liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms.
Impact
The HQC algorithm has a theoretical design flaw which leads to large numbers of malformed ciphertexts sharing the same implicit rejection value. Currently, no concrete attack on the algorithm is known. However, prospective users of HQC must take extra care when using the algorithm in protocols involving key derivation. In particular, HQC does not provide the same security guarantees as Kyber or ML-KEM.
Patches
There is currently no patch available in liboqs. OQS will update its implementation after the HQC team releases an updated algorithm specification. HQC is disabled by default in liboqs starting from version 0.13.0.
References
The OQS team became aware of this issue via a report from Markku-Juhani O. Saarinen to the NIST pqc-forum mailing list. The issue had been previously noted and analyzed on the blog of Deirdre Connolly.
mjosaarinen Reporter
liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms.
Impact
The HQC algorithm has a theoretical design flaw which leads to large numbers of malformed ciphertexts sharing the same implicit rejection value. Currently, no concrete attack on the algorithm is known. However, prospective users of HQC must take extra care when using the algorithm in protocols involving key derivation. In particular, HQC does not provide the same security guarantees as Kyber or ML-KEM.
Patches
There is currently no patch available in liboqs. OQS will update its implementation after the HQC team releases an updated algorithm specification. HQC is disabled by default in liboqs starting from version 0.13.0.
References
The OQS team became aware of this issue via a report from Markku-Juhani O. Saarinen to the NIST pqc-forum mailing list. The issue had been previously noted and analyzed on the blog of Deirdre Connolly.