SLH-DSA Sign (FIPS 205)

Category: Post-Quantum Cryptography · Node Type ID: pqc-slhdsa-sign

Signs message using stateless hash-based signature scheme (FIPS 205)

Overview

Signs a message using the stateless hash-based signature scheme SLH-DSA (NIST FIPS 205). Use the 128f (fast) parameter sets when interactive signing latency is important, or 128s (small) when minimizing signature byte size (7,856 bytes vs. 17,088 bytes) is preferred.

When to Use

Creating stateless hash-based post-quantum signatures with a keypair from SLH-DSA KeyGen.

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Parameter Set `variant`	`select` Default: `slh_dsa_sha2_128s`	Always visible	Must match the FIPS 205 parameter set of the connected `Secret Key`. `slh_dsa_sha2_128s`: SLH-DSA-SHA2-128s `slh_dsa_sha2_128f`: SLH-DSA-SHA2-128f `slh_dsa_shake_128s`: SLH-DSA-SHAKE-128s `slh_dsa_shake_128f`: SLH-DSA-SHAKE-128f `slh_dsa_sha2_256s`: SLH-DSA-SHA2-256s `slh_dsa_shake_256s`: SLH-DSA-SHAKE-256s

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
`Secret Key`	`secretKey`	`Bytes`	Required	Always visible	Signer's SLH-DSA secret key (64B for 128-bit sets, 128B for 256-bit sets).
`Message Data`	`message`	`Bytes`	Required	Always visible	Message bytes (`Uint8Array`) to sign.

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Signature`	`signature`	`Bytes`	Always visible	Computed SLH-DSA signature (7,856B for 128s, 17,088B for 128f, 29,792B for 256s).

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_KEY_MATERIAL`	Invalid key length or format	Raised when `Secret Key` length does not match the selected SLH-DSA parameter set.

Examples

Signing Firmware Data with SLH-DSA

Sign a message using SLH-DSA-SHA2-128f.

Select SLH-DSA-SHA2-128f (Fast), connect the 64-byte Secret Key and Message Data, and wire Signature to SLH-DSA Verify.