pyUmbral is a python implementation of David Nuñez’s threshold proxy rencryption scheme: Umbral. Implemented with OpenSSL and, pyUmbral is a referential and open-source cryptography library extending the traditional cryptological narrative of “Alice and Bob” by introducing a new actor, Ursula, who has the ability to take secrets encrypted for Alice and re-encrypt them for Bob.


  • Re-encryption Toolkit
  • Re-encryption Key Fragmentation
  • Key Encapsulation
  • Elliptic Curve Arithmetic

Academic Whitepaper

The Umbral scheme academic whitepaper and cryptographic specifications are availible on GitHub.

“Umbral A Threshold Proxy Re-Encryption Scheme” by David Nuñez

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