--- title: "Key Recovery" description: "Rebuild a wallet private key offline from the Fystack key share and your cosigner share using Fystack Recovery." url: https://docs.fystack.io/cosigner/recovery last_updated: 2026-10-25 --- > ## Documentation index > Fetch the complete documentation index at: https://docs.fystack.io/llms.txt > Use it to discover all available pages before exploring further. # Key Recovery [Fystack Recovery](https://github.com/fystack/cosigner-recovery) rebuilds a wallet's private keys offline from a threshold of key shares. Use it to leave Fystack, migrate a wallet, or regain funds if Fystack is unavailable. > **Note:** Recovery materializes the full private key and removes the wallet's threshold security. Only run it on an offline machine, and only for recovery or migration. ## Overview _Diagram: The Fystack share is exported from the dashboard as an RSA-sealed .enc bundle, the cosigner share is exported as a passphrase-sealed .mshare, and Fystack Recovery on an air-gapped machine unlocks, combines and verifies them into ECDSA and EdDSA keys_ Each signer exports its own share, encrypted: - **Fystack share**: exported from the dashboard as an `.enc` RSA bundle, sealed to an RSA public key you provide. - **Cosigner share**: exported with `cosigner-cli export` as an `.mshare` file, sealed with a six-word passphrase. Fystack Recovery unlocks each file, combines the shares and checks the result against the wallet's public keys. One share alone cannot rebuild a key. _Diagram: Recovery sequence: generate an RSA key pair, export the Fystack share from the dashboard, export the cosigner share, then add, unlock, combine and verify the shares in Fystack Recovery_ ## Before you start Download the [latest Fystack Recovery release](https://github.com/fystack/cosigner-recovery/releases/latest) while you are still online, then move it to the offline machine. It is open source, so you can review and build it yourself. [Download Fystack Recovery](https://github.com/fystack/cosigner-recovery/releases/latest) [View on GitHub](https://github.com/fystack/cosigner-recovery) ## Step 1: Generate an RSA key pair The Fystack share is sealed to your RSA public key. Generate the key pair on the offline machine and keep the private key there. ```bash openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:4096 -out recovery.key openssl rsa -in recovery.key -pubout -out recovery.pub ``` Only `recovery.pub` leaves the offline machine. ## Step 2: Export the Fystack share Open the wallet in the dashboard and go to the **Signers** tab. The Fystack signer has an **Export Share** button. _Diagram: Wallet Signers tab showing the Fystack internal signer with an Export Share button and a server cosigner_ 1. Click **Export Share**. 2. Paste the contents of `recovery.pub` into **Recipient RSA public key (PEM)**. 3. Type the wallet name to confirm and tick the acknowledgement. 4. Click **Export Share** to download the `.enc` bundle. _Diagram: Export Key Share dialog with the recipient RSA public key, wallet name confirmation and acknowledgement checkbox_ Only the holder of the matching RSA private key can decrypt the bundle. ## Step 3: Export the cosigner share On the cosigner host, stop the cosigner and run `export`. It writes one `.mshare` per wallet and prints a recovery passphrase once. See [Operations](https://docs.fystack.io/cosigner/operations.md#recovery-export) for details. ```bash cosigner-cli stop cosigner-cli export --out-dir /secure/recovery cosigner-cli start ``` _Diagram: cosigner-cli export output listing the written .mshare files and the one-time recovery passphrase_ Each file is named `--.mshare`. Copy the file for the wallet you are recovering to the offline machine. > **Note:** The passphrase is shown only once and unlocks every file in the export. Store it separately from the files. ## Step 4: Add and unlock shares Open Fystack Recovery on the offline machine and click **Add share file**. _Diagram: Fystack Recovery step 1, Add and unlock shares, with no shares added yet_ Recovery supports both formats: - **RSA bundle** (`.enc`): unlocked with the RSA private key from Step 1. - **Passphrase** (`.mshare`): unlocked with the six-word passphrase from Step 3. Add every share you have. There is no threshold to enter: the counters show how many ECDSA and EdDSA shares are unlocked out of the wallet's participants. _Diagram: Recovery with the RSA bundle unlocked and the passphrase share waiting for its passphrase, 1 of 2 participants unlocked_ Enter the passphrase and click **Unlock**. When every share shows **Unlocked**, click **Continue**. _Diagram: Recovery with both shares unlocked, 2 of 2 participants for ECDSA and EdDSA_ For HD wallets, also add the child wallet list exported with the master share under **Child wallets** to recover every child wallet. ## Step 5: Recover Review the wallet ID and the share counts, then click **Recover keys**. _Diagram: Recover step showing the wallet ID and 2 ECDSA and 2 EdDSA shares ready to combine_ ## Step 6: Use the recovered keys Recovery combines the shares, then checks each key against the wallet's public key and test-signs with it. Both checks must pass. _Diagram: Recovered keys page showing the ECDSA key verified and test-signed with its Ethereum address, private key and public key, followed by the EdDSA key_ For each curve the result shows: - **ECDSA**: the Ethereum / EVM address, the private key (hex) and the compressed public key. - **EdDSA**: the Solana address, the private key and the public key. The private key stays hidden until you click **Reveal**. Use **Copy** or **Export...** to move it into the destination wallet, then click **Start over** to clear it from memory. ## Security checklist - Run Recovery on an air-gapped machine. Stay offline and never screenshot recovered keys. - Keep the RSA private key and the cosigner passphrase apart from the share files. - Move funds to a new wallet once recovered. The old wallet no longer has threshold protection. - Delete share files, the RSA private key and any exported keys when you are done.