How to make BOA security

Hi all.

I 'm developing cgi program based on BOA. When users type in user-name and password in FORM, and submit with POST, Others can capture the information because in web browsers data isn't encrypted.

Maybe MD5 can work in BOA, but it can't solve the problem. People get data during translation, not on the web server end.

Above is my think, I don't know whether it is right!!

Please tell me, How to protect login name and password. What should I do?

Thank you.