NAME

       kcapi_akcipher_verify - signature verification

SYNOPSIS

       ssize_t kcapi_akcipher_verify(struct kcapi_handle * handle, const uint8_t * in,
                                     size_t inlen, uint8_t * out, size_t outlen, int access);

ARGUMENTS

       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)

DESCRIPTION

       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.

       To catch signature verification errors, the return value of this call should be checked.
       If this function returns -EBADMSG, the verification of the signature failed.

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

AUTHOR

       Stephan Mueller <smueller@chronox.de>
           Author.

COPYRIGHT