NAME

       kcapi_aead_decrypt - synchronously decrypt AEAD data (one shot)

SYNOPSIS

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

ARGUMENTS

       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 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

       The AEAD cipher operation requires the furnishing of the associated authentication data.
       In case such data is not required, it can be set to NULL and length value must be set to
       zero.

       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.

       To catch authentication errors (i.e. integrity violations) during the decryption
       operation, the return value of this call should be checked. If this function returns
       -EBADMSG, an authentication error was detected.

IMPORTANT NOTE

       The kernel will only process sysconf(_SC_PAGESIZE) * ALG_MAX_PAGES at one time. Longer
       input data cannot be handled by the kernel.

       return number of bytes decrypted upon success; a negative errno-style error code if an
       error occurred

AUTHOR

       Stephan Mueller <smueller@chronox.de>
           Author.

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