ANSI X9.65-2004 pdf download Triple Data Encryption Algorithm (TDEA), Implementation Standard
5 Mode of Operation
5.1 Modes of Operation List
The modes of operation for TDEA are extensions of the four modes of operation for DEA specified in ANSI X3.106. The TDEA modes of operation include:
• TDEA Electronic Codebook Mode (TECB);
• TDEA Cipher Block Chaining Mode (TCBC);
• TDEA Cipher Block Chaining Mode – Interleaved (TCBC-I);
• TDEA Cipher Feedback Mode (TCFB);
• TDEA Cipher Feedback Mode – Pipelined (TCFB-P);
• TDEA Output Feedback Mode (TOFB);
• TDEA Cipher Feedback Mode – Interleaved (TOFB-I).
5.1.1 Modes of Operation and Usage
Although this standard addresses all modes of operation in the X9.52 Standard, for ease of implementation and backward compatibility, the following modes are suggested:
• TDEA Electronic Codebook Mode (TECB);
• TDEA Cipher Block Chaining Mode (TCBC);
• TDEA Cipher Feedback Mode (TCFB);
• TDEA Output Feedback Mode (TOFB).
5.1.2 Mode and Usage Matrix
This matrix indicates the modes of operation and recommended use of each indicated mode of operation.
5.2 Basis for the Modes of Operation The TECB, TCBC, TCFB and TOFB modes are based upon the ECB, CBC, CFB and OFB modes, respectively, defined in ANSI X3.106 (Data Encryption Algorithm – Modes of Operation). The TCBC–I mode is based on the TCBC mode, the TCFB–P mode is based on the TCFB mode, and the TOFB–I mode is based on the TOFB mode. Possible reasons for using one of the interleave or pipeline modes (TCBC–I, TCFB–P, or TOFB– I) include:
1. Minimization of propagation delay whereby at least one of the communicating parties has the possibility of employing multiple concurrently operating DEA implementations (DEA “engines”).
2. Interoperability with an existing implementation using Interleave or pipeline mode.
The TECB, TCBC, TCFB and TCFB modes may be backward compatible with their respective single DEA modes, ECB, CBC, CFB, and OFB, respectively providing keying option 3 is utilized as discussed in Section 5.3. Interleave and pipeline modes (TCBC–I, TCFB–P, and TOFB–I) are not backward compatible with their respective single DEA modes (CBC, CFB, and OFB), nor are they compatible with their respective TDEA modes (TCBC, TCFB, and TOFB).