Filter
Top Products
Security Software—Intel
®
QuickAssist Technology Cryptographic API Architecture Overview
Intel
®
EP80579 Software for Security Applications on Intel
®
QuickAssist Technology
PG August 2009
24 Order Number: 320183-004US
Note: Exclusive disjunction (usual symbol xor) is a logical operator that results in true if one
of the operands (not both) is true.
Counter mode turns a block cipher into a stream cipher, as shown in Figure 6. It
generates the next keystream block by encrypting successive values of a "counter".
The counter can be any simple function which produces a sequence which is
guaranteed not to repeat for a long time, although an actual counter is the simplest
and most popular.
Figure 5. Cipher-Block Chaining (CBC) Mode
Plaintext
block [0]
(64/128 bits)
Encryption
Ciphertext
block [0]
(64/128 bits)
Initialization
Vector (IV)
(64/128 bits)
Plaintext
block [1]
(64/128 bits)
Encryption
Ciphertext
block [1]
(64/128 bits)
Plaintext
block [2]
(64/128 bits)
Encryption
Ciphertext
block [2]
(64/128 bits)
XOR XOR XOR
Figure 6. Counter Mode
Encryption
Ciphertext block
[0]
(128 bits)
Plaintext
block [0]
(128 bits)
Key
1
Encryption
Ciphertext block
[1]
(128 bits)
Plaintext
block [1]
(128 bits)
Key
2
Encryption
Ciphertext block
[2]
(128 bits)
Plaintext block
[2]
(128 bits)
Key
XOR XOR XOR
0