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Python security - trouble with input

The danger of Python's input function - also known as giving away your secrets to your user.

If you're writing a Python program and asking your user for input, you should always use the raw_input function and never input. Why? Because what you type to input is interpretted through an expression and the result is saved into your target variable ... so not only does input assume that your user knows Python syntax, but it also opens some great little security holes.

Look at this program.

Something = "your toes"
Secret = "I have ten of them"

value = input("Please enter your age ")
print "You are",value,
print "and you have a secret about",Something


And look how easy it is to find out all the variables that are used inthe program, and their contents:

earth-wind-and-fire$ python dain
Please enter your age dir()
You are ['Secret', 'Something', '__builtins__', '__doc__', '__file__', '__name__'] and you have a secret about your toes
earth-wind-and-fire:$ python dain
Please enter your age Secret
You are I have ten of them and you have a secret about your toes
earth-wind-and-fire:$


First run ... find out what all the defined variables are called. Second run ... start reading those variables. Ouch!
(written 2006-11-30)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y102 - Python - Fundamentals
  [4324] Learning to program - variables and constants - (2014-11-22)
  [3917] BODMAS - the order a computer evaluates arithmetic expressions - (2012-11-09)
  [3886] Formatting output - why we need to, and first Python example - (2012-10-09)
  [3551] Some terms used in programming (Biased towards Python) - (2011-12-12)
  [3278] Do I need to initialise variables - programming in C, C++, Perl, PHP, Python, Ruby or Java. - (2011-05-05)
  [3181] Beware - a=a+b and a+=b are different - Python - (2011-02-23)
  [3083] Python - fresh examples from recent courses - (2010-12-11)
  [2778] Learning to program in Python 2 ... and / or in Python 3 - (2010-05-24)
  [2442] Variable storage - Perl, Tcl and Python compared - (2009-10-08)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [1878] Pascals Triangle in Python and Java - (2008-11-10)
  [1461] Python - input v raw input - (2007-12-06)
  [1448] Question on division (Java) - Also Perl, PHP, Python ... - (2007-11-28)
  [1430] Integer v float - Python - (2007-11-12)
  [748] Getting rid of variables after you have finished with them - (2006-06-06)
  [633] Copying a reference, or cloning - (2006-03-05)
  [328] Making programs easy for any user to start - (2005-05-29)


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