This International Standard defines the structure and the data elements of Authentication Context forBiometrics (ACBio), which is used for checking the validity of the result of a biometric verification process executed at a remote site. This International Standard allows any ACBio instance to accompany any data item that is involved in any biometric process related to verification and enrolment. The specification of ACBio is applicable not only to single modal biometric verification but also to multimodal fusion.This International Standard specifies the cryptographic syntax of an ACBio instance. The cryptographic syntax of an ACBio instance is based on an