gistfile1.txt

/tmp/keyfile - this is your key file. it could be anything, random text. an image. whatever you want

db_dump.sql.gz - this is your gzipped mysql dump
db_dump.sql.gz.enc - this is the output from the encryption, encrypted version if your gzipped DB dump, encrypted with your keyfile

TO ENCRYPT
openssl enc -aes-192-cbc -pass file:/tmp/keyfile -in db_dump.sql.gz -out db_dump.sql.gz.enc

TO DECRYPT
openssl enc -d -aes-192-cbc -pass file:/tmp/keyfile -in db_dump.sql.gz.enc -out db_dump.sql.gz