Asymmetric Cipher Algorithm Definitions¶

structakcipher_request¶

public key request

Definition

struct akcipher_request {  struct crypto_async_request base;  struct scatterlist *src;  struct scatterlist *dst;  unsigned int src_len;  unsigned int dst_len;  void *__ctx[] ;};

Members

base

Common attributes for async crypto requests

src

Source dataFor verify op this is signature + digest, in that casetotal size ofsrc issrc_len +dst_len.

dst

Destination data (Should be NULL for verify op)

src_len

Size of the input bufferFor verify op it’s size of signature part ofsrc, this partis supposed to be operated by cipher.

dst_len

Size ofdst buffer (for all ops except verify).It needs to be at least as big as the expected resultdepending on the operation.After operation it will be updated with the actual size of theresult.In case of error where the dst sgl size was insufficient,it will be updated to the size required for the operation.For verify op this is size of digest part insrc.

__ctx

Start of private context data

structakcipher_alg¶

generic public key algorithm

Definition

struct akcipher_alg {  int (*sign)(struct akcipher_request *req);  int (*verify)(struct akcipher_request *req);  int (*encrypt)(struct akcipher_request *req);  int (*decrypt)(struct akcipher_request *req);  int (*set_pub_key)(struct crypto_akcipher *tfm, const void *key, unsigned int keylen);  int (*set_priv_key)(struct crypto_akcipher *tfm, const void *key, unsigned int keylen);  unsigned int (*max_size)(struct crypto_akcipher *tfm);  int (*init)(struct crypto_akcipher *tfm);  void (*exit)(struct crypto_akcipher *tfm);  unsigned int reqsize;  struct crypto_alg base;};

Members

sign

Function performs a sign operation as defined by public keyalgorithm. In case of error, where the dst_len was insufficient,the req->dst_len will be updated to the size required for theoperation

verify

Function performs a complete verify operation as defined bypublic key algorithm, returning verification status. Requiresdigest value as input parameter.

encrypt

Function performs an encrypt operation as defined by public keyalgorithm. In case of error, where the dst_len was insufficient,the req->dst_len will be updated to the size required for theoperation

decrypt

Function performs a decrypt operation as defined by public keyalgorithm. In case of error, where the dst_len was insufficient,the req->dst_len will be updated to the size required for theoperation

set_pub_key

Function invokes the algorithm specific set public keyfunction, which knows how to decode and interpretthe BER encoded public key and parameters

set_priv_key

Function invokes the algorithm specific set private keyfunction, which knows how to decode and interpretthe BER encoded private key and parameters

max_size

Function returns dest buffer size required for a given key.

init

Initialize the cryptographic transformation object.This function is used to initialize the cryptographictransformation object. This function is called only once atthe instantiation time, right after the transformation contextwas allocated. In case the cryptographic hardware has somespecial requirements which need to be handled by software, thisfunction shall check for the precise requirement of thetransformation and put any software fallbacks in place.

exit

Deinitialize the cryptographic transformation object. This is acounterpart toinit, used to remove various changes set ininit.

reqsize

Request context size required by algorithm implementation

base

Common crypto API algorithm data structure

Asymmetric Cipher API¶

The Public Key API is used with the algorithms of typeCRYPTO_ALG_TYPE_AKCIPHER (listed as type “akcipher” in /proc/crypto)

struct crypto_akcipher *crypto_alloc_akcipher(const char * alg_name, u32 type, u32 mask)¶

allocate AKCIPHER tfm handle

Parameters

constchar*alg_name

is the cra_name / name or cra_driver_name / driver name of thepublic key algorithm e.g. “rsa”

u32type

specifies the type of the algorithm

u32mask

specifies the mask for the algorithm

Description

Allocate a handle for public key algorithm. The returned structcrypto_akcipher is the handle that is required for any subsequentAPI invocation for the public key operations.

