mcrypt and encrypted field length

First, can anyone point me to a good "mcrypt" primer or tutorial? Second, how can I determine what type and length I should make a database field that will hold encrypted data? Is there some table somewhere which tells how long a resulting encrypted field will be based on the encryption type and/or length of the plaintext field? Example: If I have a 20 character field and want to use Triple DES to encrypt it, can I find out how long the resulting field will be - what is the longest it will be? Will the resulting encrypted field always be the same length? Should I make the data type some variation of "text" or "varchar"? TIA. -- Hardy Merrill Mission Critical Linux, Inc. http://www.missioncriticallinux.com