DOKK / manpages / debian 11 / libkcapi-dev / kcapi_akcipher_sign.3.en
KCAPI_AKCIPHER_SIGN(3) Programming Interface KCAPI_AKCIPHER_SIGN(3)

kcapi_akcipher_sign - signature generation

int32_t kcapi_akcipher_sign(struct kcapi_handle * handle, const uint8_t * in, uint32_t inlen, uint8_t * out, uint32_t outlen, int access);

handle

[in] cipher handle

in

[in] message data buffer

inlen

[in] length of in buffer

out

[out] signature data buffer

outlen

[in] length of out buffer

access

[in] kernel access type (KCAPI_ACCESS_HEURISTIC - use internal heuristic for fastest kernel access; KCAPI_ACCESS_VMSPLICE - use vmsplice access; KCAPI_ACCESS_SENDMSG - sendmsg access)

It is perfectly legal to use the same buffer as the message and signature pointers. That would mean that after the signature generation operation, the message is overwritten with the signature.

The memory should be aligned at the page boundary using posix_memalign(sysconf(_SC_PAGESIZE)), If it is not aligned at the page boundary, the vmsplice call may not send all data to the kernel.

If the output size is insufficiently large, -EINVAL is returned. The output buffer must be at least as large as the modululs of the uses key.

return number of bytes returned by the signature gen operation upon success; a negative errno-style error code if an error occurred

Stephan Mueller <smueller@chronox.de>

Author.

November 2020 libkcapi Manual 1.2.1