Passwords can be easily cracked or discovered if they are common words in a dictionary or less than length 7! For example, this site https://howsecureismypassword.net shows how fast passwords can be cracked.
There are two methods of password cracking:
? ? ? 26 x 26 x 26 = 263 possibilities (17,576!) For an n character password, there are 26n possibilities.
As the length and complexity of the password increases, the cracking time will exponentially increase so that a 10 character password may take 100s of years to crack on our current machines:
Most passwords are stolen by password phishing where emails trick people into typing in their passwords into fake sites, instead of using cracking.
Cracking Tools should only be used on your own files or computer or in controlled situations such as this capture the flag contest. The Recover Pdf (download here) cracking tool shows both dictionary and brute-force cracking of password locked pdf files. To use PDF Recover: