kcapi_kdf_ctr - Man Page
Counter Mode Key Derivation Function
Synopsis
ssize_t kcapi_kdf_ctr(struct kcapi_handle * handle, const uint8_t * src, size_t slen, uint8_t * dst, size_t dlen);
Arguments
handle
[in] cipher handle allocated by caller. This cipher handle must be allocated with kcapi_md_init. If the caller is interested in a KDF using a keyed message digest, the caller should also call kcapi_md_setkey before invoking this function.
src
[in] Input data that should be transformed into a key (see below).
slen
[in] Length of the src input data.
dst
[out] Buffer to store the generated key in,
dlen
[in] Length of the dst buffer. This value defines the number of bytes generated by the KDF.
Description
This function is an implementation of the KDF in counter mode according to SP800-108 section 5.1 as well as SP800-56A section 5.8.1 (Single-step KDF).
SP800-108: The caller must provide Label || 0x00 || Context in src. This src pointer may also be NULL if the caller wishes not to provide anything.
SP800-56A: If a keyed MAC is used, the key shall NOT be the shared secret from the DH operation, but an independently generated key. The src pointer is defined as Z || other info where Z is the shared secret from DH and other info is an arbitrary string (see SP800-56A section 5.8.1.2).
return 0 upon success; a negative errno-style error code if an error occurred
Author
Stephan Mueller <smueller@chronox.de>
Author.