Overview
ISO 9564-2:2025 - part of the ISO 9564 series on PIN management and security - specifies the approved algorithms for encipherment of Personal Identification Numbers (PINs) in financial services. The standard defines which symmetric and asymmetric ciphers are permitted for different PIN block formats and use cases, and gives guidance on key encapsulation, key derivation and replay protection when using asymmetric techniques to transport ephemeral PIN encryption keys.
Key topics and requirements
- Approved algorithms: TDEA (Triple DES), RSA, AES, SM4, and ECIES (elliptic curve integrated encryption scheme).
- Modes and block sizes:
- TDEA: ECB mode, n = 64; keying option 1 or 2. Approved only for PIN block formats 0, 1 and 3. TDEA is increasingly considered unsafe and should be avoided in new implementations.
- AES and SM4: ECB mode, n = 128. Approved for PIN block format 4 only.
- RSA: Defined per ISO/IEC 18033‑2. Approved for offline PIN submission to ICCs (PIN block format 2) and for PIN issuance/change over open networks.
- ECIES: Hybrid (ECIES‑HC) using an ECIES‑KEM, a KDF (ISO/IEC 11770‑6 or KDF1/KDF2), and a DEM based on AES or SM4 with authenticated encryption per ISO/IEC 19772. Approved only for offline PINs to ICCs (format 2); not for direct online PIN encryption.
- Key management: All PIN keys and encapsulation mechanisms must comply with ISO 11568 (retail key management). Randomness must meet ISO/IEC 18031.
- Annex A guidance: Practical advice on using key encapsulation mechanisms (KEMs/RSA‑KEM/ECIES‑KEM) to transport ephemeral symmetric PIN keys, acceptable KDFs, replay protection techniques (nonces, transaction binding, MACs/signatures), and allowed PIN block formats when using encapsulated keys.
Practical applications and who uses this standard
- Financial institutions, acquirers, issuers and payment processors implementing secure PIN transport and storage.
- Vendors of PIN entry devices (PEDs), HSMs, POS terminals, and payment gateways integrating PIN encryption.
- Card manufacturers and IC (chip) card developers implementing offline PIN verification.
- Security architects, compliance teams and auditors who must ensure cryptographic choices meet industry and regulatory requirements.
Use cases include online PIN transmission, offline PIN submission to IC cards, issuance/change of PINs over open networks, and secure key exchange to establish ephemeral PIN encryption keys.
Related standards (for implementation)
Keywords: ISO 9564-2:2025, PIN encipherment, PIN management, TDEA, AES, SM4, RSA, ECIES, PIN block formats, key encapsulation, ISO 11568.
Open preview (PDF)Financial services — Personal Identification Number (PIN) management and security — Part 2: Approved algorithms for PIN encipherment
