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CRYPTO(9) Kernel Developer's Manual CRYPTO(9)

crypto — API for cryptographic services in the kernel

#include <opencrypto/cryptodev.h>

crypto is a framework for in-kernel cryptography. It permits in-kernel consumers to encrypt and decrypt data and also enables userland applications to use cryptographic hardware through the /dev/crypto device.

crypto supports encryption and decryption operations using block and stream ciphers as well as computation and verification of message authentication codes (MACs). Consumers allocate sessions to describe a transform as discussed in crypto_session(9). Consumers then allocate request objects to describe each transformation such as encrypting a network packet or decrypting a disk sector. Requests are described in crypto_request(9).

Device drivers are responsible for processing requests submitted by consumers. crypto_driver(9) describes the interfaces drivers use to register with the framework, helper routines the framework provides to facilitate request processing, and the interfaces drivers are required to provide.

Since the consumers may not be associated with a process, drivers may not sleep(9). The same holds for the framework. Thus, a callback mechanism is used to notify a consumer that a request has been completed (the callback is specified by the consumer on a per-request basis). The callback is invoked by the framework whether the request was successfully completed or not. Errors are reported to the callback function.

Session initialization does not use callbacks and returns errors synchronously.

Operations may fail with a specific error code, EAGAIN, to indicate that a session handle has changed and that the request may be re-submitted immediately with the new session. The consumer should update its saved copy of the session handle to the value of crp_session so that future requests use the new session.

More details on some algorithms may be found in crypto(7).

The following authentication algorithms are supported:

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The following encryption algorithms are supported:

 
 
 
 
 
 

The following authenticated encryption with additional data (AEAD) algorithms are supported:

 
 
 

The following compression algorithms are supported:

 

sys/opencrypto/crypto.c
most of the framework code

crypto(4), ipsec(4), crypto(7), crypto_driver(9), crypto_request(9), crypto_session(9), sleep(9)

The cryptographic framework first appeared in OpenBSD 2.7 and was written by Angelos D. Keromytis <angelos@openbsd.org>.

The framework needs a mechanism for determining which driver is best for a specific set of algorithms associated with a session. Some type of benchmarking is in order here.

April 12, 2021 dev