SB nº 145: Clarification on the Format of ICC Public Key Exponent (Spec Change)

Specification Bulletin No. 145 First Edition September 2014 Clarification on the Format of ICC Public Key Exponent This Specification Bulletin clarifies the format, specifically the length, of the ICC Public Key Exponent data element.

Applicability

This Specification Bulletin applies to:  EMV Common Payment Application Specification, Version 1.0 plus bulletins, December 2005 Related Documents  EMV Integrated Circuit Card Specifications for Payment Systems Version 4.3

Description

It has been noted that there is an inconsistency in the CPA Specification v1 plus bulletins in the definition of the ICC Public Key Exponent (tag '9F47'). In the data dictionary (Annex L), it is defined with a length of 1 to 3 bytes; however, in section 21.2, it is defined as 1 or 3 bytes. This bulletin removes the inconsistency between the two definitions and aligns the definition with EMV 4.3. 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 the EMV Common Payment Application Specification, Annex L, page L-57, update the entry for ICC Public Key Exponent to the following: ICC Public Key Exponent Tag: '9F47' Length: 1 to or 3 Format: b Exponent used with the ICC Public Key. © 1994-2014 EMVCo, LLC (“EMVCo”). All rights reserved. Any and all uses of the EMV Specifications (“Materials”) shall be permitted only pursuant to the terms and conditions of the license agreement between the user and EMVCo found at http://www.emvco.com/specifications.cfm.