Password Cracking and a Brief Guide to Encryption Technology

Various methods are used to break encryption, or to crack passwords, most of which use algorithms with different implementations.

Encryption Strength Comparisons
Type	Implementation	Security Level*	Speed to Decrypt
DES	40 – 56bit Shared Secret	Low	Fast
Idea	128bit Shared Secret	Military Grade	Fast
MD5	128 bit Message Digest	High	Fast
SHA	160 bit Message Digest	High	Slow
Blowfish	256 to 448 bit Shared Secret	Military Grade	Medium
RSA	2048 bit Public Key	Military Grade	Very Slow

Definitions of Implementation levels:

Shared Secret, (Symmetric):

A classic type of encryption. The instigator or the encryption uses a password which is used to encrypt the message, then communicates that password to the recipient, who then uses the same password to decrypt the message.

IDEA – A Swiss algorithm which is very strong and is the backbone of PGP. It is very fast and is used up to 128 bit. It is a tested algorithm, is high security, and very fast.

Blowfish – This is a 64 bit block cipher and has current implementations to 448 bit keys. Much stronger that DES, but slower.

RC4 - A fast stream cipher considered ‘secure’ within 128 bit variants. It is the crypto behind SSL.

DES – This is the industry standard. Fast but not very secure. It is currently the most widely used encryption algorithm in the world.

Public Key, (Asymmetric)

This is a two part key. One part is used to encrypt the file, the other key is used to decrypt. Mathematically, it is very difficult to calculate one key if only one is available.

RSA – Public key encryption relies on the fact that numbers get geometrically larger, the longer it takes to factor them will increase exponentially. PGP uses the Public Key Scheme.

One way Digests

These are ‘Hashing’ algorithms that translate an indefinite length of data into a fixed length unique number or Hash. They are useful in sealing a message digitally as it is deemed impossible that two messages have the same Hash. Hashing is also used to check the integrity of a file or files.

MD5 – 128 bit message digest used for checking that files have not been altered.

SHA – 160 bit message digest used for checking that files have not been altered.

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