<p>The four-volume set, LNCS 16551-16554, constitutes the refereed proceedings of the 29th IACR International Conference on Practice and Theory of Public-Key Cryptography, held in West Palm Beach, FL, USA, during May 25–28, 2026.</p><p>The 65 papers included in these proceedings were carefully reviewed and selected from 259 submissions. They are organized in topical sections as follows:<br>Part I: Lattice Foundations and KEM; Signature Schemes; Cryptanalysis<br>Part II: Foundations and Security Definitions; MPC and Friends; Commitments<br>Part III: Isogenies and Curves; Proof Systems and Functional Encryption; Credentials and Advanced Signatures<br>Part IV: Advanced Encryption and Privacy; Homomorphic and Searchable Encryption; Protocols and Real-World Security</br></br></br></br></p>