2
Optimized for
CS5010-40 DES/3DES Encryption/Decryption Cores
APPLICATIONS
♦ Electronic financial transactions
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eCommerce
-Banking
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Securities exchange
-
Point-of-Sale
♦ Secure corporate communications
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Storage Area Networks (SAN)
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Virtual Private Networks (VPN)
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Video conferencing
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Voice services
♦ Personal mobile communications
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Video phones
-PDA
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Point-to-Point Wireless
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Wearable computers
♦ Secure environments
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Satellite communications
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Surveillance systems
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Network appliances
DATA ENCRYPTION ALGORITHM
The Data Encryption Algorithm is an iterated block cipher
with a Feistel structure that encrypts and decrypts data in 64-
bit data blocks using a 56-bit key. The algorithm consists of:
•
An initial permutation of the input data
•
Sixteen rounds of the same process - the DES round
•
A final inverse initial permutation of the data
Figure 2 represents a block diagram of the Data Encryption
Algorithm. A DES round transforms the data using
permutations, additions and non-linear substitutions. The
DES key schedule consists of three parts:
1.
Key Permutation - to remove the eight redundant parity
bits within the 64-bit key, and to permute the key
2.
Scheduled Circular Shifting - the permuted key is circu-
larly shifted according to a schedule by either 1 or 2 bits,
to the left or right.
3.
Key Compression - the 56-bit shift key is compressed
using another permutation, or rearrangement, to obtain a
48-bit subkey.
The Triple Data Encryption Algorithm offers increased
security by extending the DES key to 112 or 168 bits, thus
greatly reducing the effectiveness of exhaustive key searches
or "brute-force" attacks. Triple DES is simply three successive
DES operations in the sequence of encrypt-decrypt-encrypt, or
decrypt-encrypt-decrypt if decrypting data.
Figure 2: DES Algorithm Structure
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