Symmetric Cryptographic Accelerator Hard IP User Guide

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ID 714305
Date 11/28/2025
Public
Document Table of Contents
Document Table of Contents x
1. Introduction 2. Interface Overview 3. Parameters 4. Designing with the IP 5. Block Description 6. Cryptographic IP Data Profiles 7. Configuration Registers 8. Design Example 9. Document Revision History for the Symmetric Cryptographic Accelerator Hard IP User Guide
1. Introduction x
1.1. Terminology 1.2. IP Overview 1.3. Release Information 1.4. Device Family Support 1.5. Resource Utilization
1.2. IP Overview x
1.2.1. IP Applications
2. Interface Overview x
2.1. Clock Signals 2.2. Reset Signals 2.3. AXI-ST Interface 2.4. AXI-Lite Interface
4. Designing with the IP x
4.1. Installing and Licensing IP Cores 4.2. Specifying the IP Parameters and Options 4.3. Generated File Structure 4.4. Symmetric Cryptographic Accelerator Hard IP Flow 4.5. Dynamically Disabling the SM4 Capability 4.6. Error Handling 4.7. Error Reporting 4.8. Resetting the IP 4.9. Channel Definition and Allocation 4.10. Byte Ordering 4.11. AXI-ST Single Packet Mode 4.12. AXI-ST Multiple Packet Mode
4.1. Installing and Licensing IP Cores x
4.1.1. IP Evaluation Mode
4.6. Error Handling x
4.6.1. Steps to Record and Report the Received Errors to the Soft Logic 4.6.2. Detected Error Handling 4.6.3. Key RAM ECC Error Handling
4.6.2. Detected Error Handling x
4.6.2.1. Recovering from a Recoverable Error 4.6.2.2. Recovering from an Internal Error
5. Block Description x
5.1. Reset Sequencer 5.2. AXI-ST Ready Latency 5.3. AXI Adapter 5.4. Integrity Check Value Comparison 5.5. GCM Padding and Depadding
5.3. AXI Adapter x
5.3.1. MAC Packing 5.3.2. Data Last Indicator 5.3.3. Stream and Channel ID Buffering 5.3.4. TKEEP and LAST_SEGMENT Signals Generation 5.3.5. MAC Dropping on Decryption
5.5. GCM Padding and Depadding x
5.5.1. GCM Padding 5.5.2. GCM Depadding
6. Cryptographic IP Data Profiles x
6.1. MAC Security Profile (MACsec) 6.2. IP Security Profile (IPsec) 6.3. Generic GCM Profile (GCM) 6.4. Generic XTS Profile (XTS)
6.1. MAC Security Profile (MACsec) x
6.1.1. MACsec Flow 6.1.2. AXI-ST Interface Using MAC Security (MACsec) Profile Pattern
6.2. IP Security Profile (IPsec) x
6.2.1. AXI-ST Interface Using IP Security (IPsec) Profile Pattern
6.3. Generic GCM Profile (GCM) x
6.3.1. AXI- ST Interface Using Generic GCM Profile Pattern
6.4. Generic XTS Profile (XTS) x
6.4.1. AXI-ST Interface Using Generic XTS Profile Pattern
8. Design Example x
8.1. Functional Description 8.2. Crypto VSIP Top Block Descriptions 8.3. Test Configurations 8.4. Software Requirements 8.5. Simulation Requirements 8.6. Steps to Generate the Design Example 8.7. Running Simulation Tests 8.8. Running Hardware Tests
8.2. Crypto VSIP Top Block Descriptions x
8.2.1. Clock and Reset 8.2.2. Host Interface
8.7. Running Simulation Tests x
8.7.1. Steps to Simulate the Design Example
8.8. Running Hardware Tests x
8.8.1. Supported Boards 8.8.2. Steps to Compile the Design Example for Hardware 8.8.3. Steps to Run the Design Example on Hardware
1. Introduction
2. Interface Overview
3. Parameters
4. Designing with the IP
5. Block Description
6. Cryptographic IP Data Profiles
7. Configuration Registers
8. Design Example
9. Document Revision History for the Symmetric Cryptographic Accelerator Hard IP User Guide

5.5. GCM Padding and Depadding

The Symmetric Cryptographic Accelerator Hard IP supports AAD/Bypass/Text data padding and depadding feature when using the Generic GCM profile. This feature allows the AAD and Bypass data sent by you in the Crypto ingress direction to be padded in non-16 byte alignment within the payload. In the Crypto egress direction, the AAD, Bypass, Text, and MAC from the Crypto ICA hard IP are aligned to 16 bytes. The GCM depadding logic unpacks these 16 byte-aligned fields in the Symmetric Cryptographic Accelerator Hard IP to non-16 byte alignment and then sends them to your application via the AXI-ST bus. You can turn on of off the padding at ingress or depadding at egress separately in the IP parameter editor. If you turn off a feature, the IP optimizes away all the padding or depadding logic.

Figure 14. GCM Padding and Depadding
Note:

The length in Bypass, AAD, or Text field is for the last segment without counting the possible leading segments of 16-byte data.

Note: The MAC(16B) in the egress interface can disappear for decryption packets if you turn on Drop the MAC on applicable profile decryption.

Section Content
GCM Padding
GCM Depadding

Level Two Title