmqctl decode '<<"T/pCGSrOlDkpnBvUA6mOPe2aTj8UMDZKtB9FIgm0r6ql8QgroXQkaEnejuRNrKms">>' bar

Which should return the following.

Decrypting value ...
foo