Privacy Pass

Silk - Privacy Pass Client

Client support for Privacy Pass anonymous authorization protocol.

chrome.google.com

Privacy Pass – Get this Extension for 🦊 Firefox (en-US)

Download Privacy Pass for Firefox. Client-side of the Privacy Pass protocol providing unlinkable cryptographic tokens.

addons.mozilla.org

Handles passes containing cryptographically blinded tokens for bypassing internet challenge.
The Privacy Pass extension provides users with the ability to create and sign cryptographically blind tokens for websites that support the Privacy Pass protocol. The extension generates passes containing cryptographically "blinded" tokens that are signed by the web server when a challenge page is solved. These tokens are "unblinded" and stored by the extension for future use; they are redeemed automatically when a future challenge page is seen. The "blinding" procedure means that signed and redeemed tokens are cryptographically unlinkable from the server perspective and, as such, are suitable for usage in conjunction with external privacy measures (such as VPNs).

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Privacy Pass

privacypass.github.io

Privacy Pass interacts with supporting websites to introduce an anonymous user-authentication mechanism. In particular, Privacy Pass is suitable for cases where a user is required to complete some proof-of-work (e.g. solving an internet challenge) to authenticate to a service. In short, the extension receives blindly signed ‘passes’ for each authentication and these passes can be used to bypass future challenge solutions using an anonymous redemption procedure. For example, Privacy Pass is supported by Cloudflare to enable users to redeem passes instead of having to solve CAPTCHAs to visit Cloudflare-protected websites.

The blind signing procedure ensures that passes that are redeemed in the future are not feasibly linkable to those that are signed. We use a privacy-preserving cryptographic protocol based on ‘Verifiable, Oblivious Pseudorandom Functions’ (VOPRFs) built from elliptic curves to enforce unlinkability. The protocol is exceptionally fast and guarantees privacy for the user. As such, Privacy Pass is safe to use for those with strict anonymity restrictions.

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