Deterministic Derivation

POST /keys/{keyId}/derive

Dfns decentralized key management network supports threshold Diffie-Hellman protocol based on GLOW20 paper. You can use the DH protocol to derive output from a domain separation tag and a seed value. The derivation process is deterministic, i.e. the same Diffie-Hellman key and seed will lead to the same derived output. To ensure reproducibility, we use hash to curve RFC9380 and standard ciphersuite secp256k1_XMD:SHA-256_SSWU_RO_.

The seed doesn’t need to be secret. Without access to the DH key, it is not possible to do the derivation, even if the seed is known. Moreover, if both seed and derived output are known, it’s also not possible to do the derivation for another seed without having access to the DH key.

This endpoint only supports Diffie-Hellman keys. Regular threshold signature keys, like ECDSA or EdDSA, will not work. You can create a Diffie-Hellman key with the Create Key endpoint using scheme=DH and curve=secp256k1.

Required Permissions

Name	Conditions
Keys:Derive	Always Required

Parameters

Path parameters

Path parameter	Description
keyId	Unique identifier of the key.

Request Body

Field	Description	Type - Optional
domain	Domain separation tag in hex-encoded format. Used to ensure the same seed will generate different outputs for different applications. For example, a DST can be {company}:{application}:{version}.	String
seed	Seed value in hex-encoded format.	String

Example

{
  "domain": "0x64666e733a646f63756d656e746174696f6e3a6b65795f646572697665",
  "seed": "0x64616e69656c2e6a696e4064666e732e636f"
}

Response Body

Field	Description	Type - Optional
output	Derivation output in hex-encoded format.	String

200 Success

{
  "output": "0x543feac809a7fcb4aea9516e9eb82b9fc6f234e214bbd53145b7bbc0f3be0c57"
}