In
cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...
, Post-Quantum Extended Diffie–Hellman (PQXDH) is a
Kyber
Kyber is a key encapsulation mechanism (KEM) designed to be resistant to cryptanalysis, cryptanalytic attacks with future powerful quantum computing, quantum computers. It is used to establish a shared secret between two communicating parties wit ...
-based
post-quantum cryptography
Post-quantum cryptography (PQC), sometimes referred to as quantum-proof, quantum-safe, or quantum-resistant, is the development of cryptographic algorithms (usually public-key algorithms) that are currently thought to be secure against a crypt ...
upgrade to the
Diffie–Hellman key exchange
Diffie–Hellman (DH) key exchangeSynonyms of Diffie–Hellman key exchange include:
* Diffie–Hellman–Merkle key exchange
* Diffie–Hellman key agreement
* Diffie–Hellman key establishment
* Diffie–Hellman key negotiation
* Exponential ke ...
. It is notably being incorporated into the
Signal Protocol, an
end-to-end encryption
End-to-end encryption (E2EE) is a method of implementing a secure communication system where only communicating users can participate. No one else, including the system provider, telecom providers, Internet providers or malicious actors, can ...
protocol.
In September 2023, the developers of the Signal Protocol announced that it was being updated to support PQXDH.
PQXDH is an upgraded version of the
X3DH protocol and uses both the quantum-resistant CRYSTALS-Kyber protocol as well as the old elliptic curve
X25519 protocol. This ensures that an attacker must break both of the encryption protocols to gain access to sensitive data, mitigating potential security vulnerabilities the new protocol could have. The protocol is designed for asynchronous communication where the clients exchange
public keys through a
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides requested information for other programs or devices, called clients.
Role
* Waiting staff, those who work at a restaurant or a bar attending custome ...
to derive a secure
shared key which they can use to encrypt sensitive data without needing to constantly sync new keys with each other.
In October 2023, the protocol underwent
formal verification
In the context of hardware and software systems, formal verification is the act of proving or disproving the correctness of a system with respect to a certain formal specification or property, using formal methods of mathematics.
Formal ver ...
which managed to "prove all the desired security properties of the protocol" for its second revision.
See also
*
Post-quantum cryptography
Post-quantum cryptography (PQC), sometimes referred to as quantum-proof, quantum-safe, or quantum-resistant, is the development of cryptographic algorithms (usually public-key algorithms) that are currently thought to be secure against a crypt ...
*
Shor's algorithm Shor's algorithm is a quantum algorithm for finding the prime factors of an integer. It was developed in 1994 by the American mathematician Peter Shor. It is one of the few known quantum algorithms with compelling potential applications and strong ...
*
Signal Protocol
*
Signal (software)
Signal is an American open-source, encrypted messaging service for instant messaging, voice calls, and video calls. The instant messaging function includes sending text, voice notes, images, videos, and other files. Communication may be one- ...
*
Public-key cryptography
Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic alg ...
*
End-to-end encryption
End-to-end encryption (E2EE) is a method of implementing a secure communication system where only communicating users can participate. No one else, including the system provider, telecom providers, Internet providers or malicious actors, can ...
*
Cryptanalysis
Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ...
*
Diffie–Hellman key exchange
Diffie–Hellman (DH) key exchangeSynonyms of Diffie–Hellman key exchange include:
* Diffie–Hellman–Merkle key exchange
* Diffie–Hellman key agreement
* Diffie–Hellman key establishment
* Diffie–Hellman key negotiation
* Exponential ke ...
*
Symmetric-key algorithm
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between ...
References
External links
The PQXDH Key Agreement Protocol
Public-key cryptography
Cryptographic protocols
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