1KCAPI_AKCIPHER_VERIF(3)      Programming Interface     KCAPI_AKCIPHER_VERIF(3)
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NAME

6       kcapi_akcipher_verify - signature verification
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SYNOPSIS

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

15       handle
16           [in] cipher handle
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18       in
19           [in] message data buffer
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21       inlen
22           [in] length of in buffer
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24       out
25           [out] signature data buffer
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27       outlen
28           [in] length of out buffer
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30       access
31           [in] kernel access type (KCAPI_ACCESS_HEURISTIC - use internal
32           heuristic for fastest kernel access; KCAPI_ACCESS_VMSPLICE - use
33           vmsplice access; KCAPI_ACCESS_SENDMSG - sendmsg access)
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DESCRIPTION

36       It is perfectly legal to use the same buffer as the message and
37       signature pointers. That would mean that after the signature generation
38       operation, the message is overwritten with the signature.
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40       The memory should be aligned at the page boundary using
41       posix_memalign(sysconf(_SC_PAGESIZE)), If it is not aligned at the page
42       boundary, the vmsplice call may not send all data to the kernel.
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44       If the output size is insufficiently large, -EINVAL is returned. The
45       output buffer must be at least as large as the modululs of the uses
46       key.
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48       To catch signature verification errors, the return value of this call
49       should be checked. If this function returns -EBADMSG, the verification
50       of the signature failed.
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52       return number of bytes returned by the signature ver operation upon
53       success; a negative errno-style error code if an error occurred
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AUTHOR

56       Stephan Mueller <smueller@chronox.de>
57           Author.
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60libkcapi Manual 1.4.0              July 2023           KCAPI_AKCIPHER_VERIF(3)
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