A Simple Compiler for CCA2-Secure Pseudorandom Codes in the Standard Model

Nico Döttling; Antoine Joux; Venkata Koppula; Mahesh Sreekumar Rajasree; Hendrik Waldner

Paper 2026/1867

A Simple Compiler for CCA2-Secure Pseudorandom Codes in the Standard Model

Nico Döttling

, Helmholtz Center for Information Security

Antoine Joux

, Helmholtz Center for Information Security

Venkata Koppula

, Indian Institute of Technology Delhi

Mahesh Sreekumar Rajasree

, Helmholtz Center for Information Security

Hendrik Waldner

, Helmholtz Center for Information Security

Abstract

Public-key pseudorandom codes (PRCs) combine two seemingly conflicting properties: their codewords are computationally indistinguishable from uniformly random strings, yet a secret-key decoder can recover the encoded message even after a bounded Hamming corruption. Security against chosen-plaintext (CPA) attacks asks that an encoding of a chosen message appears uniform. Security against adaptive chosen-ciphertext (CCA2) attacks additionally gives the adversary adaptive access to a decoding oracle for codewords outside the Hamming ball around the challenge encoding. Döttling et al. (CRYPTO 2026) showed how to realize CCA2-secure PRCs in the standard model through a generic compiler based on the Koppula-Waters hinting pseudorandom generator framework. We give a substantially simpler black-box compiler. Starting from any adaptively $\alpha$-robust, CPA-pseudorandom PRC and using only a secure PRG and an almost perfectly correct IND-CCA2-secure PKE scheme, our compiler constructs an adaptively $\alpha/2$-robust, $\alpha/2$-CCA2-pseudorandom PRC. The compiled PRC has twice the codeword length of the underlying PRC and therefore loses only a factor of two in its relative decoding radius; in particular, it preserves a constant relative decoding radius.

Metadata

Available format(s): PDF
Category: Foundations
Publication info: Preprint.
Keywords: Psuedorandom Codes CCA-Security Standard Model
Contact author(s): doettling @ cispa de
joux @ cispa de
kvenkata @ iitd ac in
srmahesh1994 @ gmail clom
hendrik waldner @ cispa de
History: 2026-09-06: approved; 2026-09-02: received; See all versions
Short URL: https://ia.cr/2026/1867
License: CC BY

BibTeX

@misc{cryptoeprint:2026/1867,
      author = {Nico Döttling and Antoine Joux and Venkata Koppula and Mahesh Sreekumar Rajasree and Hendrik Waldner},
      title = {A Simple Compiler for {CCA2}-Secure Pseudorandom Codes in the Standard Model},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/1867},
      year = {2026},
      url = {https://eprint.iacr.org/2026/1867}
}