X9。124金融服务业的对称密钥加密格式保护加密是一套标准，由五部分组成，定义了格式保护加密（FPE）方法。本标准第1部分包括所有FPE技术通用的一组定义、FPE分组密码技术的安全模型，以及定义本文件中指定模式时使用的伪码语言的描述。第5部分定义了使用AES或Triple-DES分组密码执行FPE的要求，该FPE使用了一种名为FF3的基于格式保护的Feistel模式。1.FF3。1是基于Feistel的FFX系列格式保护加密方法的一部分。

X9.124 Symmetric Key Cryptography for the Financial Services Industry Format Preserving Encryption is a suite of standards consisting of five parts that defines format-preserving encryption (FPE) methods. Part 1 of this standard includes a set of definitions common to all FPE techniques, a security model for FPE block cipher techniques, and a description of the pseudocode language used in defining the mode specified in this document. Part 5 defines requirements for using the AES or Triple-DES block cipher to perform FPE using a format-preserving Feistel-based mode known as FF3.1. FF3.1 is part of the FFX family of Feistel-based format preserving encryption methods.