AzelusLightvale-ComfyUI-ARG-Toolkit/web/docs/KBKDF_Derive.md

KBKDF Key Derivation

Derives a key using the Key-Based Key Derivation Function (KBKDF) in Counter Mode.

Source library: cryptography

Overview

This node implements the KDF specified in NIST SP 800-108. It is designed to derive additional cryptographic keys from a single master key (Ki). The function uses a pseudorandom function (PRF), such as HMAC or CMAC, in a counter mode construction.

Parameters

• message: The master key (Ki) to derive from, as a BYTESLIKE object.
• length: The desired length of the derived key in bytes.
• algorithm: The hash function to use for the underlying PRF (e.g., SHA256).
• operation_mode: The PRF to use.
  • KBKDFHMAC: Uses HMAC as the PRF.
  • KBKDFCMAC: Uses CMAC as the PRF. (Note: CMAC requires an underlying block cipher like AES, which is not exposed as an option in this node and may lead to errors if not configured correctly in the backend).
• location: The position of the counter within the data fed to the PRF (BeforeFixed, AfterFixed, MiddleFixed).
• rlen: The length of the counter field in bytes.
• llen: The length of the output key length field in bytes.
• label: (Optional) A BYTESLIKE string identifying the purpose of the derived key.
• context: (Optional) BYTESLIKE information related to the context of the derived key.
• fixed: (Optional) Instead of label and context, you can supply fixed data in this field. If specified, label and context are ignored.
• break_location: (Optional) When location is MiddleFixed, this specifies the byte offset where the counter is inserted.

Outputs

• derived_key: The resulting derived key as a BYTESLIKE object.