Crypto

Overview

API Reference

group crypto_cipher

Crypto Cipher APIs.

Defines

CAP_OPAQUE_KEY_HNDL
CAP_RAW_KEY
CAP_KEY_LOADING_API
CAP_INPLACE_OPS

Whether the output is placed in separate buffer or not

CAP_SEPARATE_IO_BUFS
CAP_SYNC_OPS

These denotes if the output (completion of a cipher_xxx_op) is conveyed by the op function returning, or it is conveyed by an async notification

CAP_ASYNC_OPS
CAP_AUTONONCE

Whether the hardware/driver supports autononce feature

CAP_NO_IV_PREFIX

Don’t prefix IV to cipher blocks

Typedefs

typedef int (*block_op_t)(struct cipher_ctx *ctx, struct cipher_pkt *pkt)
typedef int (*cbc_op_t)(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *iv)
typedef int (*ctr_op_t)(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *ctr)
typedef int (*ccm_op_t)(struct cipher_ctx *ctx, struct cipher_aead_pkt *pkt, uint8_t *nonce)
typedef int (*gcm_op_t)(struct cipher_ctx *ctx, struct cipher_aead_pkt *pkt, uint8_t *nonce)
typedef void (*crypto_completion_cb)(struct cipher_pkt *completed, int status)

Enums

enum cipher_algo

Cipher Algorithm

Values:

enumerator CRYPTO_CIPHER_ALGO_AES
enum cipher_op

Cipher Operation

Values:

enumerator CRYPTO_CIPHER_OP_DECRYPT
enumerator CRYPTO_CIPHER_OP_ENCRYPT
enum cipher_mode

Possible cipher mode options.

More to be added as required.

Values:

enumerator CRYPTO_CIPHER_MODE_ECB
enumerator CRYPTO_CIPHER_MODE_CBC
enumerator CRYPTO_CIPHER_MODE_CTR
enumerator CRYPTO_CIPHER_MODE_CCM
enumerator CRYPTO_CIPHER_MODE_GCM

Functions

int cipher_query_hwcaps(const struct device *dev)

Query the crypto hardware capabilities.

This API is used by the app to query the capabilities supported by the crypto device. Based on this the app can specify a subset of the supported options to be honored for a session during cipher_begin_session().

Return

bitmask of supported options.

Parameters

  • dev: Pointer to the device structure for the driver instance.

int cipher_begin_session(const struct device *dev, struct cipher_ctx *ctx, enum cipher_algo algo, enum cipher_mode mode, enum cipher_op optype)

Setup a crypto session.

Initializes one time parameters, like the session key, algorithm and cipher mode which may remain constant for all operations in the session. The state may be cached in hardware and/or driver data state variables.

Return

0 on success, negative errno code on fail.

Parameters

  • dev: Pointer to the device structure for the driver instance.

  • ctx: Pointer to the context structure. Various one time parameters like key, keylength, etc. are supplied via this structure. The structure documentation specifies which fields are to be populated by the app before making this call.

  • algo: The crypto algorithm to be used in this session. e.g AES

  • mode: The cipher mode to be used in this session. e.g CBC, CTR

  • optype: Whether we should encrypt or decrypt in this session

int cipher_free_session(const struct device *dev, struct cipher_ctx *ctx)

Cleanup a crypto session.

Clears the hardware and/or driver state of a previous session.

Return

0 on success, negative errno code on fail.

Parameters

  • dev: Pointer to the device structure for the driver instance.

  • ctx: Pointer to the crypto context structure of the session to be freed.

int cipher_callback_set(const struct device *dev, crypto_completion_cb cb)

Registers an async crypto op completion callback with the driver.

The application can register an async crypto op completion callback handler to be invoked by the driver, on completion of a prior request submitted via crypto_do_op(). Based on crypto device hardware semantics, this is likely to be invoked from an ISR context.

Return

0 on success, -ENOTSUP if the driver does not support async op, negative errno code on other error.

