FIPS Module Specification

This is a draft document

Cryptographic Module Specification

A series of security libraries present an application program interface (API) to client and server applications utilizing NSS. The libraries are compiled and built for specific platforms (see Platform List) and tagged with a release identifier to be published on mozilla.org. The release compliant with FIPS 140-2 is NSS 3.11.5.

The cryptographic module is defined to be a subset of the functions within these libraries. The subset is below the top layer of functions normally called by application programs, but the subset may be called by application programs directly if they so choose. Functions that are being certified include Triple DES(KO 1,2,3 56/112/168), AES(128/192/256), SHS (SHA-1, SHA-256, SHA-384, SHA-512), HMAC, DSA (512-1024), and RSA (1024-8092).

Module Components

NSS is a software cryptographic implementation. No hardware or firmware components are included. All input to the module is via function arguments; all output is returned to the caller either as return codes or as updated memory objects pointed to by some of the arguments.

Cryptographic Module	Library Name
PKCS #11	libsoftokn3
FREEBL	libfreebl3* (one is selected at run time)

Note: Filename extensions depend upon the target operating environment. For some CPUs libfreebl3 is distributed in more than one variant. The optimal version is selected at run time.

The database code of the NSS module (Berkeley DB 1.85, in mozilla/dbm and mozilla/security/nss/lib/softoken/dbmshim.c) is excluded from the security requirements of FIPS 140-2.

Rationale: The security-related information stored in the databases is either encrypted (e.g., secret and private cryptographic keys) or digitally signed (e.g., certificates and CRLs). If the database code is malfunctioning or misused, the PKCS #5 password-based encryption of the secret and private cryptographic keys will ensure their confidentiality and detect data corruption or malicious changes, and the digital signatures on the public data (certificates and CRLs) will detect data corruption or malicious changes. Therefore, the malfunction or misuse of the database code cannot cause a compromise under any reasonable condition.

The NSS module depends on the following libraries outside the cryptographic boundary.

NSS Dependencies	Library Name
Netscape Portable Runtime (NSPR)	libnspr4
NSPR string functions	libplc4
NSPR hashtables and arena pools	libplds4

The NSS module is used by the following higher-level NSS libraries outside the cryptographic boundary.

Higher-level NSS API	Library Name
CRMF	libcrmf
S/MIME	libsmime3
Certificate Management	libnss3
SSL	libssl3
JAR	libjar
PKCS #5	libnss3
PKCS #12	libsmime3

The Cryptographic Boundary

The NSS module is a multiple-chip standalone cryptographic module. The physical boundary of the NSS module is the enclosure of the general purpose computer it runs on, including any hardware or software that inputs, processes, or outputs important security parameters that could lead to the compromise of sensitive information if not properly controlled.

NSS's PKCS #11 (Cryptoki) implementation forms the cryptographic module. The API itself is considered to define the logical cryptographic boundary, thus all implementation is considered below the boundary. Also included in this module is the FIPS PKCS #11 token. This is a Cryptoki token designed specifically for FIPS, and allows applications using NSS to operate in a strictly FIPS mode. The diagram below shows the relationship of the layers.

Approved Mode of Operation

In order to run the NSS module in the FIPS Approved mode, an attribute must be explicitly set on the module. This can be done programmatically with a call to SECMOD_DeleteInternalModule() (with the module to delete being the internal module):

    SECMODModule *internal;
    SECStatus rv;

    internal = SECMOD_GetInternalModule();
    if (!internal) {
        /* handle error */
    }
    rv = SECMOD_DeleteInternalModule(internal->commonName);
    if (rv != SECSuccess) {
        /* handle error */
    }

or by running the NSS module utility modutil. An example command line is below:

   modutil -fips true -dbdir directory

where directory is the directory that contains the NSS databases.

The setting is permanent for the NSS module and all subsequent invocations of NSS functions using that NSS database directory will be in FIPS mode. The module can be taken out of FIPS mode by substituting false for true in the command above. The state of the module can be checked with:

   modutil -chkfips true -dbdir directory

where directory is the directory that contains the NSS databases, or with a call to PK11_IsFIPS().

Design Specification

The design of the software components of the NSS module is specified in the following documents:

• Finite State Model and Description
• Introduction to NSS
• NSS API Guidelines
• The pk11wrap layer and the softoken
• Physical format of the certificate database

Security-Related Information

Security-related information whose disclosure or modification can compromise the security of the NSS module includes:

• secret and private cryptographic keys (both plaintext and encrypted)
• passwords
• audited events, audit data