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Fixup prior to 0.4.0

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Sarah Jamie Lewis 2021-02-09 22:42:59 -08:00
parent 570a48f9c2
commit 1147c4f6d5
2 changed files with 31 additions and 20 deletions
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3
Cargo.toml
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@ -30,6 +30,3 @@ harness = false
[features]
entangled = ["brute-force"]

46
README.md
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@ -1,21 +1,31 @@
# FuzzyTags
Anonymous messaging systems (and other privacy-preserving applications) often require a mechanism for one party
to learn that another party has messaged them.
to learn that another party has messaged them ("notifications").
Many schemes rely on a bandwidth-intensive "download everything and attempt-decryption" approach. Others rely on a trusted
3rd party, or non-collusion assumptions, to provide a "private" service.
3rd party, or various non-collusion assumptions, to provide a "private" service. Other schemes
require that parties arrange themselves in "buckets" or "mailboxes" effectively creating smaller instances of the
"download everything" approach.
It would be awesome if we could get an **untrusted**, **adversarial** server to do the work for us without compromising metadata-resistance!
It would be awesome if we could get an **untrusted**, **adversarial** server to do the work for us
without compromising metadata-resistance or requiring parties to split themselves into buckets (effectively
dividing the anonymity set of the system)!
**fuzzytags** is an experimental probabilistic cryptographic tagging structure to do just that!
Specifically **fuzzytags** provides the following properties:
Instead of placing messages into deterministic buckets based on the recipient, **fuzzytags** allow each
message to probabilistically address itself to several parties in addition to the intended party - utilizing the
anonymity of the whole set of participants, instead of the ones who happen to share a bucket for a given round.
* Correctness: Valid tags constructed for a specific public key will always validate when tested using a derived detection key.
* Fuzziness: Tags will produce false positives with probability _p_ related to the security property (_γ_) when tested against detection keys they
were not intended for.
* Security: An adversarial server with access to the detection key **is unable to distinguish false positives from true positives**. (Detection Ambiguity)
Specifically **fuzzytags** provide the following properties:
* Correctness: Valid tags constructed for a specific tagging key will always validate when tested using a
derived detection key.
* Fuzziness: Tags will produce false positive matches with probability _p_ related to the security property (_γ_) when
tested against detection keys they were not intended for.
* Security: An adversarial server with access to the detection key **is unable to distinguish false
positives from true positives**. (this property is referred to as *Detection Ambiguity*)
## Security (hic sunt dracones)
@ -27,14 +37,21 @@ This code has not undergone any significant review.
Further, the properties provided by this system are highly dependent on selecting a **false positive rate** _p_ and
**scheme constant** _γ_ for your system. There is no one-size-fits-all approach.
If _p_ is too low, then the probability of false positives will be very high.
If _p_ is too low, then the probability of false positives for a given party will be very high.
If _p_ is too high, then an adversarial server will be able to link messages to recipients with low probability.
If _p_ is too high, then an adversarial server will be able to link messages to recipients with probability
approaching _1_.
Likewise a large _γ_ means higher bandwidth costs, but a small _γ_ reveals more of the secret keys to the server and
increases false positives.
Likewise a large _γ_ means higher bandwidth costs, but a small _γ_ reveals more of the root secret to the server while
also increasing the change of perfect (but false) matches across all parties.
## More Detailed System Description
We are also [building a simulator](https://git.openprivacy.ca/openprivacy/fuzzytags-sim) to understand these
parameter choices in addition to other factors when deploying fuzzytags to real-world systems.
For more guidance (and warnings) on integrating fuzzytags into a privacy preserving application see [documentation](https://docs.rs/fuzzytags/#integrating-fuzzytags)
## Terminology and a more detailed System Description
There exists a metadata resistant application that uses untrusted servers to mediate communication between parties.
@ -164,9 +181,6 @@ We use [criterion](https://crates.io/crates/criterion) for benchmarking, and ben
Results will be in `target/criterion/report/index.html`.
## Integrating fuzzytags
For more guidance on integrating fuzzytags into a privacy preserving application see [documentation](https://docs.rs/fuzzytags/#integrating-fuzzytags)
## Credits and Contributions