An Efficient and Secure Event Signature (EASES) Protocol for Peer-to-Peer Massively Multiplayer Onli...
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An Efficient and Secure Event Signature (EASES) Protocol for Peer-to-Peer Massively Multiplayer Online Games Mo-Che Chan, Shun-Yun Hu and Jehn-Ruey Jiang Adaptive Computing and Networking Lab. National Central University. Outline. Background Related work NEO SEA The proposed scheme EASES

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An Efficient and Secure Event Signature (EASES) Protocol for Peer-to-Peer Massively Multiplayer Online GamesMo-Che Chan, Shun-Yun Hu and Jehn-Ruey JiangAdaptive Computing and Networking Lab.National Central University


Outline

  • Background

  • Related work

    • NEO

    • SEA

  • The proposed scheme

    • EASES

  • Evaluation

  • Conclusion


Background - MMOG

  • Multiplayer online game

  • Massively multiplayer online game (MMOG)


Background - architectures

  • Client-server


Background - architectures

  • Server-cluster


Background - architectures

  • Peer-to-peer (P2P) network

  • Efficiently maintain the topology

    • Virtual environment


Background – game logic

  • In client-server and server-cluster

    • Server maintains game states

    • Users send event to server

    • Server sends information to player

round

time

7


Background – cheat problem

  • Game logic is maintained by peers in P2P environments.

  • Some players may gain advantages unfairly.


Background - commitment

  • Play the paper, scissors, rock game remotely without arbiter


Background – hash function

  • Cryptographic hash function

  • Strength depends on the following infeasibilities

    • For any given hashed value, to find M or M’

    • For any given message M, to find H(M) = H(M’)

    • To find any pair (M, M’) such that H(M) = H(M’)

Hash function

010101110100


Background - commitment

  • No one can get unfair advantages if the hash function is secure.

H(Choice | Random)

H(Choice | Random)

Choice | Random

Choice | Random

First send H(Choice | Random)

Then send (Choice | Random)


Background – digital signature

  • Concept

010101000111010011001011

010011100110101000110101

011010111000110101010100

110100011010101010101001

010101010010101010101010

……..

101001110100110010110110

101100110101000110101010

010111001011010101010011

010010110101010101010010

110110010101010101010111

……..

Signature

algorithm

A document

To sign it

A digital signature

  • No one can forge

  • Signer can’t repudiate that he executed the algorithm for this document

  • Authenticity of the document


Background – digital signature

  • To sign a message

To sign by sender’s

private key

Hash function

message

0101…101

1011…110

message

1011…110


Background – digital signature

  • To verify a signature

message

1011…110

To inverse the signature

by signer’s public key

Hash function

?

0101…101

0101…101

To check they are the same or not


Related work - NEO

  • Every updating message

    • Signing event updating message

    • Encrypting the signed message

  • After, send decrypting key

Player i


Related work - SEA

  • Every updating message

    • Signed hash value of event updating message

  • After, send the plain message

Player i


The problem that we observed

  • Digital signature algorithms are too slow.

To sign the

message digest

Single

Document

Hash algorithm

Signature algorithm

To produce the

message digest

Original message

Signature


The objective

  • To efficiently sign many discrete messages

Message 1

Message 2

……

Message n


The proposed EASES

  • Initialization phase

    • Every player prepares the keys for signing.

  • Signing phase

    • Every player signs his messages.

  • Verification phase

    • Every receiver verifies the authenticity.

  • Re-initialization phase

    • Re-generate new signing keys.


EASES – initialization phase

……..

1011…110


EASES – signing & verification

…….

Send out

j-2

j-1

j

j

j+2

j+1

j-1

j

j-2

j-3

j-2

j-1

…….

j

j+1

j+2

j-3

j-2

j-1


EASES – re-initialization phase

  • Re-execute initialization phase

  • A more efficient way

    • Reserve the last two keys

……..

……..

1011…110


Evaluation - performance

  • Computational cost

    • Hash replaces signature function

  • Memory consumption

    • 1,000 * 192 bits = 24,000 bytes, when n = 1,000

  • Bandwidth consumption

    • Length of Hash value is short than signature’s


Evaluation - security

  • Unforgeability

    • No one can claim that he signed M, unless he show the OSK of M.

    • This requirement is secure if adopted cryptographic hash function is secure.

  • Verifiability

    • Hash function is public.


Conclusion and discussion

  • EASES is proposed to sign many discrete messages at once efficiently

  • Security of EASES is as strong as those of traditional signature schemes

  • ESAES implies the commitment property


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