@solana-keychain/vault

HashiCorp Vault-based signer for Solana transactions using Vault's transit engine.

Installation

``bash
npm install @solana-keychain/vault
`

Prerequisites

1. A HashiCorp Vault instance with the transit engine enabled
2. An ED25519 key created in the transit engine
3. A Vault token with sign permissions for the key

$3

`bash


Enable the transit engine

vault secrets enable transit

Create an ED25519 key

vault write transit/keys/my-solana-key type=ed25519

Export the public key to get your Solana address

vault read -field=keys transit/export/signing-key/my-solana-key/1
`

Usage

$3

`typescript
import { VaultSigner } from '@solana-keychain/vault';

const signer = new VaultSigner({
vaultAddr: 'https://vault.example.com',
vaultToken: 'hvs.your-vault-token',
keyName: 'my-solana-key',
publicKey: 'your-solana-public-key-base58', // Must match the Vault key
});

// Check if the signer is available
const isAvailable = await signer.isAvailable();
console.log('Vault signer available:', isAvailable);
`

$3

`typescript
import { pipe } from '@solana/functional';
import { createTransaction } from '@solana/transactions';
import { signTransaction } from '@solana/signers';

// Create your transaction
const transaction = pipe(
createTransaction({ version: 0 }),
// ... add instructions
);

// Sign the transaction
const signedTransaction = await signTransaction([signer], transaction);
`

$3

`typescript
import { signMessage } from '@solana/signers';

const message = new TextEncoder().encode('Hello, Solana!');
const signature = await signMessage([signer], message);
`

$3

If you're signing multiple transactions/messages concurrently and want to avoid rate limits:

`typescript
const signer = new VaultSigner({
vaultAddr: 'https://vault.example.com',
vaultToken: 'hvs.your-vault-token',
keyName: 'my-solana-key',
publicKey: 'your-solana-public-key',
requestDelayMs: 100, // 100ms delay between concurrent requests
});
`

Configuration

$3

| Field | Type | Required | Description |
|-------|------|----------|-------------|
| vaultAddr | string | Yes | Vault server address (e.g., https://vault.example.com) |
| vaultToken | string | Yes | Vault authentication token |
| keyName | string | Yes | Name of the transit key in Vault |
| publicKey | string | Yes | Solana public key (base58) corresponding to the Vault key |
| requestDelayMs | number | No | Delay in ms between concurrent signing requests (default: 0) |

Vault Permissions

The Vault token must have the following permissions on the transit key:

`hcl
path "transit/sign/my-solana-key" {
capabilities = ["update"]
}

path "transit/keys/my-solana-key" {
capabilities = ["read"]
}
`

Error Handling

The signer will throw errors with specific codes from @solana-keychain/core:

- CONFIG_ERROR - Invalid configuration
- HTTP_ERROR - Network request failed
- REMOTE_API_ERROR - Vault API returned an error
- PARSING_ERROR - Failed to parse Vault response

`typescript
import { SignerErrorCode } from '@solana-keychain/core';

try {
await signer.signMessages([message]);
} catch (error) {
if (error.code === SignerErrorCode.REMOTE_API_ERROR) {
console.error('Vault API error:', error.message);
}
}
``

Security Considerations

1. Token Security: Never hardcode Vault tokens. Use environment variables or secure secret management.
2. TLS: Always use HTTPS when connecting to Vault.
3. Token Rotation: Implement token rotation and use short-lived tokens when possible.
4. Audit Logging: Enable Vault audit logging to track signing operations.

License

MIT