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Private Key Encryption


Private keys are known as symmetrical keys. In private key encryption technology, both the sender and receiver have the same key and use it to encrypt and decrypt all messages. This makes it difficult to initiate communication the first time. How do you securely transmit the single key to each user? You use public keys, which we’ll discuss shortly.

The Data Encryption Standard (DES)


International Business Machines (IBM) developed one of the most commonly used private key systems, DES. In 1977, the United States made DES a government standard, defined in the Federal Information Processing Standards Publication 46-2 (FIPS 46-2).


DES uses lookup table functions and is incredibly fast when compared with public key systems. A 56-bit private key is used. RSA Data Systems issued a challenge to break the DES. Several Internet users worked in concert, each tackling a portion of the 72 quadrillion possible combinations. The key used in RSA’s challenge was broken in June 1997, after searching only 18 quadrillion keys out of the possible 72 quadrillion. The plain text message read: “Strong cryptography makes the world a safer place.”

Skipjack and Clipper


The replacement for DES might be the NSA’s recent algorithm called skipjack. Skipjack is officially called the Escrowed Encryption Standard (EES), defined in FIPS 185, and uses an 80-bit key rather than the DES 56-bit key.


The functions and complexity of each algorithm are different as well. Classified as secret (or classified) by the NSA, the skipjack formulas remain unknown. Skipjack was supposed to be integrated into the clipper chip.

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