# Self-custody exit overview

Executive summary
**You can hold your own independent copy of your vault's key material and use it to sign blockchain transactions, even if Ripple Custody is unavailable.**

- Ripple Custody backs up your vault key material for its own disaster recovery. Separately, from version 1.29, you can request, verify, and keep your own copy.
- You use that copy with the `rkit-cli` recovery tool to produce a valid cryptographic signature for any of your blockchain accounts.
- The recovery works without the Ripple Custody application running.
- This capability applies to HSM-backed and software-wrapped vaults, not to MPC vaults.


Why this matters
This is your insurance policy. You don't need it during normal operation. It exists for the scenario where Ripple Custody is not available to you and you need to prove, and exercise, your ownership of the assets it safeguarded.

## Scope

This procedure produces a raw digital signature from your recovered key material. It doesn't cover building a complete, broadcastable transaction, submitting a transaction to a blockchain network, or moving funds to a new destination. Those steps are chain-specific, and you own them.

MPC vaults use a different mechanism
This procedure applies to HSM-backed and software-wrapped vaults only. If your vault uses Ripple Custody MPC (multi-party computation) key management, the recovery mechanism is entirely different. See [MPC backups and exit strategy](/products/custody/deployment/integrate-kms/mpc/backups) instead.

## How key recovery works

A **private key**, a large secret number, controls a blockchain account. Anyone who has it can authorize ("sign") transactions that move the account's funds. The matching **public key** lets everyone else verify that a signature came from that private key, without ever learning the private key itself. Your account's **address** derives from its public key.

Rather than store one private key per account, Ripple Custody stores a single secret value called a **seed** and derives as many key pairs as it needs from it, one per account per blockchain, through **hierarchical deterministic (HD) derivation**. A **derivation path** reaches each key pair from the seed: a short string such as `m/1'/1'` that acts like an address within the tree of possible keys. The same seed and the same path always produce the same key pair.

Because the seed is so sensitive, Ripple Custody never stores it in the clear. A **hardware security module (HSM)**, a tamper-resistant device that stores and uses cryptographic material without exposing it, wraps (encrypts) the seed. Software-only deployments wrap the seed with an equivalent software mechanism.

To recover a key pair and produce a signature, you don't need the Ripple Custody application. You need only three things:

- Your wrapped seed.
- The derivation path for the account you care about.
- Access to the HSM (or software equivalent) that can unwrap the seed and perform the signing operation.


## Supported blockchains

`rkit-cli` can recover keys and produce signatures for Bitcoin, Ethereum, Tron, XRPL, Algorand, Cardano, Diem, Hedera, Polkadot / Substrate, Solana, Stellar, and Tezos. For the signature scheme, curve, and pre-hash of each chain, see the [chain signature reference](/products/custody/operations-and-maintenance/backup-and-restore/recover-hsm-keys#chain-signature-reference).

## Prepare before a disaster

Recovery depends on materials you must have in hand before you need them. Confirm now that you have:

- Access to Ripple Custody version 1.29 or later.
- Your organization's HSM PIN and partition credentials, or the equivalent software key material.
- The `rkit-cli` package that matches your HSM provider. Ripple shares this with you through SendSafely. Store it securely, ahead of any disaster.
- A team member who is comfortable running command-line tools. The [recovery procedure](/products/custody/operations-and-maintenance/backup-and-restore/recover-hsm-keys) is technical.
- For a hardware HSM, network access from wherever you run `rkit-cli` to your HSM cluster.


## Glossary

| Term | Meaning |
|  --- | --- |
| Seed (master seed) | The single secret value that all of a vault's key pairs derive from. |
| Wrapping key (WK) | The key an HSM uses to encrypt ("wrap") the seed so it's never stored or transmitted in the clear. |
| HSM | Hardware security module: a tamper-resistant device that stores and uses cryptographic material without exposing it. |
| Trusted-entity envelope | The signed package Ripple Custody returns when you fetch a backup: the wrapped seed plus a signature you can verify. |
| Derivation path | A short string (for example, `m/1'/1'`) that identifies exactly which key pair to derive from the seed. |
| Curve | The elliptic curve used for a chain's signatures: secp256k1 (ECDSA chains) or Ed25519 (EdDSA chains). |
| SLIP-10 / BIP-32 | The two closely related standards that describe how to derive child key pairs from a seed for Ed25519 and secp256k1, respectively. |
| CKD | Child key derivation: the function that turns a seed or parent key plus a path segment into a child key pair. |
| KMS | Key management service. |


## Next steps

- [Recover keys and sign with rkit-cli](/products/custody/operations-and-maintenance/backup-and-restore/recover-hsm-keys): the step-by-step recovery procedure, with the full flag and chain signature reference.
- [Back up, restore, and recover](/products/custody/operations-and-maintenance/backup-and-restore): all Ripple Custody backup and recovery procedures.