The Common Criteria for Information Technology Security Evaluation, or simply Common Criteria (CC), is an information security standard. It is adopted in ISO/IEC 15408:2022.
Common Criteria is a framework in which computer system users can specify their security functional and assurance requirements (SFRs and SARs, respectively) in a Security Target (ST), and may be taken from Protection Profiles (PPs). Vendors can then implement or make claims about the security attributes of their products, and testing laboratories can evaluate the products to determine if they actually meet the claims. In other words, Common Criteria provides assurance that the process of specification, implementation and evaluation of a computer security product has been conducted in a rigorous and standard and repeatable manner at a level that is commensurate with the target environment for use. Common Criteria maintains a list of certified products, including operating systems, access control systems, databases, and key management systems.
Characteristics Common Criteria evaluations are performed on computer security products and systems.
Target of Evaluation (TOE) the product or system that is the subject of the evaluation. The evaluation serves to validate claims made about the target. Protection Profile (PP) a document, typically created by a user or user community, which identifies security requirements for a class of security devices (for example, smart cards used to provide digital signatures, or network firewalls) relevant to that user for a particular purpose. Product vendors can choose to implement products that comply with one or more PPs, and have their products evaluated against those PPs. In such a case, a PP may serve as a template for the product's ST (Security Target, as defined below), or the authors of the ST will at least ensure that all requirements in relevant PPs also appear in the target's ST document. Customers looking for particular types of products can focus on those certified against the PP that meets their requirements. Security Target (ST) the document that identifies the security properties of the target of evaluation. The ST may claim conformance with one or more PPs. The TOE is evaluated against the SFRs (Security Functional Requirements. Again, see below) established in its ST, no more and no less. This allows vendors to tailor the evaluation to accurately match the intended capabilities of their product. This means that a network firewall does not have to meet the same functional requirements as a database management system, and that different firewalls may in fact be evaluated against completely different lists of requirements. The ST is usually published so that potential customers may determine the specific security features that have been certified by the evaluation. Security Functional Requirements (SFRs) specify individual security functions which may be provided by a product. The Common Criteria presents a standard catalogue of such functions. For example, a SFR may state how a user acting a particular role might be authenticated. The list of SFRs can vary from one evaluation to the next, even if two targets are the same type of product. Although Common Criteria does not prescribe any SFRs to be included in an ST, it identifies dependencies where the correct operation of one function (such as the ability to limit access according to roles) is dependent on another (such as the ability to identify individual roles). Security Assurance Requirements (SARs) descriptions of the measures taken during development and evaluation of the product to assure compliance with the claimed security functionality. For example, an evaluation may require that all source code is kept in a change management system, or that full functional testing is performed. The Common Criteria provides a catalogue of these, and the requirements may vary from one evaluation to the next. The requirements for particular targets or types of products are documented in the ST and PP, respectively. Evaluation Assurance Level (EAL) the numerical rating describing the depth and rigor of an evaluation. Each EAL corresponds to a package of security assurance requirements (SARs, see above) which covers the complete development of a product, with a given level of strictness. Common Criteria lists seven levels, with EAL 1 being the most basic (and therefore cheapest to implement and evaluate) and EAL 7 being the most stringent (and most expensive). Normally, an ST or PP author will not select assurance requirements individually but choose one of these packages, possibly 'augmenting' requirements in a few areas with requirements from a higher level. Higher EALs do not necessarily imply "better security", they only mean that the claimed security assurance of the TOE has been more extensively verified.
So far, most PPs and most evaluated STs/certified products have been for IT components (e.g., firewalls, operating systems, smart cards).
Common Criteria certification is sometimes specified for IT procurement. Other standards containing, e.g., interoperation, system management, user training, supplement CC and other product standards. Examples include the ISO/IEC 27002 and the German IT baseline protection.
Details of cryptographic implementation within the TOE are outside the scope of the CC. Instead, national standards, like FIPS 140-2, give the specifications for cryptographic modules, and various standards specify the cryptographic algorithms in use.
More recently, PP authors are including cryptographic requirements for CC evaluations that would typically be covered by FIPS 140-2 evaluations, broadening the bounds of the CC through scheme-specific interpretations.
Some national evaluation schemes are phasing out EAL-based evaluations and only accept products for evaluation that claim strict conformance with an approved PP. The United States currently only allows PP-based evaluations.
