Node.js crypto.hkdfSync( ) Method
Last Updated :
08 Apr, 2021
This method provides a synchronous HMAC-based Extract-and-Expand Key Derivation Function key derivation. Key of keylen bytes is derived using digest, given key, salt and info.
Syntax:
crypto.hkdfSync(digest, key, salt, info, keylen)
Parameters: This method has five parameters.
- digest: It must be string.
- key: Minimum lengths — 1 byte, It is of type string, Buffer,ArrayBuffer, TypedArray, KeyObject or DataView.
- salt: It must be provided but can be zero-length and unique. It can be of type string, ArrayBuffer, Buffer, TypedArray, or DataView.
- info: It must be provided but can be zero-length and cannot be more than 1024 bytes. It is of type string, Buffer,ArrayBuffer, TypedArray, KeyObject or DataView.
- keylen: It is the length of the key to generate and must be greater than 0. It must b of type number.
Return Type: Returns derived key int the form of buffer.
Example 1:
app.js
import crypto from 'crypto'
const Key = crypto.hkdfSync( 'sha512' , 'key' , 'salt' , 'info' , 64);
console.log(Key);
|
Output:
ArrayBuffer {
[Uint8Contents]: <24 15 6e 2c 35 52 5b
aa f3 d0 fb b9 2b 73 4c 80 32 a1 10 a3 f1 2e
25 96 e4 41 e1 92 48 70 d8 4c 3a 50 06 52 a7
23 73 80 24 43 24 51 04 6f d2 37 ef ad 83 92
fb 68 6c 52 77 a5 9e 01 05 39 16 53>,
byteLength: 64
}
Example 2:
app.js
import crypto from 'crypto'
const Key = crypto.hkdfSync( 'sha512' , 'key' , 'salt' , 'info' , 16);
console.log(Buffer.from(Key).toString( 'hex' ));
|
Output:
24156e2c35525baaf3d0fbb92b734c80
Example 3:
Javascript
import crypto from 'crypto'
const Key = crypto.hkdfSync( 'sha512' , 'key' , 'salt' , 'info' , 32);
console.log(Buffer.from(Key).toString( 'base64' ));
|
Output:
JBVuLDVSW6rz0Pu5K3NMgDKhEKPxLiWW5EHhkkhw2Ew=
Example 4:
Javascript
import crypto from 'crypto'
const Key = crypto.hkdfSync( 'sha512' , 'key' , 'salt' , 'info' , 32);
console.log(Buffer.from(Key).toString( 'ascii' ));
|
Output:
$n,5R[*sP{9+sL 2!#q.%dAaHpXL
Reference : https://nodejs.org/api/crypto.html#crypto_crypto_hkdfsync_digest_key_salt_info_keylen
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