ISO/IEC 19785-4:2010

INTERNATIONAL ISO/IEC
STANDARD 19785-4
First edition
2010-08-15
Information technology — Common
Biometric Exchange Formats
Framework —
Part 4:
Security block format specifications
Technologies de l'information — Cadre de formats d'échange
biométriques communs —
Partie 4: Spécifications de format de bloc de sécurité

Reference number
©
ISO/IEC 2010
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©  ISO/IEC 2010
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ii © ISO/IEC 2010 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
3.1 Terms defined in ISO/IEC 19785-1 .2
3.2 Terms defined in ISO/IEC 19784-1 .2
3.3 Terms defined in ISO/IEC 24761 .2
3.4 Terms defined in ISO/IEC 9798-6 .2
4 Abbreviated terms .2
4.1 Abbreviated terms defined in ISO/IEC 19785-1 .2
4.2 Abbreviated terms defined in ISO/IEC 24761.2
4.3 Abbreviated terms defined in ISO/IEC 9798-6 .2
4.4 Abbreviated terms defined in RFC 3852 .3
5 Security block format: general purpose .3
5.1 Security block format owner .3
5.2 Security block format owner identifier.3
5.3 Security block format name .3
5.4 Security block format identifier .3
5.5 ASN.1 object identifier for this security block format .3
5.6 Domain of use.4
5.7 Version identifier .4
5.8 Format specification and conformance statement .4
5.9 Encoding of abstract values .10
6 Security block format: signature only.11
6.1 Security block format owner .11
6.2 Security block format owner identifier.11
6.3 Security block format name .11
6.4 Security block format identifier .11
6.5 ASN.1 object identifier for this security block format .11
6.6 Domain of use.12
6.7 Version identifier .12
6.8 Format specification and conformance statement .12
Annex A (normative) ASN.1 module for security block format.13
Annex B (informative) Difference from types defined in RFC 5911 .15
Bibliography.18

© ISO/IEC 2010 – All rights reserved iii

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 19785-4 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 37, Biometrics.
ISO/IEC 19785 consists of the following parts, under the general title Information technology — Common
Biometric Exchange Formats Framework:
⎯ Part 1: Data element specification
⎯ Part 2: Procedures for the operation of the Biometric Registration Authority
⎯ Part 3: Patron format specifications
⎯ Part 4: Security block format specifications
iv © ISO/IEC 2010 – All rights reserved

Introduction
Biometric verification and identification are important techniques for the authentication and/or identification of
an individual. Biometric data used in biometric verification and identification has to be from a trusted source
with no interference in transmission (integrity). It might or might not be necessary for it to be kept secret
(encryption) depending on security policy. This part of ISO/IEC 19785 provides for both integrity and
encryption of the biometric data.
To ensure interoperability, the Common Biometric Exchange Formats Framework (CBEFF) was specified in
ISO/IEC 19785-1 to associate meta-data with one or more Biometric Data Blocks (BDBs). In ISO/IEC 19785-1,
the options for integrity and encryption, and the concept of a security block (SB) to contain security information
related to these options are defined, but the format and detailed content of security blocks (SB formats) are
not specified.
There are several steps in the chain, starting from a CBEFF patron format.
First, the patron format can determine that the abstract value of the CBEFF data element
CBEFF_BDB_encryption_options is fixed as NO ENCRYPTION and that the CBEFF data element
CBEFF_BIR_integrity_options is fixed as NO INTEGRITY. In this case, there is no need for a security block to
be required in that patron format.
If the patron format requires the inclusion of a security block in some circumstances, it can fix it as one of the
security blocks defined in this part of ISO/IEC 19785 (or as some other security block), or can include the
CBEFF data elements CBEFF_SB_format_owner and CBEFF_SB_format_type to identify one of these or
some other security block format.
Besides the security block formats defined in this part of ISO/IEC 19785, there will be many possible CBEFF
security block formats meeting different needs. For example, a security block format is specified for the ILO
seafarers profile in ISO/IEC 24713-3. The security block format specified in Clause 5 is designed to be as
general as possible. The security block format specified in Clause 6 is designed to provide a basic security
provision and supports integrity only.
This part of ISO/IEC 19785 specifies two security block formats.
The first security block specifies a general-purpose security block format with optional elements for encryption,
and for integrity, using RFC 3852 Cryptographic Message Syntax (CMS), with certain modifications to
EnvelopedData, EncryptedData, SignedData, and AuthenticatedData, to meet the needs and requirements
in expressing the security of biometric information in conformance with CBEFF. The second is named
signature-only security block format, which is also defined using RFC 3852.
The general-purpose security block format specified in this part of ISO/IEC 19785 also contains optional
Authentication Context for Biometrics (ACBio) instances specified in ISO/IEC 24761. ACBio also uses the
RFC 3852 Cryptographic Message Syntax scheme. The inclusion of ACBio instances enables the security
levels of the systems producing the authenticated biometric to be determined. The optional use of ACBio
instances is an important part of the provision of a telebiometric authentication infrastructure (TAI) [3].
© ISO/IEC 2010 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 19785-4:2010(E)

Information technology — Common Biometric Exchange
Formats Framework —
Part 4:
Security block format specifications
1 Scope
This part of ISO/IEC 19785 specifies security block formats (see ISO/IEC 19785-1) registered in accordance
with ISO/IEC 19785-2 as formats defined by the CBEFF biometric organization ISO/IEC JTC 1/SC 37, and
specifies their registered security block format identifiers.
NOTE The security block format identifier is recorded in the standard biometric header (SBH) of a patron format (or
defined by that patron format as the only available security block format).
The general-purpose security block format provides for specification of whether the biometric data block
(BDB) is encrypted or the SBH and BDB have integrity applied (or both), and can include ACBio instances
(see ISO/IEC 24761). This security block provides all necessary security parameters, including those used for
encryption or integrity.
It does not restrict the algorithms and parameters used for encryption or integrity, but provides for the
recording of such algorithms and parameter values.
It is a matter for profiling to determine, for a particular application area, what algorithms and parameter ranges
can be used by the generator of a security block, and hence what algorithms and parameter ranges have to
be supported by the user of a security block. This is out of the scope of this part of ISO/IEC 19785.
The second security block is more limited, but simpler (and in particular cannot contain ACBio instances, and
does not support encryption of the BDB).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 8824 (all parts) | ITU-T Rec. X.680–683, Information technology — Abstract Syntax Notation One
(ASN.1)
ISO/IEC 8825 (all parts) | ITU-T Rec. X.690–693, Information technology — ASN.1 encoding rules
ISO/IEC 9798-6, Information technology — Security techniques — Entity authentication —
Part 6: Mechanisms using manual
...