HIFN(4)

💖 HIFN(4) — the hifn crypto accelerator, bestie edition 💖

okay so real talk, this page is hifn(4) from the kernel interfaces manual, and it's all about the Hifn 7751/7951/7811/7955/7956 crypto accelerator driver. she's a little vintage, she's a little deprecated, but she ATE back in the day. let's get into it 🫶

---

✨ NAME ✨

hifn — the Hifn 7751/7951/7811/7955/7956 crypto accelerator. that's the whole vibe: hardware that does your crypto math for you so your CPU can chill 💅

---

🌸 SYNOPSIS 🌸

so if you want this driver baked into the kernel (no cap, some people still do this), you drop these lines into your kernel configuration file:

device crypto
device cryptodev
device hifn

OR, if you're more of a "load it as a module at boot" girlie, put this line in loader.conf(5):

hifn_load="YES"

that's it. that's the whole synopsis. slay 💖

---

🎀 DEPRECATION NOTICE 🎀

okay bestie, I gotta be the one to tell you: the hifn driver is deprecated and is scheduled for removal in FreeBSD 16.0. so like… she's iconic but she's on her way out. enjoy her while she's here 😭

---

🦋 DESCRIPTION 🦋

the hifn driver supports a whole lineup of cards containing the Hifn 7751, 7951, 7811, 7955, and 7956 chipsets.

the hifn driver registers itself to accelerate AES (and that's 7955 and 7956 only, just so we're clear 👑), SHA1, and SHA1-HMAC operations for ipsec(4) and crypto(4).

and the plot twist? the Hifn 7951, 7811, 7955, and 7956 will also supply data to the kernel random(4) subsystem. they're giving multitasking main character energy fr fr 🌈

---

💜 HARDWARE 💜

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 a 128KB SRAM model, or a 2MB DRAM model.
• Hifn 7751 — the reference board with 512KB SRAM.
• PowerCrypt — comes with 512KB SRAM.
• XL-Crypt — the only board based on the 7811 (which is faster than the 7751 and has a random number generator ✨).
• NetSec 7751 — supports the most IPsec sessions, with 1MB SRAM. she's the social butterfly of the group 💅
• 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.

---

🔥 SEE ALSO 🔥

crypto(4), intro(4), ipsec(4), random(4), crypto(7), crypto(9)

go read those too, iykyk 🧚

---

⭐ HISTORY ⭐

the hifn device driver appeared in OpenBSD 2.7. then the hifn device driver was imported to FreeBSD 5.0. so she's got lore. she's been around. respect the elder 👑

---

⚠️ CAVEATS ⚠️

okay so this part matters, bestie, listen up:

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. and since we do not currently attempt to use any of these chips to do compression, the 9751-based cards are not useful. like at all. 💀

also, support for the 7955 and 7956 is incomplete — the asymmetric crypto facilities are to be added and the performance is suboptimal. so she's a work in progress, basically. we're rooting for her 😭

---

🍓 BUGS 🍓

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. yes, really, that's the whole bit 🙈

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. so like… not the most secure lock in the world, but it is what it is 💅

---

ngl this whole section is giving "we hacked the hardware and we're not sorry." iconic behavior.

---

and that's the page, babe! this one was brought to you by the Debian crew, dated October 31, 2025, and filed under HIFN(4) 💜 happy crypting, and remember — deprecated doesn't mean unloved 🫶✨