1KCAPI_AEAD_DECRYPT(3)        Programming Interface       KCAPI_AEAD_DECRYPT(3)
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NAME

6       kcapi_aead_decrypt - synchronously decrypt AEAD data (one shot)
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SYNOPSIS

9       ssize_t kcapi_aead_decrypt(struct kcapi_handle * handle,
10                                  const uint8_t * in, size_t inlen,
11                                  const uint8_t * iv, uint8_t * out,
12                                  size_t outlen, int access);
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ARGUMENTS

15       handle
16           [in] cipher handle
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18       in
19           [in] ciphertext data buffer
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21       inlen
22           [in] length of in buffer
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24       iv
25           [in] IV to be used for cipher operation
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27       out
28           [out] plaintext data buffer
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30       outlen
31           [in] length of out buffer
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33       access
34           [in] kernel access type (KCAPI_ACCESS_HEURISTIC - use internal
35           heuristic for fastest kernel access; KCAPI_ACCESS_VMSPLICE use
36           vmsplice access; KCAPI_ACCESS_SENDMSG sendmsg access)
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DESCRIPTION

39       The AEAD cipher operation requires the furnishing of the associated
40       authentication data. In case such data is not required, it can be set
41       to NULL and length value must be set to zero.
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43       It is perfectly legal to use the same buffer as the plaintext and
44       ciphertext pointers. That would mean that after the encryption
45       operation, the ciphertext is overwritten with the plaintext.
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47       The memory should be aligned at the page boundary using
48       posix_memalign(sysconf(_SC_PAGESIZE)), If it is not aligned at the page
49       boundary, the vmsplice call may not send all data to the kernel.
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51       The IV buffer must be exactly kcapi_cipher_ivsize bytes in size.
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53       To catch authentication errors (i.e. integrity violations) during the
54       decryption operation, the return value of this call should be checked.
55       If this function returns -EBADMSG, an authentication error was
56       detected.
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IMPORTANT NOTE

59       The kernel will only process sysconf(_SC_PAGESIZE) * ALG_MAX_PAGES at
60       one time. Longer input data cannot be handled by the kernel.
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62       return number of bytes decrypted upon success; a negative errno-style
63       error code if an error occurred
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AUTHOR

66       Stephan Mueller <smueller@chronox.de>
67           Author.
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70libkcapi Manual 1.4.0              July 2023             KCAPI_AEAD_DECRYPT(3)
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