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In cryptography, CECPQ1 (combined elliptic-curve and post-quantum 1) is a post-quantum key-agreement protocol developed by Google as a limited experiment[1] for use in Transport Layer Security (TLS) by web browsers.[2] It was succeeded by CECPQ2.


CECPQ1 was designed to test algorithms that can provide confidentiality even against an attacker who possesses a large quantum computer. It is a key-agreement algorithm for TLS that combines X25519 and NewHope, a ring learning with errors primitive. Even if NewHope were to turn out to be compromised, the parallel X25519 key-agreement ensures that CECPQ1 provides at least the security of existing connections.[2]

It was available in Google Chrome 54 beta.[3] In 2016, its experimental use in Chrome ended and it was planned to be disabled in a later Chrome update.[4]

It was succeeded by CECPQ2.

See also[edit]


  1. ^ "Experimenting with Post-Quantum Cryptography". Google Online Security Blog. Retrieved 2020-12-26.
  2. ^ a b "Chrome: Stop future computers from cracking current encryption". CNET.
  3. ^ "Chrome 54 Beta Brings Custom Elements V1: Create Custom HTML Tags - Phoronix". Phoronix.
  4. ^ "CECPQ1 results (28 Nov 2016)". Adam Langley, security officer at Google.