A new ring signature scheme with signer-admission property

1
A new ring signature scheme with signer-admission
property

• Chih-Hung Wang, Chih-Yu Liu
• Information Sciences, Volume 177, Issue 3, 1
  February 2007, Pages 747-754
• Presenter ???

2
Outline

• Introduction
• Ring signature
• Proposed scheme
• Conclusion

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Introduction

• Ring signature is a simplified group signature
  was proposed in 2001
• Two properties of ring signature
• Signer-ambiguity
• Setup-free
• This paper constructs signer-admission property
  into ring signature

4
Ring signature
5
Ring signature (conti.)
Signer (users)
Verifier
1.Compute kh(m)2.Pick a random glue value
v3.Pick random xi , 1?i ?r, i?s and compute
yigi(xi)4.Solve Ck,v(y1,y2,...ys...yr)v5.Compu
te xsgs-1(ys)
1.Compute yigi(xi) , for i1,2,...,r2.Compute
kh(m)3.Verify the following equation
Ck,v(y1,y2,...ys...yr)v
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Proposed scheme(1/4)

• Signature generation
• Let the signer is As and the message is m
• Choose s,z ,and compute agsmod p and baz mod p
• Compute symmetric key kh(m?a) ?b
• Choose w ,and compute Raw mod p and
  ewz.F(m?a,R) mod p

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Proposed scheme(2/4)

• Pick random xi , 1?i ?r, i?s and compute
  yigi(xi)
• Choose random value v and solve
  Ck,v(y1,y2,...ys...yr)v
• Compute xsgs-1(ys)
• Output ring signature (P1,P2,..,Prvx1,x2,..,xr
  a,b,R,e)

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Proposed scheme(3/4)

• Signature verification

• Let the signer is As and the message is m
• Check whether aeR.bF(m?a ,R) mod p
• compute yigi(xi) for i1,2,...,r
• kh(m?a) ?b
• Verify the following equation Ck,v(y1,y2,...ys...y
  r)v

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Proposed scheme(4/4)

• Signer-admission

Signer (users)
Designated verifier
1.Randomly choose ?,t2.Compute ?a?mod
p3.Compute commitment c g?PKvt mod p
c
Randomly choose d
d
??z d (mod p)
?, t , ?
Checkcg?PKvt mod pa??bd mod p
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Conclusion

• Proposed an extended ring signature with a
  signer-admission property
• Using designated verifier proof to achieve
  signer-admission property