shadow-signers: support for EVM #1474

guilleasz-crossmint · 2025-10-29T18:31:40Z

Description

Support EVM Shadow Signers in SDK

How it works

We generate a P-256 keypair and return a delegated signer: evm-p256-keypair with publicKey as base64.
Signing uses a storage callback that produces Stubbed WebAuthn-compatible signatures.

Test plan

Manual tested shadow signers with EVM

Package updates

- Add OnCreateConfig<C> type to wallets SDK types - Update WalletArgsFor<C> to include optional onCreateConfig field - Modify WalletFactory.createWallet() to use onCreateConfig admin signer when provided - Update validateExistingWalletConfig() to validate onCreateConfig parameters - Add validateSignerCanUseWallet() helper to ensure signer can use wallet - Add getSignerLocator() helper for determining signer locators - Remove server-side restriction from getWallet() method - Add comprehensive tests for onCreateConfig functionality - Update React Base SDK to export OnCreateConfig and support getWallet - Implement getWallet() in CrossmintWalletBaseProvider - Update getOrCreateWallet() to pass through onCreateConfig - Export OnCreateConfig type from React UI SDK This allows delegated signers to use the SDK by separating the concept of admin signer (who creates/owns the wallet) from usage signer (who interacts with it). Co-Authored-By: Guille <guille.a@paella.dev>

- Export OnCreateConfig from wallets SDK index - Inline chainType logic in CrossmintWalletBaseProvider instead of accessing private method Co-Authored-By: Guille <guille.a@paella.dev>

Breaking changes: - Remove delegatedSigners field from WalletArgsFor type - Remove delegatedSigners field from CreateOnLogin type - delegatedSigners now ONLY exist within onCreateConfig When onCreateConfig is provided: - args.signer = the signer that will USE the wallet (can be admin or delegated) - onCreateConfig.adminSigner = the admin who OWNS the wallet (only for creation) - onCreateConfig.delegatedSigners = delegated signers (only for creation) When onCreateConfig is NOT provided (backward compat): - args.signer acts as BOTH the admin and usage signer Updated: - WalletFactory validation logic to handle both cases - React providers to not pass delegatedSigners - Tests to only use onCreateConfig for delegated signers Co-Authored-By: Guille <guille.a@paella.dev>

- Created WalletCreateArgs type that extends WalletArgsFor with required onCreateConfig - Updated getOrCreateWallet and createWallet to use WalletCreateArgs - Updated CreateOnLogin type to use WalletCreateArgs - Made onCreateConfig optional in WalletArgsFor for getWallet use cases - args.signer is now always the usage signer, not the admin signer Co-Authored-By: Guille <guille.a@paella.dev>

Co-Authored-By: Guille <guille.a@paella.dev>

- Updated smart-wallet/next, quickstart-devkit, and expo apps - All createOnLogin usages now include onCreateConfig with adminSigner - Delegated signers moved from top-level to onCreateConfig Co-Authored-By: Guille <guille.a@paella.dev>

- Create tempArgs to capture mutation from mutateSignerFromCustomAuth - Reassign expectedAdminSigner from mutated tempArgs.signer - Ensures external wallet signer reassignment is captured correctly Co-Authored-By: Guille <guille.a@paella.dev>

- Create tempArgs to capture mutation from mutateSignerFromCustomAuth - Reassign adminSignerConfig from mutated tempArgs.signer - Ensures external wallet signer reassignment works correctly Co-Authored-By: Guille <guille.a@paella.dev>

- Add shadowSigner option to WalletOptions type - Create shadow-signer.ts utility for generating device-bound keypairs - Automatically generate shadow signers during wallet creation (client-side only) - Store shadow signer metadata in localStorage - Pass shadow signer configuration through React providers - Support ed25519 for Solana/Stellar and p256 passkeys for EVM chains - Gracefully handle shadow signer creation failures Co-Authored-By: Guille <guille.a@paella.dev>

Co-Authored-By: Guille <guille.a@paella.dev>

- Create SmartWalletConfig type to properly type wallet.config - Replace all 'as any' casts with SmartWalletConfig type - Improve error message clarity by avoiding 'args' in developer-facing text - Addresses PR feedback from Alberto Co-Authored-By: Guille <guille.a@paella.dev>

Co-Authored-By: Guille <guille.a@paella.dev>

…e' into guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

changeset-bot · 2025-10-29T18:31:43Z

🦋 Changeset detected

Latest commit: 7e6c42e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 18 packages

Name	Type
@crossmint/wallets-sdk	Minor
@crossmint/client-sdk-react-native-ui	Patch
@crossmint/common-sdk-base	Patch
expo-demo	Patch
@crossmint/client-sdk-react-base	Patch
@crossmint/client-sdk-react-ui	Patch
@crossmint/client-sdk-auth	Patch
@crossmint/client-sdk-base	Patch
@crossmint/client-sdk-verifiable-credentials	Patch
@crossmint/client-sdk-smart-wallet	Patch
@crossmint/client-sdk-walletconnect	Patch
@crossmint/common-sdk-auth	Patch
@crossmint/server-sdk	Patch
@crossmint/auth-ssr-nextjs-demo	Patch
@crossmint/client-sdk-nextjs-starter	Patch
@crossmint/wallets-quickstart-devkit	Patch
@crossmint/client-sdk-smart-wallet-next-starter	Patch
crossmint-auth-node	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

vercel · 2025-10-29T18:31:45Z

The latest updates on your projects. Learn more about Vercel for GitHub.

