> For the complete documentation index, see [llms.txt](https://shinkalabs.gitbook.io/hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://shinkalabs.gitbook.io/hub/andromeda/reference/chains-curves.md).

# Chains & curves

A dWallet is keyed on a curve. Pick the curve that matches the chain you will sign for. The Ika threshold-signing layer supports four curves; Andromeda exposes all of them through one REST surface.

| Curve         | Chains and use cases                                                                                     |
| ------------- | -------------------------------------------------------------------------------------------------------- |
| **Ed25519**   | Solana, NEAR, Aptos, Cosmos (ed25519 accounts), Substrate (ed25519 accounts)                             |
| **SECP256K1** | EVM chains (Ethereum, L2s, sidechains), Bitcoin, Cosmos (secp256k1 accounts), Substrate (ECDSA accounts) |
| **SECP256R1** | NIST P-256 use cases; passkeys / WebAuthn credentials                                                    |
| **Ristretto** | Substrate / Polkadot sr25519 family                                                                      |

## Notes per ecosystem

* **EVM**: SECP256K1. You get a secp256k1 signature; build the transaction with your usual EVM library and broadcast.
* **Bitcoin**: SECP256K1. For proving ownership of an existing Bitcoin wallet during discovery, BIP-137 message signatures are used.
* **Solana**: Ed25519.
* **NEAR / Aptos**: Ed25519. Discovery uses each chain's signed-message convention (NEP-413 for NEAR, AIP-62 for Aptos).
* **Cosmos**: either Ed25519 or SECP256K1 depending on the account type. Discovery uses ADR-036.
* **Substrate / Polkadot**: natively supports ed25519, ECDSA (secp256k1), and sr25519. On Andromeda, dWallets can use Ed25519 or SECP256K1; sr25519 (Ristretto) is supported for signing but not for on-chain recovery validation. See [Recovery schemes](/hub/andromeda/reference/recovery-schemes.md).

## On-chain recovery is narrower than signing

Signing supports all four curves. The on-chain recovery and policy programs only validate signatures for which a Solana runtime precompile exists: Ed25519, Secp256k1, Secp256r1, and full WebAuthn (quorum members only). There is no on-chain validation for sr25519, Ristretto, or pure Bitcoin Taproot, by design (no off-chain attestor). Substrate users enroll recovery owners with Ed25519 or Secp256k1; Bitcoin users prove ownership via BIP-137 (Secp256k1). See [Zero attestor](/hub/andromeda/concepts/zero-attestor.md) and [Known limitations](/hub/andromeda/reference/limitations.md).


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