SB nº 147: Clarification on the Format of Exponent Data Elements (Spec Change)

Specification Bulletin No. 147 First Edition September 2014 Clarification on the Format of Exponent Data Elements This Specification Bulletin clarifies the format, specifically the length, of the public key exponent data elements.

Applicability

This Specification Bulletin applies to:  EMV Integrated Circuit Card Specifications for Payment Systems Version 4.3 Book 3 Related Documents  EMV Integrated Circuit Card Specifications for Payment Systems Version 4.3 Book 2

Description

It has been noted that there is an inconsistency between EMV Book 2 and Book 3 in the description of the length of the public key exponents, i.e. the Issuer Public Key Exponent (tag '9F32') and the ICC Public Key Exponent (tag '9F47'). This bulletin removes the inconsistency between Book 2 and Book 3 by updating the data element descriptions in Book 3. Note: The updated description of the public key exponent length, "1 or 3", technically allows for e=3 to be coded on 3 bytes. However, it is recommended that issuers code e=3 on 1 byte (and e=216+1 on 3 bytes).

Specification Change In EMV Book 3, Annex A, Table 33, update the following data element entries as shown: Name Integrated Circuit Card (ICC) Public Key Exponent Issuer Public Key Exponent Description ICC Public Key Exponent used for the verification of the Signed Dynamic Application Data Issuer public key exponent used for the verification of the Signed Static Application Data and the ICC Public Key Certificate Source ICC ICC Format b Template '70' or '77' Tag '9F47' Length 1 to or 3 b '70' or '77' '9F32' 1 to or 3