programming-for-dummies

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Cracking Encryption
Think of a dictionary attack as a smarter and faster version of a brute force
attack. The odds of someone choosing a password, like S&$J#, is much less
than someone choosing a password of SONYA, which is why dictionary
attacks are so often successful.
Plaintext and ciphertext attacks
The easiest way to defeat any form of encryption is to steal the original
plaintext message. Although this lets you read a single message, it doesn’t
help you read any additional messages encrypted with the same password.
However, after you have the plaintext version of a message along with the
encrypted version of that same message, you can deduce the password used
to encrypt that message.
Comparing the plaintext version of a message with its encrypted version is a
plaintext attack. Because it’s rarely possible to retrieve the plaintext of an
entire message, a more common code-breaking technique is to examine the
ciphertext for patterns with frequency analysis.
The idea behind frequency analysis is that certain letters (such as e) or
words (such as and) are more likely to appear in a message. A poor encryption
algorithm encrypts the letter e and the word and with identical characters
in different parts of the encrypted message. From this simple clue, it’s
possible to gradually deduce the encrypted symbols that represent the
second-most-frequently used letters and words.
Although no form of encryption is unbreakable, the goal of every encryption
algorithm is to resist all known forms of attack so as to make cracking the
encryption unfeasible due to the lack of time or resources. As computers get
faster and more powerful, today’s encryption algorithms will only get weaker
and easier to crack. By the time that occurs, mathematicians and computer
scientists will have created newer and better encryption algorithms until
those age and become easily broken all over again.