As long as it is not the original key, the cipher text
image can not be decrypted, even if there is a difference of one fifth.
For encryption the k value is XORed with the next byte of plain text and for decryption k value is XORed with the next byte of cipher text
This vector is XORed for the first iteration to produce the cipher text
from the original plain text.
With traditional encryption, when a database or application needs to store sensitive data such as credit card or national insurance numbers, those values are encrypted and then the cipher text
is returned to the original location.
If the stream of characters that constitute the key is truly random, then the stream of characters that constitute the cipher text
will be truly random.
Finally, Bill receives the message sent by Alice, and decrypts the message by testing the biometric keys in his database against the received cipher text
The master keys are used to encrypt all operational keys that should be stored in cipher text
in separated databases.
The fastest DES chips are designed to encrypt data with one key and not to test many keys against the same block of cipher text