CEX6S / 4768 Overview

This page provides an overview of the IBM CEX6S - 4768 Cryptographic Coprocessor.

IBM 4768 Cryptocard

Available as IBM Z® feature CEX6S.

An IBM PCIe Cryptographic Coprocessor is a high-performance hardware security module (HSM) suitable for high-security processing and high-speed cryptographic operations. The IBM 4768 Cryptographic Coprocessor is a hardware security module (HSM) that is designed for high performance and security rich services for your sensitive workloads, and to deliver high throughput for cryptographic functions. Its predecessors are the IBM 4769 and IBM 4765. For a detailed summary of the capabilities and specifications of the IBM 4768 (formerly known as the IBM PCIeCC3), refer to the IBM 4768 Data Sheet (PDF, 262 KB).

Security Certifications

FIPS 140-2 Level 4 – Highest cryptographic security level available.

FIPS 140 defines security requirements for cryptographic modules. It is issued by the U.S. National Institute of Standards and Technology (NIST) and is widely used as a measure of the security of HSMs. The IBM 4768 is certified at Level 4 (certificate number 3410 [link resides outside of ibm.com]), the highest level of certification achievable for commercial cryptographic devices.


PCI HSM is the "Payment Card Industry Hardware Security Module" standard issued by the PCI Security Standards Council. It defines physical and logical security requirements for HSMs that are used in the finance industry. PCI HSM is one of the standards in the PCI PIN Transaction Security (PTS) device group. To view IBM firmware levels and devices that have achieved this certification, search by 'Company name' for "IBM Corporation" on the PCI PTS website (link resides outside of ibm.com).

The following list shows the IBM 4768 CCA firmware levels that have achieved PCI HSM certification on IBM Z. In the list, the "x" in ".xz" refers to the CCA maintenance level, and the "z" in ".xz" indicates that the CCA release is for IBM Z.

IBM 4768 CCA firmware levels with PCI HSM certification on IBM Z

  • CCA 6.0.xz
  • CCA 6.3.xz
  • CCA 6.6.xz

Available on IBM Z

The IBM 4768 is available on the following platform:
  • IBM Z

IBM Z Mainframe

The IBM 4768 is available as feature code (FC) 0893 (Crypto Express6S, or CEX6S) on IBM Z mainframes (z14® only), either on z/OS® or Linux® on IBM Z operating systems.
  • FC 0893 requires FC 3863 - CPACF (Central Processor Assist for Cryptographic Functions) DES/TDES Enablement. CPACF is a set of cryptographic instructions providing improved performance through hardware acceleration. Using the cryptographic hardware, you gain security from using the CPACF and the Crypto feature through in-kernel cryptography APIs, and for Linux on z Systems the libica cryptographic functions library. Cryptographic keys must be protected by your application system, as required.

  • On z/OS, IBM offers the Integrated Cryptographic Service Facility (ICSF) component that ships with the base product. ICSF is the software on z/OS that provides access to the z Systems CEX5S cryptographic hardware feature through the use of callable services that comply with IBM's Common Cryptographic Architecture (CCA). ICSF together with the IBM Resource Access Control Facility (RACF®) licensed program provide cryptographic services using the CCA security API.

  • On Linux on IBM Z, IBM offers a CCA API for the CEX6S and an IBM Enterprise PKCS #11 (EP11) API to the user. The CCA API shipped with the CEX6S is an enhanced version of the CCA API shipped with the CEX5S, CEX4S, or CEX3.

Explore CCA
Explore EP11

Explore CCA / EP11 comparison


The IBM 4768 hardware provides significant performance improvements over its predecessors while enabling future growth. The secure module contains redundant IBM PowerPC 476 processors, custom symmetric key and hashing engines to perform AES, DES, TDES, SHA-1 and SHA- 2, MD5 and HMAC as well as public key cryptographic algorithm support for RSA and Elliptic Curve Cryptography. Other hardware support includes a secure real-time clock, hardware random number generator and a prime number generator. The secure module is protected by a tamper responding design that protects against a wide variety of attacks against the system.

Reliability, Availability, and Serviceability (RAS)

Hardware has also been designed to support the highest level of RAS requirements that enables the secure module to self-check at all times. This is achieved by running a pair of PowerPC processors in lock step and comparing the result from each cycle by cycle. Also all interfaces, registers, memory, cryptographic engines, and buses are protected at all times using parity, ECC (Error Correcting Codes), or CRC. Power on self-tests that are securely stored inside the secure module verify the hardware and firmware loaded on the module is secure and reliable at every power on. Then, the built-in RAS features check it continuously in real time.

Embedded Certificate

During the final manufacturing step, the coprocessor generates a unique public/private key pair which is stored in the device. The tamper detection circuitry is activated at this time and remains active throughout the useful life of the coprocessor, protecting this private key as well as other keys and sensitive data. The public key of the coprocessor is certified at the factory by an IBM private key and the certificate is retained in the coprocessor. Subsequently, the private key of the coprocessor is used to sign the coprocessor status responses which, in conjunction with a series of public key certificates, demonstrate that the coprocessor remains intact and is genuine.

Tamper Responding Design

The IBM 4768 HSM is validated by NIST to meet the FIPS 140-2 Level 4 requirements by protecting against attacks that include probe penetration or other intrusion into the secure module, side-channel attacks, power manipulation, and temperature manipulation. From the time of manufacture, the hardware is self-protecting by using tamper sensors to detect probing or drilling attempts. If the tamper sensors are triggered, the HSM destroys critical keys and certificates, and is rendered permanently inoperable. Note therefore that the HSM must be maintained at all times within the temperature, humidity, and barometric pressure ranges specified. Refer to the environmental requirements section below.

Technical Specifications

Physical characteristics
Card type Full-height, half-length PCIe card
PCI Local Bus Specification 2.2
PCIe specification 1.1
Voltage +3.3 VDC ± 10% 23.44 W max
Required 25 W min
System requirements

This section describes requirements for the system in which the CEX6S is installed.

Hardware The CEX6S can be installed in an IBM Z mainframe (currently, z14® only).
Environmental requirements

From the time of manufacture, the IBM CEX6S cryptographic card must be shipped, stored, and used within the following environmental specifications. Outside of these specifications, the CEX6S tamper sensors can be activated and render the CEX6S permanently inoperable.

Shipping: The card should be shipped in original IBM packaging (electrostatic discharge bag with desiccant and thermally insulated box with gel packs).
Temp -34°C to +60°C
Pressure min 550 mbar
Humidity 5% to 100% RH
Storage: The card should be stored in electrostatic discharge bag with desiccant.
Temp +1°C to +60°C
Humidity 5% to 80% RH
Pressure min 700 mbar
Operation: (ambient in system)
Temp +10°C to +35°C
Humidity 8% to 80% RH
Operating altitude (max) 10 000 ft equivalent to 700 mbar min