1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
smart-wallet-auth-demo	Ignored			Nov 26, 2025 5:23pm

…e' into guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

…guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

…hadow-signers-in-sdk

packages/wallets/src/signers/shadow-signer/shadow-signer-storage-browser.ts

packages/wallets/src/signers/shadow-signer/shadow-signer.ts

alberto-crossmint · 2025-11-26T14:36:19Z

packages/wallets/src/signers/shadow-signer/shadow-signer.ts

    }

-    hasShadowSigner(): this is { signer: ExternalWalletSigner<C> } {
+    hasShadowSigner(): this is { signer: S } {


I feel this is a bit confusing! A Shadow Signer gets casted to a subtype so there's an effective isomorphism between this and this.signer. What are the situations in which ShadowSigner.hasShadowSigner() is false. Wouldn't it fit better in an <ncs>.shadowSigner: ShadowSigner | null schema and if it exists we assume it "hasShadowSigner"?

Not saying this is wrong! Just to understand the motivation

The ShadowSigner instance is the one that initializes the signer when the wallet has a shadow signer. if we move that logic up to the ncs wallet we would need to move the shadow signer retrieval logic to each of this signers, this keeps it simpler by making all the other signers to have a shadowSigner instance which confirms if the wallet has or has not a shadow signer attached to it

alberto-crossmint · 2025-11-26T14:42:02Z

packages/wallets/src/signers/p256-keypair.ts

+    type = "p256-keypair" as const;
+    private _address: string;
+    private _locator: string;
+    private onSignTransaction: (publicKeyBase64: string, data: Uint8Array) => Promise<Uint8Array>;


Why do we need the publicKey as an input in this callback! Isn't it kept as an attribute of the class? Isn't it the value in _address?

Yes but onSignTransaction is defined as a config passed in the constructor, when defined it doesn't have access to this this. Check packages/wallets/src/signers/shadow-signer/evm-shadow-signer.ts:22

alberto-crossmint · 2025-11-26T14:54:30Z

packages/wallets/src/signers/evm-external-wallet.ts

+    constructor(
+        config: ExternalWalletInternalSignerConfig<EVMChain>,
+        walletAddress?: string,
+        shadowSignerEnabled?: boolean,


Can't we know this by checking if this.shadowSigner is not nullish?

shadowSignerEnabled comes from the wallets config from the args. It could happen that a wallet was created with a shadow signer, but now the client is disabling its use through the config

devin-ai-integration bot and others added 30 commits October 14, 2025 09:10

fix: export OnCreateConfig and fix getChainType access

8a5417a

- Export OnCreateConfig from wallets SDK index - Inline chainType logic in CrossmintWalletBaseProvider instead of accessing private method Co-Authored-By: Guille <guille.a@paella.dev>

chore: fix lint issues

c675932

Co-Authored-By: Guille <guille.a@paella.dev>

chore: update demo apps to use onCreateConfig

b642c2c

- Updated smart-wallet/next, quickstart-devkit, and expo apps - All createOnLogin usages now include onCreateConfig with adminSigner - Delegated signers moved from top-level to onCreateConfig Co-Authored-By: Guille <guille.a@paella.dev>

remove unnecesary type

1be9a9f

reuse common functionality from get and create

cfde33f

remove redundant comments

d59062a

fix tsc issue

c1ea37e

fix linter

6b8b3f3

added client side specific get wallet

3e6d5c2

fix signers and transactions

133dc92

fix delegated signer

5bd3ce4

remove redundant check

34f6f16

fix unit test

e0397c1

make oncreateconfig optional

9276bcf

remove unnecesary format changes

f890560

unify getWallet functionality

b04e71d

remove admin from name

43c64d8

fix react provider

77faeca

remove unnecessary types

6891aa5

remove optional param

ee8195b

fix: remove unused @ts-expect-error directive

1b0eba3

Co-Authored-By: Guille <guille.a@paella.dev>

fix: format error message to meet line length requirements

05fbb32

Co-Authored-By: Guille <guille.a@paella.dev>

refactor: remove Flow-specific check, let API handle incompatible chains

75a3e8f

Co-Authored-By: Guille <guille.a@paella.dev>

guilleasz-crossmint added 4 commits October 29, 2025 17:20

fix imports

e2669a0

Merge branch 'guillea/wal-7064-support-shadow-signers-for-react-nativ…

42c359b

…e' into guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

fix merge conflicts

4cf0b97

fix signer

2111f54

guilleasz-crossmint added 3 commits October 30, 2025 13:09

applied comments

15ea8ed

avoid injectin javascript

6b6d371

Merge branch 'guillea/wal-7064-support-shadow-signers-for-react-nativ…

cf3a19d

…e' into guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

guilleasz-crossmint force-pushed the guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk branch from e867852 to 5faf63b Compare October 30, 2025 15:27

Merge branch 'wallets-v1' of github.com:Crossmint/crossmint-sdk into …

2af0201

…guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk

guilleasz-crossmint force-pushed the guillea/wal-7240-add-support-for-evm-shadow-signers-in-sdk branch from 5faf63b to 2af0201 Compare October 30, 2025 15:28

guilleasz-crossmint added 8 commits October 30, 2025 16:35

don't make publicKeyBase64 optional

2ce1972

add changeset

35595aa

add device signer to evm

7368af6

add shadow signer to locator

dabde79

fix passkey creation

6fbf44b

Merge branch 'wallets-v1' into guillea/wal-7240-add-support-for-evm-s…

a23e334

…hadow-signers-in-sdk

fix passkeys

1757b14

Merge branch 'wallets-v1' into guillea/wal-7240-add-support-for-evm-s…

f6dd7d3

…hadow-signers-in-sdk