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X9: Accredited Standards Committee X9, Inc.

ASC X9, the Accredited Standards Committee X9, is a nonprofit organization that develops and publishes standards for the financial services industry. Headquartered in Annapolis, United States, ASC X9 standards define the workings of the financial industry in the United States. With approximately 130 member companies, including key industry leaders, and the global financial influence wielded by the United States, ASC X9 standards strongly affect financial systems throughout the world. ASC X9 also serves as the administrator for the U.S. TAGs (United States Technical Advisory Group) to ISO/TC 68 (International Organization for Standardization/Technical Committee) and to three of its subcommittees. Standards from X9 are available both individually, directly through the ANSI webstore, and as part of a Standards Subscription. If you or your organization are interested in easy, managed, online access to standards that can be shared, a Standards Subscription may be what you need - please contact us at: or 1-212-642-4980 or Request Proposal Price.

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ASC X9 TR 31-2018

Interoperable Secure Key Exchange Key Block Specification.

TR 31 describes a method consistent with the requirements of ANS X9.24 Retail Financial Services Symmetric Key Management Part 1 for the secure exchange of keys and other sensitive data between two devices that share a symmetric key exchange key. This method may also be used for the storage of keys under asymmetric key. This document is not a security standard and is not intended to establish security requirements. It is intended instead to provide an interoperable method of implementing security requirements and policies.

ANSI X9.138-2020

Distributed Ledger Technologies (DLT) Terminology

This standard defines terminology for blockchain, digital currency, and distributed ledger technologies (DLT) for use in the financial services industry. These defined terms are intended to assist regulators, inform future legislation, and provide consistency in the development of future X9 financial services standards. A standardized vocabulary will help remove barriers to the adoption of new technologies that can improve operating efficiency in financial services, reduce cost for banks and their customers, and lead to greater understanding in our legal and regulatory community. The scope of this standard includes terms used to describe blockchain, digital currency, and DLT. These include terms related to business, legal, legislation, and technology.

ANSI/X9 TR-39-2009

TG-3 Retail Financial Services Compliance Guideline - Part 1: PIN Security and Key Management

This guideline applies to all organizations using the Triple Data Encryption Algorithm - TDEA (Reference 7) for the encryption of PINs used for retail financial services such as POS and ATM transactions, messages among retailers and financial institutions, and interchange messages among acquirers, switches and card issuers. The guideline should be completed by all organizations acquiring or processing transactions containing PINs, from the terminal driving system to the authorizing entity. The guideline Control Objectives address security controls from the PIN entry device to the interface delivering the transaction to the authorizing entity. When this guideline is completed by a device manufacturer, the Control Objectives are intended to evaluate the manufacturing environment and the device's ability to be implemented in a manner compliant with X9.8 and X9.24 (all parts). 

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ANSI X9.100-188-2018

Financial Services - Return Reasons for Check - Image Exchange and IRDs

This standard lists the Return Reason codes for both Customer and Administrative Returns for image exchange and IRD creation within the U.S. Payments System. It includes the Short Name and Overlay Abbreviation required for an IRD creation. The standard establishes the process to add, change or delete a Return Reason code. It is up to each individual financial institution to determine what Return Reason code they will use when returning a check. The standard also includes guidance for the proper use of Return Reason codes.

ASC X9 TR 34-2019

Interoperable Method for Distribution of Symmetric Keys Using Asymmetric Techniques: Part 1 - Using Factoring-Based Public Key Cryptography Unilateral Key Transport - Includes Corrigendum

TR-34 describes a method consistent with the requirements of ANS X9.24 - 2 Retail Financial Services Symmetric Key Management - Part 2: Using Asymmetric Techniques for the Distribution of Symmetric Keys for the secure exchange of keys using asymmetric techniques between two devices that share asymmetric keys. This method is designed to operate within the existing capabilities of devices used in the retail financial services industry. Includes Corrigendum.

ASC X9 TR 51-2020

Levies Companion Document Uniform Adoption of X9.129 for Levies Version 3.0

The purpose of this document is to formalize an industry standard for exchange of legal orders using the ANSI X9.129 standard format and a compilation of industry norms. This document is not intended to replace the ANSI X9.129 standard, but rather to clarify how financial institutions and agencies should use the standard to ensure all necessary and appropriate levies and asset based orders are exchanged between financial institutions and/or agencies. The use of this document requires that all legal orders exchange participants obtain, use and adhere to the record and field usage definitions detailed in the ANSI X9.129 standard. Users of this document are required to review and be knowledgeable of the full standard to ensure file structure and data and field specifications are understood and used correctly. This document further defines the specific usage of the ANSI X9.129 standard and describes all of the records and fields which contain critical data. Based on this usage, it is reasonable to expect that exchange participants will implement file validation practices to ensure that all critical data is contained in legal order exchange files. If a file contains records or fields of critical data that do not conform to the usage practices detailed in the standard it is reasonable to expect the receiving institution or agency will reject the item or file back to the sending institution or agency as the order(s) contained in the file may be unusable/unprocessable. Conversely, if a record or field which does not contain critical data is populated with incomplete, erroneous, or invalid data it is reasonable to expect these files or items would be accepted and processed.

ANSI X9.24-3-2017

Retail Financial Services Symmetric Key Management - Part 3: Derived Unique Key Per Transaction

This part of the standard describes the AES DUKPT algorithm (Derived Unique Key Per Transaction), which uses a Base Derivation Key (BDK) to derive unique per device initial keys for transaction originating SCDs, and derive unique per transaction working keys from the initial keys based on the transaction number. Working keys can be used for a variety of functions, such as encryption of PINs, data or other keys, for derivation of other keys, for message authentication, etc. AES DUKPT supports the derivation of AES-128, AES-192, AES-256, and double and triple length TDEA keys from AES-128, AES-192, and AES-256 BDKs

ANSI X9.100-187-2016

Electronic Exchange of Check and Image Data

Since the enactment of Check 21, there has been unprecedented adoption of image exchange. This standard establishes the basis for U.S. check image exchange between financial institutions; all financial values in this standard are assumed to represent U.S. Dollars. This standard establishes requirements and limitations that are compatible with current industry practice. It maintains flexibility in order to accommodate the needs of different institutions and exchange networks. Users of this standard should be aware that most financial exchanges utilize a ôcompanion documentö that defines the specific requirements and implementation rules for exchange within a particular network or institution agreement. The companion document should reference the specific edition of this standard that applies with the specific version of the companion document in use. Generally, US check exchange utilizes the Universal Companion Document (UCD) that can be referenced at the CheckImage Collaborative website, CheckImage Central at This standard, including the normative annexes, establishes the file sequences, record types, and field formats to be used for the electronic exchange of check MICR line, associated check processing data and check images in the form of cash letters. This standard does not address operational, implementation, or settlement needs. These requirements may include, but are not limited to, a choice of: data and image compression, encryption, and transmission specifications and data representation. The informative annexes attached to this standard provide information that may prove useful to those planning to implement the standard.


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