History CC originated out of three standards:
ITSEC – The European standard, developed in the early 1990s by France, Germany, the Netherlands and the UK. It too was a unification of earlier work, such as the two UK approaches (the CESG UK Evaluation Scheme aimed at the defence/intelligence market and the DTI Green Book aimed at commercial use), and was adopted by some other countries, e.g. Australia. CTCPEC – The Canadian standard followed from the US DoD standard, but avoided several problems and was used jointly by evaluators from both the U.S. and Canada. The CTCPEC standard was first published in May 1993. TCSEC – The United States Department of Defense DoD 5200.28 Std, called the Orange Book and parts of the Rainbow Series. The Orange Book originated from Computer Security work including the Anderson Report, done by the National Security Agency and the National Bureau of Standards (the NBS eventually became NIST) in the late 1970s and early 1980s. The central thesis of the Orange Book follows from the work done by Dave Bell and Len LaPadula for a set of protection mechanisms.
CC was produced by unifying these pre-existing standards, predominantly so that companies selling computer products for the government market (mainly for Defence or Intelligence use) would only need to have them evaluated against one set of standards. The CC was developed by the governments of Canada, France, Germany, the Netherlands, the UK, and the U.S.
Testing organizations All testing laboratories must comply with ISO/IEC 17025, and certification bodies will normally be approved against ISO/IEC 17065.
The compliance with ISO/IEC 17025 is typically demonstrated to a National approval authority: In Canada, the Standards Council of Canada (SCC) under Program for the Accreditation of Laboratories (PALCAN) accredits Common Criteria Evaluation Facilities (CCEF) In France, the (COFRAC) accredits Common Criteria evaluation facilities, commonly called (CESTI). Evaluations are done according to norms and standards specified by the Agence nationale de la sécurité des systèmes d'information (ANSSI). In Italy, the OCSI (Organismo di Certificazione della Sicurezza Informatica) accredits Common Criteria evaluation laboratories In India, the STQC Directorate of the Ministry of Electronics and Information Technology evaluates and certifies IT products at assurance levels EAL 1 through EAL 4. In the UK the United Kingdom Accreditation Service (UKAS) used to accredit Commercial Evaluation Facilities (CLEF) ; the UK is since 2019 only a consumer in the CC ecosystem In the US, the National Institute of Standards and Technology (NIST) National Voluntary Laboratory Accreditation Program (NVLAP) accredits Common Criteria Testing Laboratories (CCTL) In Germany, the Bundesamt für Sicherheit in der Informationstechnik (BSI) In Spain, the National Cryptologic Center (CCN) accredits Common Criteria Testing Laboratories operating in the Spanish Scheme. In The Netherlands, the Netherlands scheme for Certification in the Area of IT Security (NSCIB) accredits IT Security Evaluation Facilities (ITSEF). In Sweden, the Swedish Certification Body for IT Security (CSEC) licenses IT Security Evaluation Facilities (ITSEF).
Characteristics of these organizations were examined and presented at ICCC 10.
Mutual recognition arrangement As well as the Common Criteria standard, there is also a sub-treaty level Common Criteria MRA (Mutual Recognition Arrangement), whereby each party thereto recognizes evaluations against the Common Criteria standard done by other parties. Originally signed in 1998 by Canada, France, Germany, the United Kingdom and the United States, Australia and New Zealand joined 1999, followed by Finland, Greece, Israel, Italy, the Netherlands, Norway and Spain in 2000. The Arrangement has since been renamed Common Criteria Recognition Arrangement (CCRA) and membership continues to expand. Within the CCRA only evaluations up to EAL 2 are mutually recognized (Including augmentation with flaw remediation). The European countries within the SOGIS-MRA typically recognize higher EALs as well. Evaluations at EAL5 and above tend to involve the security requirements of the host nation's government.
In September 2012, a majority of members of the CCRA produced a vision statement whereby mutual recognition of CC evaluated products will be lowered to EAL 2 (Including augmentation with flaw remediation). Further, this vision indicates a move away from assurance levels altogether and evaluations will be confined to conformance with Protection Profiles that have no stated assurance level. This will be achieved through technical working groups developing worldwide PPs, and as yet a transition period has not been fully determined.
On July 2, 2014, a new CCRA was ratified per the goals outlined within the 2012 vision statement. Major changes to the Arrangement include: Recognition of evaluations against only a collaborative Protection Profile (cPP) or Evaluation Assurance Levels 1 through 2 and ALC_FLR. The emergence of international Technical Communities (iTC), groups of technical experts charged with the creation of cPPs. A transition plan from the previous CCRA, including recognition of certificates issued under the previous version of the Arrangement.
Issues
Requirements
Common Criteria is a very generic standard; it does not directly provide a list of product security requirements or features for specific (classes of) products: this follows the approach taken by ITSEC, but has been a source of debate to those used to the more prescriptive approach of other earlier standards such as TCSEC and FIPS 140-2.
Value of certification