Iambestone

Hello software developers,

Please check your code to ensure you're not making one of the following mistakes related to cryptography.

I. General Mistakes

Writing your own home-grown cryptography primitives (For example: Mifare Classic)
- Exception: For the sake of learning, but don't deploy it in production.
Using a fast hash function (e.g. MD5, SHA256) for storing passwords. Use bcrypt instead.
Not using a cryptographically secure random number generator

	/*
	* Exercise 3-3. Write a function expand(s1,s2) that expands shorthand
	* notations like a-z in the string s1 into the equivalent complete list
	* abc...xyz in s2. Allow for letters of either case and digits, and be
	* prepared to handle cases like a-b-c and a-z0-9 and -a-z. Arrange that
	* a leading or trailing - is taken literally.
	*/

	#include <stdio.h>