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Running key ciphers often use a passage from a commonly available book as the encryption key.
The term "cryptosystem" is an abbreviation for "cryptographic system," and it refers to a computer system that employs cryptography, a method of safeguarding information and communications by employing codes that only those authorized to read and understand the information may do so.
A cryptosystem includes methods for creating keys, encrypting data, and decrypting it. A cryptographic key is a sequence of bits used by a cryptographic algorithm to transform plain text to ciphertext or vice versa. The key is a piece of changeable data that is provided into a cryptographic method to perform this sort of activity. The security of cryptographic technology is dependent on the security of the keys used.
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