CFB-MAC
Cipher Feedback Mode MAC uses a block cipher in CFB mode to generate message authentication codes. Standardized in ISO/IEC 9797-1:1999.
Properties
| Property |
Value |
| Category |
Message Authentication |
| Sub-category |
Block Cipher MAC |
| Security status |
🎓 Educational Only |
| Complexity |
Intermediate |
| Inventor |
ISO/IEC JTC 1/SC 27 |
| Year |
1999 |
| Origin |
🌐 International |
| Source |
algorithms/mac/cfbmac.js |
Parameters
| Parameter |
Supported values |
| MAC sizes |
4 bytes (32 bits) to 16 bytes (128 bits) |
Capabilities
Security
Status: 🎓 Educational Only
Known vulnerabilities
| Issue |
Description |
Mitigation |
| Length Extension |
— |
CFB-MAC is vulnerable to message length extension attacks. Use CMAC or HMAC for production. |
Documentation
References
Test vectors
2 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — BouncyCastle MacTest Vector 1 - DES CFB-MAC with IV
| Field |
Value |
key |
0123456789abcdef |
iv |
1234567890abcdef |
macSize |
4 |
input |
37363534333231204e6f77206973207468652074696d6520666f7220 |
expected |
cd647403 |
Vector 2 — BouncyCastle MacTest Vector 2 - DES CFB-MAC, block-aligned 8 byte message
| Field |
Value |
key |
0123456789abcdef |
iv |
1234567890abcdef |
macSize |
4 |
input |
3736353433323120 |
expected |
3af549c9 |
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