Parameters

  • dev: Pointer to the device structure for the driver instance.

  • cb: Pointer to application callback to be called by the driver.

int cipher_block_op(struct cipher_ctx *ctx, struct cipher_pkt *pkt)

Perform single-block crypto operation (ECB cipher mode). This should not be overloaded to operate on multiple blocks for security reasons.

Return

0 on success, negative errno code on fail.

Parameters

  • ctx: Pointer to the crypto context of this op.

  • pkt: Structure holding the input/output buffer pointers.

int cipher_cbc_op(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *iv)

Perform Cipher Block Chaining (CBC) crypto operation.

Return

0 on success, negative errno code on fail.

Parameters

  • ctx: Pointer to the crypto context of this op.

  • pkt: Structure holding the input/output buffer pointers.

  • iv: Initialization Vector (IV) for the operation. Same IV value should not be reused across multiple operations (within a session context) for security.

int cipher_ctr_op(struct cipher_ctx *ctx, struct cipher_pkt *pkt, uint8_t *iv)

Perform Counter (CTR) mode crypto operation.

Return

0 on success, negative errno code on fail.

Parameters

  • ctx: Pointer to the crypto context of this op.

  • pkt: Structure holding the input/output buffer pointers.

  • iv: Initialization Vector (IV) for the operation. We use a split counter formed by appending IV and ctr. Consequently ivlen = keylen - ctrlen. ‘ctrlen’ is specified during session setup through the ‘ctx.mode_params.ctr_params.ctr_len’ parameter. IV should not be reused across multiple operations (within a session context) for security. The non-IV part of the split counter is transparent to the caller and is fully managed by the crypto provider.

int cipher_ccm_op(struct cipher_ctx *ctx, struct cipher_aead_pkt *pkt, uint8_t *nonce)

Perform Counter with CBC-MAC (CCM) mode crypto operation.

Return

0 on success, negative errno code on fail.

Parameters

  • ctx: Pointer to the crypto context of this op.

  • pkt: Structure holding the input/output, Assosciated Data (AD) and auth tag buffer pointers.

  • nonce: Nonce for the operation. Same nonce value should not be reused across multiple operations (within a session context) for security.

int cipher_gcm_op(struct cipher_ctx *ctx, struct cipher_aead_pkt *pkt, uint8_t *nonce)

Perform Galois/Counter Mode (GCM) crypto operation.

Return

0 on success, negative errno code on fail.

Parameters

  • ctx: Pointer to the crypto context of this op.

  • pkt: Structure holding the input/output, Associated Data (AD) and auth tag buffer pointers.

  • nonce: Nonce for the operation. Same nonce value should not be reused across multiple operations (within a session context) for security.

struct crypto_driver_api
#include <cipher.h>
struct cipher_ops
#include <cipher_structs.h>
struct ccm_params
#include <cipher_structs.h>
struct ctr_params
#include <cipher_structs.h>
struct gcm_params
#include <cipher_structs.h>
struct cipher_ctx
#include <cipher_structs.h>

Structure encoding session parameters.

Refer to comments for individual fields to know the contract in terms of who fills what and when w.r.t begin_session() call.

union cipher_ctx.key

To be populated by the app before calling begin_session()

Public Members

uint8_t *bit_stream
void *handle
union cipher_ctx.mode_params

Cypher mode parameters, which remain constant for all ops in a session. To be populated by the app before calling begin_session().

Public Members

struct ccm_params ccm_info
struct ctr_params ctr_info
struct gcm_params gcm_info
struct cipher_pkt
#include <cipher_structs.h>

Structure encoding IO parameters of one cryptographic operation like encrypt/decrypt.

The fields which has not been explicitly called out has to be filled up by the app before making the cipher_xxx_op() call.

struct cipher_aead_pkt
#include <cipher_structs.h>

Structure encoding IO parameters in AEAD (Authenticated Encryption with Associated Data) scenario like in CCM.

App has to furnish valid contents prior to making cipher_ccm_op() call.