Kinetis CAU

The Kinetis Cryptographic Acceleration Unit (CAU) is a primitive accelerator presented as a memory-mapped peripheral.

The SEGGER encryption library has specialized hardware-assisted ciphering and hashing support.

The following cryptographic algorithms use the CAU:

• DES in ECB and CBC modes
• TDES in ECB and CBC modes with keying options 1, 2, and 3
• AES-128, AES-192, and AES-256 in ECB and CBC modes.
• MD5
• SHA-1
• SHA-256
• RNG

All other cipher modes (e.g. AES-GCM and AES-CCM) use hardware-assisted ciphering of individual blocks, with software taking care of the cipher mode.

Cipher	Mode	Software Performance	Hardware Performance	Speedup
AES-128-ECB	Encrypt	2.17 MB/s	8.20 MB/s	x3.8
AES-192-ECB	Encrypt	1.86 MB/s	6.87 MB/s	x3.7
AES-256-ECB	Encrypt	1.62 MB/s	6.09 MB/s	x3.8
AES-128-CBC	Encrypt	1.72 MB/s	7.91 MB/s	x4.6
AES-192-CBC	Encrypt	1.52 MB/s	6.56 MB/s	x4.3
AES-256-CBC	Encrypt	1.36 MB/s	5.85 MB/s	x4.3
AES-128-CBC	Decrypt	1.61 MB/s	6.67 MB/s	x4.2
AES-192-CBC	Decrypt	1.43 MB/s	5.77 MB/s	x4.0
AES-256-CBC	Decrypt	1.29 MB/s	5.08 MB/s	x3.9

Cipher	Mode	Software Performance	Hardware Performance	Speedup
DES-ECB	Encrypt	1.05 MB/s	11.74 MB/s	x11.2
DES-EDE2-ECB	Encrypt	0.36 MB/s	11.74 MB/s	x32.6
DES-EDE3-ECB	Encrypt	0.36 MB/s	11.74 MB/s	x32.6
DES-CBC	Encrypt	0.90 MB/s	11.84 MB/s	x13.1
DES-EDE2-CBC	Encrypt	0.34 MB/s	11.85 MB/s	x34.7
DES-EDE3-CBC	Encrypt	0.34 MB/s	11.85 MB/s	x34.7
DES-CBC	Decrypt	0.84 MB/s	9.48 MB/s	x11.3
DES-EDE2-CBC	Decrypt	0.33 MB/s	9.48 MB/s	x28.7
DES-EDE3-CBC	Decrypt	0.33 MB/s	9.48 MB/s	x28.7