base64 有的字符:

• A-Z
• a-z
• 0-9
• +
• /
• =          pad

Example:

import base64

# encode(in, out),decode(in, out), encodestring(str),decodestring(str)

def main():
    mystring = 'testing'
    before = base64.encodestring(mystring)
    print base64.decodestring(before)

if __name__ == '__main__':
    main()