The document describes the Nymble blocking system, which allows websites to selectively blacklist users of anonymizing networks without seeing their IP addresses. It maintains users' anonymity while blocking blacklisted users from future connections. The system architecture includes users, a pseudonym manager, Nymble manager, and servers. It aims to achieve blacklistability, rate-limiting, nonframeability, and anonymity.

1. 1

3.  Introduction
 Nymble
 Properties
 System Architecture
 Security Model
 Limitations
 Conclusion
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4.  Anonymous network
o IP hiding facilities
o Polipo, Tor, USAIP
 Users misuses this network for abuse
 They deface popular websites
 Websites cannot blacklist individual IP
address
 They blacklist entire anonymizing network
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5.  In pseudonymous credential systems
Users are added to a blacklist
Weak in anonymity
 In anonymous credential system
Group signatures
Lacks scalability
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6.  A system that allows websites to selectively
blacklist users of anonymizing networks.
 Blocks user without user's IP-address.
 Legitimate users enjoy anonymity.
 Blacklisted users got blocked for future
connections.
 Previous connections remain unlinkable.
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7.  Anonymous Authentication
 Backward Unlinkability
 Subjective Blacklisting
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8.  Fast Authentication Speeds
 Rate-Limited Anonymous Connections
 Revocation Auditability
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9.  User
 The Pseudonym Manager
 The Nymble Manager
 Server
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10. Fig. The Nymble system architecture showing the various modes of interaction
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11. Fig: The Nymble system architecture showing how a user is blacklisted
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12. Nymble Blocking System 12

13. Aims four security goals
 Blacklistability
 Rate-limiting assures
 Nonframeability
 Anonymity
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14.  Sybil attack
 Mimics IP based blocking
 Availability of multiple IP address helps
users circumvent the system
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15.  Nymble is comprehensive credential system.
 Add a layer of accountability to any publicly known
anonymizing network.
 Servers blacklist misbehaving users maintaining their
privacy.
 Increase the mainstream acceptance of anonymizing
network.
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16.  www.airccse.org
 www.torproject.org
 www.sciencedirect.com
 www.wikipedia.com
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17. Nymble Blocking System
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