The document discusses Linux cryptography including the kernel crypto API framework, userspace crypto libraries, hardware acceleration, and the relationship between kernel and userspace crypto. The kernel crypto API provides interfaces for crypto algorithms that are used by network protocols, filesystems, and drivers. Userspace applications use crypto libraries like OpenSSL which interface with the kernel crypto API. Hardware acceleration offloads crypto operations to dedicated crypto hardware via the kernel crypto API, AF_ALG sockets, or cryptodev devices.

1. LINUX CRYPTO
2016/04/11 – 0.2

2. Linux Crypto Solution
 Kernel
 Kernel CryptoAPI framework
 network protocols, filesystems, and drivers use kernel crypto APIs
 Userspace
 crypto library like OpenSSL
 applications use crypto APIs provided by crypto library
 Kernel vs Userspace
 kernel crypto API and userspace crypto library are two
independent modules without any relationship
 Hardware Acceleration/Offload
 Hardware implementation of crypto algorithms for kernel Crypto
API
 Userspace application acceleration via AF_ALG socket, cryptodev
device, etc.. kernel-userpace interface

3. Kernel Crypto API Framework
Kernel Crypto API Framework
Kernel Interface (crypto/...)
Transform Interface Transform Helper Algorithm API Wrappers
Core Logic (/crypto/...)
Generic Transform Logic
Cipher Logic
ECB, CBC, CFB, CTR modes
Digest Logic
HMAC
Compression Logic
Page Vector (scatter list) Logic
Algorithm Management (/crypto/...)
Dynamic Algorithm Loader
Algorithm Register Interface
crypto_register_alg(), crypto_unregister_alg()
Algorithm Implementations
SW Algorithms (/crypto/...)
[etc.]DES, 3DES AES MD5 SHA1
HW drivers
(driver/crypto/...)
Kernel/User Interface (crypto/...)
AF_ALG socket
aead skcipher hash rng

4. Linux Crypto Hardware
Acceleration/Offload
Kernel Crypto API Core
OpenSSL Library (, ... etc)
AF_ALG
Cryptodev-linux
HW Crypto Driver
AF_ALG plugin
cryptodev
plugin
HW Crypto Engine
SOCKET IOCTL
(/dev/crypto)
Proprietary
user space
kernel space
Other Kernel
components
Applications
SW Algorithms
HW

5. Reference
 Linux Kernel Crypto API
 https://www.kernel.org/doc/htmldocs/crypto-
API/index.html
 libkcapi - Linux Kernel Crypto API User Space
Interface Library
 http://www.chronox.de/libkcapi.html
 Cryptodev-linux
 http://cryptodev-linux.org/
 Utilizing the crypto accelerators
 http://events.linuxfoundation.org/sites/events/files/sli
des/lcj-2014-crypto-user.pdf