View
231
Download
1
Category
Preview:
Citation preview
Efficient and Secure Identity-Based Signatures and
Signcryption from Bilinear Maps
Paulo Barreto, Benoit Libert, Noel McCullagh and Jean-Jacques
QuisquaterPresented by Mike Scott
A new Identity-Based Signature Scheme
• Based on Sakai-Kasahara construction
– Generators P, Q, g=e(P,Q), Master secret s, and Qpub=sQ, hash functions H1 and H2
• Keygen
– D=1/(H1(ID)+s).P generates private key D from Identity ID and TA’s secret s
A new Identity-Based Signature Scheme
• Signature– r=gx, for random x
– h=H2(M,r), to sign a message M
– S=(x+h)D, where D is the private key– Signature is (h,S)
A new Identity-Based Signature Scheme
• Verification– Signature (h,S) is accepted iff
– h = H2(M,e(S,H1(ID)Q+Qpub).g-h)
A new Identity-Based Signcryption Scheme
• Parameters as before (with another hash function H3). Key generation as before.
• Sign/Encrypt from Alice to Bob– r=gx for random x, c=M H3(r) – h=H2(M,r) – S=(x+h)DA, where DA is the senders private
key– T=x(H1(IDB)P+Qpub), where IDB is recipient– Ciphertext is (c,S,T)
A new Identity-Based Signcryption Scheme
• Decrypt/Verify– Compute r = e(T,DB), M=cH3(r), h=H2(M,r)
– Accept iff
– r = e(S,H1(IDA)Q+Qpub)g-h
Features
• Fast and very efficient
• No pairings for Sign/Encrypt
• “Better than all the rest” – Tina Turner
• Implemented and tested
• Security proofs
• Anonymity support
Recommended