HIFN(4) MidnightBSD Kernel Interfaces Manual HIFN(4)


hifn — Hifn 7751/7951/7811/7955/7956 crypto accelerator


device hifn


The hifn driver supports various cards containing the Hifn 7751, 7951, 7811, 7955, and 7956 chipsets.

The hifn driver registers itself to accelerate DES, Triple-DES, AES (7955 and 7956 only), ARC4, MD5, MD5-HMAC, SHA1, and SHA1-HMAC operations for ipsec(4) and crypto(4).

The Hifn 7951, 7811, 7955, and 7956 will also supply data to the kernel random(4) subsystem.


The hifn driver supports various cards containing the Hifn 7751, 7951, 7811, 7955, and 7956 chipsets, such as:

Invertex AEON

No longer being made. Came as 128KB SRAM model, or 2MB DRAM model.

Hifn 7751

Reference board with 512KB SRAM.


See http://www.powercrypt.com/. Comes with 512KB SRAM.


See http://www.powercrypt.com/. Only board based on 7811 (which is faster than 7751 and has a random number generator).

NetSec 7751

See http://www.netsec.net/. Supports the most IPsec sessions, with 1MB SRAM.

Soekris Engineering vpn1201 and vpn1211

See http://www.soekris.com/. Contains a 7951 and supports symmetric and random number operations.

Soekris Engineering vpn1401 and vpn1411

See http://www.soekris.com/. Contains a 7955 and supports symmetric and random number operations.


crypt(3), crypto(4), intro(4), ipsec(4), random(4), crypto(9)


The Hifn 9751 shares the same PCI ID. This chip is basically a 7751, but with the cryptographic functions missing. Instead, the 9751 is only capable of doing compression. Since we do not currently attempt to use any of these chips to do compression, the 9751-based cards are not useful.

Support for the 7955 and 7956 is incomplete; the asymmetric crypto facilities are to be added and the performance is suboptimal.


The hifn device driver appeared in OpenBSD 2.7. The hifn device driver was imported to FreeBSD 5.0.


The 7751 chip starts out at initialization by only supporting compression. A proprietary algorithm, which has been reverse engineered, is required to unlock the cryptographic functionality of the chip. It is possible for vendors to make boards which have a lock ID not known to the driver, but all vendors currently just use the obvious ID which is 13 bytes of 0.

MidnightBSD 0.3 September 12, 2004 MidnightBSD 0.3