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Nostr Secret Key Seed Derivation for Hierarchical Deterministic Wallets (Draft)

Published Jul 3, 2026

Nostr Secret Key Seed Derivation for Hierarchical Deterministic Wallets (Draft)

Abstract

This proposal specifies a deterministic method for deriving a standard 64-byte BIP32 master seed from a Nostr secret key (nsec).

The purpose is to allow existing Nostr identities to serve as the root secret for Bitcoin Hierarchical Deterministic (HD) wallets while remaining fully compatible with the existing BIP32/BIP44/BIP84/BIP86 ecosystem.

This proposal defines only the seed generation process.

All subsequent key derivation SHALL follow existing Bitcoin standards.

Motivation

Many users already possess a securely backed-up Nostr secret key (nsec1...).

Today that key can authenticate across numerous applications, yet it cannot directly initialize a standard HD Bitcoin wallet.

Current wallets require one of:

  • BIP39 mnemonic
  • imported private key
  • hardware-generated seed

Importing a single private key does not provide deterministic address generation.

This proposal enables:

  • deterministic HD wallet recovery from an existing Nostr identity
  • optional passphrase protection
  • complete compatibility with existing BIP32 wallet infrastructure
  • a simple wallet import workflow requiring only an nsec and optional passphrase

Design Goals

  • No new elliptic curve algorithms
  • No changes to BIP32
  • No changes to BIP44/BIP84/BIP86
  • Simple implementation
  • Deterministic
  • Cross-wallet interoperable
  • Independent of any specific wallet vendor

Terminology

Nostr Secret Key

A Bech32-encoded Nostr private key beginning with:

nsec1...

defined by NIP-19.

Canonical Secret

The decoded 32-byte private key contained within the nsec.

Passphrase

An optional UTF-8 string supplied by the user.

An empty passphrase is permitted.

Seed Generation

Wallets SHALL accept an nsec1... string as input.

The wallet SHALL:

  1. Decode the Bech32 Nostr secret.
  2. Verify that exactly 32 bytes are produced.
  3. Apply PBKDF2-HMAC-SHA512.

Parameters:

Password:
    canonical 32-byte secret

Salt:
    "nostr" || passphrase

PRF:
    HMAC-SHA512

Iterations:
    2048

Output:
    64 bytes

The resulting 64-byte value SHALL be interpreted as a standard BIP32 master seed.

Master Key Generation

The seed SHALL be converted into a BIP32 master key exactly as defined by BIP32.

I = HMAC-SHA512(
    key = "Bitcoin seed",
    data = seed
)

master_private_key = I[0:32]

master_chain_code = I[32:64]

No modifications are introduced.

Child Key Derivation

All child derivation SHALL follow BIP32.

Recommended derivation paths include:

Legacy

m/44'/0'/0'/0/0

Nested SegWit

m/49'/0'/0'/0/0

Native SegWit

m/84'/0'/0'/0/0

Taproot

m/86'/0'/0'/0/0

Nothing in this proposal alters existing derivation paths.

Wallet Import Procedure

User interface example:

Import Wallet

Nostr Secret

nsec1...

Passphrase (optional)

********

Internally:

nsec1...
      │
      ▼
Bech32 Decode
      │
      ▼
32-byte Secret
      │
      ▼
PBKDF2-HMAC-SHA512
      │
      ▼
64-byte Seed
      │
      ▼
BIP32
      │
      ▼
BIP44/BIP84/BIP86

Reference Algorithm

seed = PBKDF2(
    password = decoded_nsec,
    salt = "nostr" || passphrase,
    iterations = 2048,
    hash = SHA512,
    output = 64 bytes
)

(master_key, chain_code) =
    BIP32_Master(seed)

Security Considerations

The security of the derived wallet depends entirely upon the entropy of the original Nostr private key.

Nostr private keys are uniformly random 256-bit values and therefore exceed the entropy requirements of typical mnemonic-based wallets.

Because the derivation is deterministic:

  • loss of the nsec results in loss of wallet recovery
  • compromise of the nsec compromises both Nostr identity and all wallets derived under this specification

Users SHOULD employ a passphrase when additional protection is desired.

Wallets SHOULD clearly warn users that importing an existing Nostr secret creates a cryptographic relationship between their Nostr identity and Bitcoin wallet.

Compatibility

This proposal is fully compatible with:

  • BIP32
  • BIP43
  • BIP44
  • BIP49
  • BIP84
  • BIP86

Only the generation of the initial seed differs.

No existing wallet functionality requires modification beyond accepting an nsec as an import source.

Test Vector Format

Each implementation SHOULD publish test vectors including:

Input nsec

Passphrase

Decoded Secret

Derived Seed

Master Private Key

Master Chain Code

m/44'/0'/0'/0/0

m/84'/0'/0'/0/0

m/86'/0'/0'/0/0