> ## Documentation Index
> Fetch the complete documentation index at: https://notevil.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CAPLfunctionSecurityLocalDeriveConcatKdf

# SecurityLocalDeriveConcatKdf

[Valid for](../../../Shared/FeatureAvailability.md):  CANoe DE • CANoe4SW DE

## Function Syntax

```
long SecurityLocalDeriveConcatKdf(dword hashAlgorithm, byte secret[], dword secretLength, byte label[], dword labelLength, dword keyLength, byte outputKey[] [OUT]);
```

## Description

Derive a key using the Concatenation KDF (NIST SP 800-56A).

This is the Concatenation Key Derivation Function as defined in [section 5.8.1 of NIST SP 800-56A Rev. 1](https://csrc.nist.gov/pubs/sp/800/56/a/r1/final).

It is the same as the One-step Key Derivation as defined in [section 5.8.2.1 of NIST SP 800-56A Rev. 3](https://csrc.nist.gov/pubs/sp/800/56/a/r3/final) with the Concatenation Format for FixedInfo (section 5.8.2.1.1), if the one-step key-derivation method specified in SP 800-56C is used with H = hash.

Note that it is upon the user to ensure that the provided label satisfies the requirements from NIST SP 800-56A.

## Parameters

* **dword hashAlgorithm**\
  ID of the hash algorithm to use.\
  Available hash algorithm:
  * SHA-256 = 1
  * SHA-384 = 2
  * SHA-512 = 3
  * SHA-224 = 4
  * SM3 = 5

* **byte secret\[]**\
  The secret to derive the key from.

* **dword secretLength**\
  The length of the secret.

* **byte label\[]**\
  A string identifying the purpose of the derived key (also called OtherInfo or FixedInfo).

* **dword labelLength**\
  The length of the label.

* **dword keyLength**\
  The length of the key to derive.

* **byte outputKey\[] \[OUT]**\
  Output buffer for the derived key.

## Return Values

* **1**\
  Success. A value of 1 means that the action was successful.

* **\<= 0**\
  Error. A value less than or equal to 0 means error.

## Example

```c theme={null}
dword hashAlgorithm = 1; // SHA-256
byte secret[16] = {0xE3, 0xC0, 0x8A, 0x8F, 0x06, 0xC6, 0xE3, 0xAD, 0x95, 0xA7, 0x05, 0x57, 0xB2, 0x3F, 0x75, 0x48};
byte label[3] = {0x01, 0x55, 0x56};
byte derivedKey[16];
long result;
result = SecurityLocalDeriveConcatKdf(hashAlgorithm, secret, elCount(secret), label, elCount(label), elCount(derivedKey), derivedKey);
```

[SecurityLocalSignRsa](CAPLfunctionSecurityLocalSignRSA.md) • [SecurityLocalEncryptRsa](CAPLfunctionSecurityLocalEncryptRsa.md) • [SecurityLocalVerifyRsa](CAPLfunctionSecurityLocalVerifyRSA.md)