Return

allocated handle in case of success; IS_ERR() is true in case

of an error, PTR_ERR() returns the error code.

voidcrypto_free_akcipher(struct crypto_akcipher * tfm)¶

free AKCIPHER tfm handle

Parameters

structcrypto_akcipher*tfm

AKCIPHER tfm handle allocated withcrypto_alloc_akcipher()

unsigned intcrypto_akcipher_maxsize(struct crypto_akcipher * tfm)¶

Get len for output buffer

Parameters

structcrypto_akcipher*tfm

AKCIPHER tfm handle allocated withcrypto_alloc_akcipher()

Description

Function returns the dest buffer size required for a given key.Function assumes that the key is already set in the transformation. If thisfunction is called without a setkey or with a failed setkey, you will end upin a NULL dereference.

intcrypto_akcipher_encrypt(structakcipher_request * req)¶

Invoke public key encrypt operation

Parameters

structakcipher_request*req

asymmetric key request

Description

Function invokes the specific public key encrypt operation for a givenpublic key algorithm

Return

zero on success; error code in case of error

intcrypto_akcipher_decrypt(structakcipher_request * req)¶

Invoke public key decrypt operation

Parameters

structakcipher_request*req

asymmetric key request

Description

Function invokes the specific public key decrypt operation for a givenpublic key algorithm

Return

zero on success; error code in case of error

intcrypto_akcipher_sign(structakcipher_request * req)¶

Invoke public key sign operation

Parameters

structakcipher_request*req

asymmetric key request

Description

Function invokes the specific public key sign operation for a givenpublic key algorithm

Return

zero on success; error code in case of error

intcrypto_akcipher_verify(structakcipher_request * req)¶

Invoke public key signature verification

Parameters

structakcipher_request*req

asymmetric key request

Description

Function invokes the specific public key signature verification operationfor a given public key algorithm.

Note

req->dst should be NULL, req->src should point to SG of size(req->src_size + req->dst_size), containing signature (of req->src_sizelength) with appended digest (of req->dst_size length).

Return

zero on verification success; error code in case of error.

intcrypto_akcipher_set_pub_key(struct crypto_akcipher * tfm, const void * key, unsigned int keylen)¶

Invoke set public key operation

Parameters

structcrypto_akcipher*tfm

tfm handle

constvoid*key

BER encoded public key, algo OID, paramlen, BER encodedparameters

unsignedintkeylen

length of the key (not including other data)

Description

Function invokes the algorithm specific set key function, which knowshow to decode and interpret the encoded key and parameters

Return

zero on success; error code in case of error

intcrypto_akcipher_set_priv_key(struct crypto_akcipher * tfm, const void * key, unsigned int keylen)¶

Invoke set private key operation

Parameters

structcrypto_akcipher*tfm

tfm handle

constvoid*key

BER encoded private key, algo OID, paramlen, BER encodedparameters

unsignedintkeylen

length of the key (not including other data)

Description

Function invokes the algorithm specific set key function, which knowshow to decode and interpret the encoded key and parameters

Return

zero on success; error code in case of error

Asymmetric Cipher Request Handle¶

structakcipher_request *akcipher_request_alloc(struct crypto_akcipher * tfm, gfp_t gfp)¶

allocates public key request

Parameters

structcrypto_akcipher*tfm

AKCIPHER tfm handle allocated withcrypto_alloc_akcipher()

gfp_tgfp

allocation flags

Return

allocated handle in case of success or NULL in case of an error.

voidakcipher_request_free(structakcipher_request * req)¶

zeroize and free public key request

Parameters

structakcipher_request*req

request to free

voidakcipher_request_set_callback(structakcipher_request * req, u32 flgs, crypto_completion_t cmpl, void * data)¶

Sets an asynchronous callback.

Parameters

structakcipher_request*req

request that the callback will be set for

u32flgs

specify for instance if the operation may backlog

crypto_completion_tcmpl

callback which will be called

void*data

private data used by the caller

Description

Callback will be called when an asynchronous operation on a givenrequest is finished.

voidakcipher_request_set_crypt(structakcipher_request * req, struct scatterlist * src, struct scatterlist * dst, unsigned int src_len, unsigned int dst_len)¶

Sets request parameters

Parameters

structakcipher_request*req

public key request

structscatterlist*src

ptr to input scatter list

structscatterlist*dst

ptr to output scatter list or NULL for verify op

unsignedintsrc_len

size of the src input scatter list to be processed

unsignedintdst_len

size of the dst output scatter list or size of signatureportion insrc for verify op

Description

Sets parameters required by crypto operation