1KCAPI_KDF_CTR(3)             Programming Interface            KCAPI_KDF_CTR(3)
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NAME

6       kcapi_kdf_ctr - Counter Mode Key Derivation Function
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SYNOPSIS

9       ssize_t kcapi_kdf_ctr(struct kcapi_handle * handle,
10                             const uint8_t * src, size_t slen, uint8_t * dst,
11                             size_t dlen);
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ARGUMENTS

14       handle
15           [in] cipher handle allocated by caller. This cipher handle must be
16           allocated with kcapi_md_init. If the caller is interested in a KDF
17           using a keyed message digest, the caller should also call
18           kcapi_md_setkey before invoking this function.
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20       src
21           [in] Input data that should be transformed into a key (see below).
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23       slen
24           [in] Length of the src input data.
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26       dst
27           [out] Buffer to store the generated key in,
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29       dlen
30           [in] Length of the dst buffer. This value defines the number of
31           bytes generated by the KDF.
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DESCRIPTION

34       This function is an implementation of the KDF in counter mode according
35       to SP800-108 section 5.1 as well as SP800-56A section 5.8.1
36       (Single-step KDF).
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38       SP800-108: The caller must provide Label || 0x00 || Context in src.
39       This src pointer may also be NULL if the caller wishes not to provide
40       anything.
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42       SP800-56A: If a keyed MAC is used, the key shall NOT be the shared
43       secret from the DH operation, but an independently generated key. The
44       src pointer is defined as Z || other info where Z is the shared secret
45       from DH and other info is an arbitrary string (see SP800-56A section
46       5.8.1.2).
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48       return 0 upon success; a negative errno-style error code if an error
49       occurred
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AUTHOR

52       Stephan Mueller <smueller@chronox.de>
53           Author.
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56libkcapi Manual 1.4.0            January 2023                 KCAPI_KDF_CTR(3)
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