πŸ“²Sign in With X

This functionality is currently only supported on EVM networks and is 100% compliant with EIP-4361 (Sign in With Ethereum). We will be adding support for more networks soon.

To verify a customer's externally-owned account ownership, we require a challenge to be signed with the private key. This mechanism is outlined in CAIP-122, originally known as "Sign in With Ethereum" (SIWE) but expanded to support other blockchains. When a new customer object is created in our system, we generate a challenge following the standardised structure, expecting it to be signed and verified before proceeding with user onboarding. The challenge returned by the endpoint is a Base64-encoded string.

When a new user is created on supported chains, you will receive a Base64 encoded challenge, which resembles the following:

api.sandbox.offblocks.xyz wants you to sign in with your Ethereum account:
0x43158f45b5EbD7b1179130130DF00393928C2691

OffBlocks wants to verify ownership of your wallet. By connecting your wallet and using OffBlocks, you agree to our Terms of services and Privacy Policy

URI: https://api.sandbox.offblocks.xyz
Version: 1
Chain ID: 300
Nonce: 5ufoiEqDaFvmfo78
Issued At: 2024-01-17T18:21:53Z

In order to proceed with ownership verification, your customer needs to sign this challenge with their private key. Please, follow SIWE documentation to learn more about signing SIWE challenges using community supported libraries. For testing purposes, you can use MyCrypto signing tools to sign a challenge for test accounts.

If everything was successful, you will have a HEX-formatted signature ready to be submitted to our API. For example, if using MyCrypto, it will produce a following message for the above challenge:

{
  "address": "0x43158f45b5EbD7b1179130130DF00393928C2691",
  "msg": "api.sandbox.offblocks.xyz wants you to sign in with your Ethereum account:\n0x43158f45b5EbD7b1179130130DF00393928C2691\n\nOffBlocks wants to verify ownership of your wallet. By connecting your wallet and using OffBlocks, you agree to our Terms of services and Privacy Policy\n\nURI: https://api.sandbox.offblocks.xyz\nVersion: 1\nChain ID: 300\nNonce: 5ufoiEqDaFvmfo78\nIssued At: 2024-01-17T18:21:53Z",
  "sig": "0xd2472857a11a29b612fda39b3a381cc88a8e6d085333cb7e2536ea38e71664be5e88ada8f5de966eff4f7c9cf59429b9a24814d878e779db34b612d4091c26ba1c",
  "version": "2"
}

To submit a signed challenge, please encode a HEX signature as Base64 string and send it using the corresponding endpoint.

If, for any reason, the original challenge is lost or cannot be signed immediately, you can fetch it again using a dedicated endpoint. If we encounter an error during signature validation via /sign endpoint, a new challenge will be issued for you to retrieve.

We enforce a 1 hour expiration window via our API for all issued challenges for security purposes. If a challenge hasn't been signed within 1 hour from issue, we will generate a new one and make it available through this endpoint.

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