What does FIPS 140 mode mean for users of z/OS Communications Server ?

Federal Information Processing Standards (FIPS) document 140 (FIPS 140) provides a higher degree of assurance of the integrity of cryptographic operations by placing restrictions on the cryptographic components and the operations performed by these components. Weaker algorithms are forbidden and all the operations must be performed by cryptographic modules that are contained within a well defined cryptographic boundary.

You can configure the IKED, the NSSD, and the TCP/IP stack components to operate in FIPS 140 mode. When you do, you restrict the cryptographic algorithms they support, and you modify their interactions with each other and with the other hardware and software components of the z/OS system related to cryptography, such as Integrated Cryptographic Services Facility (ICSF) and System SSL.

In FIPS 140 mode, the IKED, the NSSD, and the TCP/IP stacks enforce the following restrictions on the cryptographic algorithms that can be used for IP security:

• You cannot use the DES encryption algorithm.

• You cannot use the HMAC-MD5, HMAC-MD5-96, AES128-XCBC, and AES128-XCBC-96 algorithms for authentication or pseudo-random function.

• You cannot use Diffie-Hellman groups 1, 2, and 5.

• You cannot use certificates for RSA signature authentication that have key lengths less than 1024 bits.

• You cannot use pre-shared keys whose length is less than half the key size of the chosen HowToAuthMsgs (IKEv1) or PseudoRandomFunction (IKEv2) algorithm

You should be aware that there are possible negative performance impacts from implementing FIPS 140. For more information, see "What are the possible impacts of FIPS 140 mode on z/OS Communications Server performance?"