nbitcoin

Generate a Mnemonic

```csharp

// src/Common/Sorcha.Wallet.Core/Domain/ValueObjects/Mnemonic.cs

var mnemonic = Mnemonic.Generate(12); // or 24 for higher security

// NEVER log mnemonic.Phrase - use mnemonic.ToString() which returns "Mnemonic(12 words)"

```

Derive Keys at BIP44 Path

```csharp

// src/Common/Sorcha.Wallet.Core/Services/Implementation/KeyManagementService.cs:62-111

var masterKey = await _keyManagement.DeriveMasterKeyAsync(mnemonic, passphrase);

var path = DerivationPath.CreateBip44(coinType: 0, account: 0, change: 0, addressIndex: 0);

var (privateKey, publicKey) = await _keyManagement.DeriveKeyAtPathAsync(masterKey, path, "ED25519");

```

Validate a Mnemonic

```csharp

if (Mnemonic.IsValid(userProvidedPhrase))

{

var mnemonic = new Mnemonic(userProvidedPhrase);

}

```

| Concept | Usage | Example |

|---------|-------|---------|

| Mnemonic | Wraps NBitcoin.Mnemonic | Mnemonic.Generate(12) |

| DerivationPath | Wraps NBitcoin.KeyPath | DerivationPath.CreateBip44(0, 0, 0, 0) |

| ExtKey | Extended private key | ExtKey.CreateFromSeed(masterKey) |

| System Paths | Sorcha-specific aliases | "sorcha:register-attestation" → "m/44'/0'/0'/0/100" |

| Gap Limit | BIP44: max 20 unused addresses | Enforced in WalletManager.cs:493-508 |

Wallet Creation Flow

When: User creates a new wallet.

```csharp

// 1. Generate mnemonic (NEVER store on server)

var mnemonic = Mnemonic.Generate(12);

// 2. Derive master key with optional passphrase

var masterKey = await _keyManagement.DeriveMasterKeyAsync(mnemonic, passphrase);

// 3. Derive first key at m/44'/0'/0'/0/0

var path = DerivationPath.CreateBip44(0, 0, 0, 0);

var (privateKey, publicKey) = await _keyManagement.DeriveKeyAtPathAsync(masterKey, path, algorithm);

// 4. Encrypt private key before storage

var (encryptedKey, keyId) = await _keyManagement.EncryptPrivateKeyAsync(privateKey, string.Empty);

```

System Path Resolution

When: Using Sorcha-specific derivation purposes.

```csharp

// src/Common/Sorcha.Wallet.Core/Constants/SorchaDerivationPaths.cs

var resolvedPath = SorchaDerivationPaths.IsSystemPath(derivationPath)

? SorchaDerivationPaths.ResolvePath(derivationPath) // "sorcha:register-attestation" → "m/44'/0'/0'/0/100"

: derivationPath;

```

• [patterns](references/patterns.md) - Value objects, key derivation, security patterns
• [workflows](references/workflows.md) - Wallet creation, recovery, address management

• See the cryptography skill for signing operations (ED25519, P-256, RSA-4096)
• See the dotnet skill for .NET 10 patterns and DI configuration
• See the xunit skill and fluent-assertions skill for testing HD wallet operations

> Fetch latest NBitcoin documentation with Context7.

How to use Context7:

1. Use mcp__context7__resolve-library-id to search for "nbitcoin"
2. Query with mcp__context7__query-docs using the resolved library ID

Library ID: /metacosa/nbitcoin

Recommended Queries:

• "NBitcoin BIP32 BIP39 BIP44 key derivation"
• "NBitcoin ExtKey master key child derivation"
• "NBitcoin Mnemonic passphrase seed"