kcapi_cipher_decrypt — decrypt data (synchronous one shot)
int32_t kcapi_cipher_decrypt ( | struct kcapi_handle * handle, |
| const uint8_t * in, | |
| uint32_t inlen, | |
| const uint8_t * iv, | |
| uint8_t * out, | |
| uint32_t outlen, | |
int access); |
handle[in] cipher handle
in[in] ciphertext data buffer
inlen[in] length of in buffer
iv[in] IV to be used for cipher operation
out[out] plaintext data buffer
outlen[in] length of out bufferS
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 plaintext and ciphertext pointers. That would mean that after the encryption operation, the ciphertext is overwritten with the plaintext.
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.
The IV buffer must be exactly kcapi_cipher_ivsize bytes in size.
return number of bytes decrypted upon success;
a negative errno-style error code if an error occurred