programming-for-dummies

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The Basics of Encryption
After you have a valid encryption algorithm that’s been implemented properly
in a particular programming language, the final step to creating a secure
encryption algorithm is the key length used to scramble the data.
In a simple substitution cipher, the key length could be considered as the
value 1 because it offers only one way of replacing letters with another letter,
such as shifting each letter by a fixed position in the alphabet. To encrypt a
1,000-character message, a one-time pad would need 1,000 different random
numbers for shifting each letter in the message, so the key length could be
considered as 1,000.
The key length is crucial because the details of an encryption algorithm are
often published for anyone to examine. As a result, the security of most
encryption algorithms rests solely on the key length used for the password.
You don’t need to create a long password of 1,000 or more characters; the
encryption algorithm needs to use more bits of data to store any password
whether the password consists of 1 character or 100.
The length of the password simply makes it harder for other people to
guess. A 1-letter password means someone needs only 26 guesses. A 100-
letter password forces someone to try all possible combinations of letters,
making guessing much more difficult. The key length simply defines the
amount of space used to store the password but doesn’t specify the physical
length of the password.
As a simple analogy, think of encryption key lengths like the physical key to
your front door. A physical key consists of rods that drop down to prevent a
doorknob from turning. The more rods used, the harder it is to pick the lock.
The fewer rods used, the easier it is to pick the lock.
In the same way, encryption keys are used to hold passwords. The shorter
the key length (measured in bits), the fewer possibilities exist and the weaker
the encryption, making it more vulnerable to being broken. The longer the
encryption key length, the less likely the encryption will break.
No encryption is considered unbreakable, but the goal of every encryption
algorithm is to make unscrambling data so difficult that the time needed to
read the encrypted message takes too long. Typically an encrypted message
might take the world’s fastest computer a million years to break, which effectively
makes the encryption “unbreakable.”
At one time, a 56-bit key was considered unbreakable, but with today’s
computers, the smallest secure key length is 128-bits, although many
people prefer using 256-bit or 512-bit keys for added security.