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Unformatted text preview: MAC.
Why is it insufficent to just append the CBC residue of the 1st pass as the
MAC Drawbacks of using Encryption for MAC Encryption software is slow
Encryption hardware costs aren’t cheap
Hardware optimized toward large data sizes
Encryption Algorithms are usually covered by patents
Algorithms subject to US export control
export One-Way Hash Function Hash function accepts a variable size message M as input and
produces a fixed-size message digest H(M) as output
Message digest is sent with the message for authentication
Produces a fingerprint of the message
No secret key is involved MAC generation using One Way Hash +
Conventional encryption Message digest H(M) Shared key Authenticity is assured ; no confidentiality is provided;
Still need Encryption algorithm ; but faster because the hash function
computation is quicker than encrypting the entire message ; now only
need to encrypt
The much shorter message digest instead Use only One Way Hash Function to
Secret value SAB MDM||M MDM = H(M ||
Would MDM = H(SAB || M ) work as well ? The Answer is...
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This note was uploaded on 12/05/2013 for the course IERG 4130 taught by Professor Chowsze-ming,sherman during the Fall '13 term at CUHK.
- Fall '13