Cryptography

Enhanced Definition

Cryptography on z/OS refers to the practice and study of secure communication techniques, primarily involving the use of mathematical algorithms and specialized hardware to protect data from unauthorized access, modification, or disclosure. It ensures data confidentiality, integrity, authentication, and non-repudiation for sensitive information processed and stored on IBM mainframe systems.

Key Characteristics

- Hardware Acceleration: z/OS heavily leverages dedicated cryptographic coprocessors (e.g., Crypto Express adapters) on zSystems for high-performance, secure execution of cryptographic operations, offloading CPU cycles.
- Integrated Cryptographic Service Facility (ICSF): ICSF is the primary z/OS component that provides an application programming interface (API) for cryptographic services, acting as the interface between applications and the hardware cryptographic features.
- Robust Key Management: Features comprehensive key management capabilities, including secure generation, storage, distribution, and revocation of cryptographic keys, often integrated with RACF and external key managers.
- Standards Compliance: Supports a wide range of industry-standard cryptographic algorithms (e.g., AES, RSA, ECC, SHA) and protocols (e.g., TLS/SSL, IPsec), complying with regulations like FIPS 140-2.
- Data at Rest and In Transit Protection: Provides mechanisms to encrypt data stored on disk (e.g., DFSMS data set encryption) and data transmitted across networks (e.g., TCP/IP TLS/SSL).
- Digital Signatures and Hashing: Enables the creation and verification of digital signatures for data integrity and authenticity, and uses hashing for password storage and data integrity checks.

Use Cases

- Data Set Encryption: Encrypting sensitive VSAM, sequential, or PDS/E data sets at rest using DFSMS data set encryption to protect against unauthorized access to storage media.
- Secure Network Communications: Implementing TLS/SSL for secure communication channels for applications like CICS web services, DB2 client connections, FTP, TN3270, and z/OS Connect.
- Database Encryption: Encrypting sensitive columns or entire tables within DB2 for z/OS or IMS databases to protect highly confidential information.
- Digital Signatures for Code Integrity: Signing z/OS UNIX executables, Java applications, or configuration files to ensure their authenticity and integrity, preventing tampering.
- User and Application Authentication: Utilizing digital certificates, managed by RACF and ICSF, for strong authentication of users, applications, and systems accessing z/OS resources.

Related Concepts

Cryptography is foundational to ICSF (Integrated Cryptographic Service Facility), which is the central software component that provides cryptographic services on z/OS, interfacing with the hardware. It integrates closely with RACF (Resource Access Control Facility) for managing access to cryptographic keys, key rings, and services, and for certificate management. Cryptography is also essential for PKI (Public Key Infrastructure) on z/OS, enabling digital certificates and secure communication. Furthermore, it underpins DFSMS (Data Facility Storage Management Subsystem) for data set encryption and TCP/IP for secure network protocols like TLS/SSL.

Best Practices:

Leverage Hardware Cryptography: Always utilize the dedicated cryptographic hardware (Crypto Express adapters) on zSystems for all sensitive cryptographic operations to ensure optimal performance and the highest level of security.
Implement Strong Key Management: Establish robust key management policies and procedures, including secure key generation, storage (e.g., in ICSF PKA/CCA key data sets), rotation, and revocation, integrating with external key managers where appropriate.
Use Strong, Current Algorithms: Adhere to industry-standard, strong cryptographic algorithms (e.g., AES-256, SHA-256/512, RSA 2048-bit or higher, strong ECC curves) and avoid deprecated or weak algorithms (e.g., DES, MD5, SHA-1).
Regularly Audit and Monitor: Periodically audit cryptographic configurations, key usage, and access controls (via RACF) to ensure compliance with security policies and identify potential vulnerabilities or misconfigurations.
Principle of Least Privilege: Grant only the minimum necessary access to cryptographic keys, key rings, and services, ensuring that only authorized users and applications can perform cryptographic operations.