Hash, Cryptograpy [DRAFT]
Created at 2016-09-06T16:10:46.000Z

Secure Password


  • user have hashed password
  • user don't have hashed password

Common Attacks

  • rainbow table
  • brute force

Common Technique

  • salting (to avoid rainbow table)
  • key stretching (to avoid brute force)


  • Bcrypt password hash encryption

Hash function usage and characteristics

- https://en.wikipedia.org/wiki/Cryptographic_hash_function

Example from Unix System

$ sudo passwd hiogawa
Enter new UNIX password: a1b2c3d4
Retype new UNIX password: a1b2c3d4
passwd: password updated successfully
$ sudo cat /etc/shadow | grep hiogawa
# 6 <= SHA-512
# oifbdQNc <= salt (8 characters)
# U5U3v... <= encrypted hash (86 characters)
$ openssl