6.cryptographic-protocols

# 6.cryptographic-protocols - Cryptographic Protocols Entity...

This preview shows pages 1–12. Sign up to view the full content.

Cryptographic Protocols ■ Entity Authentication ■ Key Agreement ■ Fiat-Shamir Identification Schemes ■ Zero-Knowledge Proof Systems ■ Shnorr’s Identification/Signature Scheme ■ Commitment Schemes ■ Secret Sharing ■ Electronic Election

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Click to edit Master subtitle style Entity Authentication Problem: Alice wants to prove to Bob that she is Alice and/or vice versa. Private-key based schemes Public-key based schemes Integrated with key agreement Zero-knowledge identification schemes
( ): 1. Bo Protoco b Alice: a random challenge . 2. Bob Alice: Alice and Bob share MAC ( ) a secret key . insec . 3. Bob computes M ure AC ( ) and c l Challenge-and-response using a private key k k r y r y r k = = hecks if . 1. Bob Alice: a random challenge . 2. Bob Alice: ( ). 3. O Bob checks if ( r ) . k k y y r y E r D y r = = =

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
MA C ( ) Parall el sessio Ev n attack Bob e k r y r y r = ←  → → ←
M Bob MAC ( Ali A ( ) ce)? C Countermeasure Bo ve b E k k r y r y r r = = → ←    P P

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
( ): 1. Bob Alic Alice and Bob share a secret key . sec Protocol ID e: a random challenge . 2. Bob Alice: MAC ( ). 3. Bob comput (Alic u e) es MAC ( re Challenge-and-response using a private key k k r k y r y = = P ) and checks if . 1. Bob Alice: a random challenge . 2. Bob Alice: (ID(Alice) ). 3. Bob checks if ( ) I ID(Alice) D(Alice) . Or k k r y y r y E r D y r = = = P P P
1 2 1 1 Alice and Bob share a secret key . : 1. a random challeng Bob Alice: . 2. Bob Alice: 3. Bob Ali Pr ce: insecure and o e MAC tocol ( (ID(Alice) ) ) . Mutual authentication using a private key k y k r r r = P 2 2 4. Alice and Bob verify each M other's response AC (ID(Bob) ) . . k y r = P

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
1 3 2 2 2 1 MAC (B ), MAC (A ), MA Man-in- the-middle attack Eve A lice Bob k k r r r r r r ← → → ← P P 2 C (B ) k r ← P
2 1 1 3 2 2 3 2 MAC (A ) MAC (B ), MAC , (B C ountermeasure A Bo lic b E e ve k k k r r r r r r r r ← → → ← P P P P 2 )? r ← P

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
1 2 2 1 1 ( ): 1. Bob Alice: a r Alice and Bob share a secret key . secure andom challenge . 2. Bob Alice: MAC (ID(Alice) ) and . 3. Bob Al P i rotocol ce: Mutual authentication using a private key k k r y r r r = P P 2 2 2 2 1 MAC (ID(Bob) ). 4. Alice and Bob verify each other's response. 3 . Bob Alice: Alternati MAC (ID(Bob) ). vely: k k y r y r r = = P P P
1 (Allice) (Bob 1 1 2 ) 2 2 2 ( ): 1. Bob Alice: a random challenge . 2.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 101

6.cryptographic-protocols - Cryptographic Protocols Entity...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online