ahmeddeia
Member level 2
I think that the mode of operation benefit is :
With a symmetric key block cipher algorithm, the same plaintext block will always
encrypt to the same ciphertext block when the same symmetric key is used. If the
multiple blocks in a typical message (data stream) are encrypted separately, an
adversary could easily substitute individual blocks, possibly without detection.
Furthermore, certain kinds of data patterns in the plaintext, such as repeated
blocks, would be apparent in the ciphertext.
Cryptographic modes of operation have been defined to address this problem by
combining the basic cryptographic algorithm with variable initialization values
(commonly known as initialization vectors) and feedback rules for the information
derived from the cryptographic operation. The Recommendation for Block Cipher
Modes of Operation (NIST SP 800-38A) defines modes of operation for the
encryption and decryption of data using block cipher algorithms such as AES and
TDEA. Another part of the recommendation (SP 800-38C) defines a mode for
performing both encryption and authentication (see Section 3.3.2) in a single
operation under restricted conditions. Other modes that combine the encryption
and authentication operations are under consideration.
NIST.gov - Computer Security Division - Computer Security Resource Center
that all i understood.............can any one here give me more illustration
thanks
With a symmetric key block cipher algorithm, the same plaintext block will always
encrypt to the same ciphertext block when the same symmetric key is used. If the
multiple blocks in a typical message (data stream) are encrypted separately, an
adversary could easily substitute individual blocks, possibly without detection.
Furthermore, certain kinds of data patterns in the plaintext, such as repeated
blocks, would be apparent in the ciphertext.
Cryptographic modes of operation have been defined to address this problem by
combining the basic cryptographic algorithm with variable initialization values
(commonly known as initialization vectors) and feedback rules for the information
derived from the cryptographic operation. The Recommendation for Block Cipher
Modes of Operation (NIST SP 800-38A) defines modes of operation for the
encryption and decryption of data using block cipher algorithms such as AES and
TDEA. Another part of the recommendation (SP 800-38C) defines a mode for
performing both encryption and authentication (see Section 3.3.2) in a single
operation under restricted conditions. Other modes that combine the encryption
and authentication operations are under consideration.
NIST.gov - Computer Security Division - Computer Security Resource Center
that all i understood.............can any one here give me more illustration
thanks
