PBKDF2 Key Derivation

Category: Key Derivation · Node Type ID: kdf-pbkdf2

Password-Based Key Derivation Function 2 (RFC 8018)

Overview

Derives a cryptographic secret key of configurable byte length from a password or passphrase using PBKDF2 (Password-Based Key Derivation Function 2, PKCS #5 v2.1 / RFC 8018 / NIST SP 800-132) with HMAC-SHA256 or HMAC-SHA512 as the pseudorandom function (PRF).

PBKDF2 applies the PRF iteratively (controlled by Iterations) to slow down brute-force and dictionary attacks against human-chosen passwords. If the optional Salt input port is left unconnected, the node defaults to 16 zero bytes (0x00 * 16) for deterministic testing.

When to Use

Stretching a user password or passphrase into a 16-, 24-, or 32-byte symmetric encryption key for AES, ChaCha20-Poly1305, or HMAC.
Reproducing PKCS #5 / RFC 6070 / keystore key-derivation test vectors.

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Iterations `iterations`	`number` Default: `10000` Supports Variable Reference (`$var`: `int`)	Always visible	Number of HMAC iteration rounds (clamped to `1..1,000,000`; default `10000`). Higher counts increase resistance to brute-force attacks at the cost of execution time.
Output Key Length (bytes) `keyLength`	`number` Default: `32` Supports Variable Reference (`$var`: `int`)	Always visible	Desired output key length in bytes (clamped to `1..512`; default `32` for a 256-bit key).
PR Hash Function `hashAlgorithm`	`select` Default: `SHA-256`	Always visible	Underlying HMAC pseudorandom function: `SHA-256` or `SHA-512`. `SHA-256`: SHA-256 `SHA-512`: SHA-512

Port I/O Specification

See Ports & Connections for general wiring rules, data type colors, and dynamic port creation.

Input Ports

Port Nature: Fixed Input Ports (2 total).

Port Name	Port ID	Data Type	Required	Visibility Condition	Description
`Password`	`password`	`Bytes`	Required	Always visible	Password or secret byte array (`Uint8Array`; must be at least 1 byte). Connect String to Bytes if starting from text.
`Salt`	`salt`	`Bytes`	Optional	Always visible	Optional salt byte array (`Uint8Array`). Defaults to 16 zero bytes if unconnected; connect a Random Generator (16B) in real protocols.

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Derived Key`	`derivedKey`	`Bytes`	Always visible	Derived cryptographic key material (`Uint8Array`) of `Output Key Length` bytes.

Error Cases

When any of the following conditions occurs at runtime, this node transitions to an ERROR state and downstream nodes connected to its outputs do not execute.

Error Code	Default Engine Message	Trigger Condition
`INVALID_KDF_PARAMS`	Invalid KDF parameters	Raised when the KDF input secret/password is empty or the requested output length/iterations are outside the valid range.

Examples

Deriving a 256-bit AES Key from a Passphrase and Random Salt

Stretch a UTF-8 passphrase into a 32-byte key using 10,000 iterations of PBKDF2-HMAC-SHA256.

Encode your passphrase with String to Bytes and connect it to Password / Secret.
Connect a 16-byte Random Generator to Salt, leave Output Key Length at 32, and wire Derived Key to AES Encrypt.