Distributed Identity Based Short Linkable Ring Signature Kasra - PowerPoint PPT Presentation

Distributed Identity Based Short Linkable Ring Signature Kasra EdalatNejad Prof. Bryan Ford DEcentralized and DIstributed Systems

Goal ● Anonymity ● Accountability ● Usability 2

Ring Signature Anonymous Spontaneous 3

Linkable Ring Signature ● Event tag ● Accountable ● Linear size 4

Cryptographic Accumulator ● Make a short representation ● Not a compresion 5

Accumulator ● Accumulate set(X): V ● Generate witness: W ● Check membership: (x, W, V) 6

Additional properties ● Dynamic ● Authority 7

Bilinear Pairing (Nguyen) ● Master Secret Key: s ● Publicly computable 8

Bilinear Pairing (Nguyen) ● With Authority: Dynamic ○ Authority ○ ● No Authority: Trusted setup ○ Not efficient ○ 9

Accumulator VS Ring Signature 10

Short Linkable Ring Signature ● Membership in ring ● Knowing private key ● Correct link tag 11

Identity Based Cryptography ● Public key is based on name ● No Certificate Authority ● Authority generate private key ● Key escrow 12

Bilinear pairing SLRS ● Membership: Nguyen’s Accumulator ● Knowledge of private key: Sakai-Kasahara IBC ○ ○ ● Link 13

Secret Sharing: Direct ● Shamir polynomial ● Distributed key generation ● Compute: 14

Secret sharing: inverse ● Compute: ● Secure Multiparty Computation ● Online participation for each request ● Not efficient 15

Distributed IBC ● Use SS inverse ● Distributed trust 16

Distributed Nguyen’s Acc ● Trusted setup ● Distributed trust SS Direct: Week dynamic ○ SS Inverse: Fully dynamic ○ 17

Distributed Accumulator None SS Direct SS Inverse Accumulate: Witness generation No check witness: Add member Remove member 18

Idea ● Hierarchical Accumulator Improve efficiency in non-trusted model ○ ● Hierarchical SLRS Different privacy levels ○ Set management ○ 19

Voting ● Different levels: City, Canton, Country ● Autonomous sets ● Unique identity link across levels 20

PoP Party ● Merging parties ● Removing parties ● Attribute based parties ● Multiple attributes for a party ● Distinct parties? Same IBC authority? 21

Challenges ● Efficiency ● Efficiency ● Efficiency 22

Summary ● Accumulator ● Linkable Ring Signature ● Identity Based Cryptography ● Distributed Authority ● Distributed Identity Based Short Linkable Ring Signature (DIBSLRS) 23

RSA ● Accumulator ● Short Linkable Ring Signature (SLRS) ● Authority ● Certificate public key 24