📒Blockchain Updates

Our API includes various endpoints that involve on-chain activities and updates, such as ownership verification and smart contract deployment. In order to provide smooth experience and maximum level of security, we employ cryptographic challenges and signatures tailored to each supported blockchain.

Account Creation

To create a new account for the customer and set it up for fund transfers with OffBlocks, we need to deploy a smart-contract account to the respective blockchain. The customer remains the ultimate owner of this account, and to manage funds for off-chain transactions on the user's behalf, we need them to sign a session key issued in the form of a cryptographic challenge. Similar to other endpoints, the challenge returned by the endpoint is a Base64-encoded string.

Create new customer account

post

/customers/{customerId}/accounts

Creates new account for the customer and generates a challenge to be signed in order to create a related blockchain account

Authorizations

AuthorizationstringRequired

Bearer authentication header of the form Bearer <token>.

Path parameters

customerIdstring · uuidRequired

Unique customer ID

Header parameters

SignaturestringRequired

HTTP message signature

Signature-InputstringRequired

HTTP message signature input

Idempotency-Keystring · uuidRequired

Idempotency key (UUID)

Content-DigeststringRequired

Content digest

Body

typestring · enumRequired

Type of the account

Possible values:

currenciesstring[]Required

Currencies of the account, at least one is required (ISO-4217)

Responses

201

Successful operation

application/json

Cryptographic challenge generated to be signed by owner's EOA private key according to chain-specific algorithm. Challenge is used for verifying ownership of the account and signing on-chain transactions such as creating a new account, authorising a recurring payment or setting up spending limits

idstring · uuidRequired

Unique account ID

customerIdstring · uuidRequired

Unique customer ID

chainIdstringOptional

Unique account ID in a form of a valid on-chain address. This would normally correspond to account's SCA address

Example: eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb

statusstring · enumRequired

Account status

Possible values:

typestring · enumRequired

Type of the account

Possible values:

currenciesstring[]Optional

Currencies of the account, at least one is required (ISO-4217)

createdAtstring · date-timeRequired

Date this account was created (ISO-8601)

updatedAtstring · date-timeRequired

Date this account was updated (ISO-8601)

challengestring · byteRequired

Base64 encoded message provided by this API for owner to sign

Example:

LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=

400

Invalid request

401

Not authorised

404

Customer not found

500

Internal error

post/customers/{customerId}/accounts

POST /v1/customers/{customerId}/accounts HTTP/1.1
Host: api.offblocks.xyz
Authorization: Bearer YOUR_SECRET_TOKEN
Signature: text
Signature-Input: text
Idempotency-Key: 123e4567-e89b-12d3-a456-426614174000
Content-Digest: text
Content-Type: application/json
Accept: */*
Content-Length: 45

{
  "type": "card_account",
  "currencies": [
    "text"
  ]
}

{
  "id": "123e4567-e89b-12d3-a456-426614174000",
  "customerId": "123e4567-e89b-12d3-a456-426614174000",
  "chainId": "eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb",
  "status": "initiating",
  "type": "card_account",
  "currencies": [
    "text"
  ],
  "createdAt": "2026-07-16T22:41:41.608Z",
  "updatedAt": "2026-07-16T22:41:41.608Z",
  "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0="
}

To submit a signed challenge, please use the corresponding endpoint.

Sign previously issued account challenge

post

/accounts/{accountId}/challenge/sign

Signs previously issued challenge to sign account creation or deletion transaction on-chain

Authorizations

AuthorizationstringRequired

Bearer authentication header of the form Bearer <token>.

Path parameters

accountIdstring · uuidRequired

Unique account ID

Header parameters

SignaturestringRequired

HTTP message signature

Signature-InputstringRequired

HTTP message signature input

Idempotency-Keystring · uuidRequired

Idempotency key (UUID)

Content-DigeststringRequired

Content digest

Body

Cryptographic signature generated using owner's EOA private key according to chain-specific algorithm. Signature is used for signing on-chain transactions such as creating a new account, authorising a recurring payment or setting up spending limits

ownerIdstringRequired

Unique signer account ID in a form of a valid on-chain address

Example: eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb

challengestring · byteRequired

Original base64 encoded challenge provided by this API for owner to sign

Example:

LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=

signaturestring · byteRequired

Base64 encoded signature

Example: IfvwaW1eCqLvQaK0/7YjvK8HBGHWHPclHHQWH4L+w6Q3CFS8CjSzq0h8G8AhzTGMc0xRrik3TyvrDm8t1JtL9Bw=

Responses

204

Successful operation

No content

400

Invalid request

401

Not authorised

404

Account not found

409

Challenge already signed

500

Internal error

post/accounts/{accountId}/challenge/sign

POST /v1/accounts/{accountId}/challenge/sign HTTP/1.1
Host: api.offblocks.xyz
Authorization: Bearer YOUR_SECRET_TOKEN
Signature: text
Signature-Input: text
Idempotency-Key: 123e4567-e89b-12d3-a456-426614174000
Content-Digest: text
Content-Type: application/json
Accept: */*
Content-Length: 415

{
  "ownerId": "eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb",
  "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=",
  "signature": "IfvwaW1eCqLvQaK0/7YjvK8HBGHWHPclHHQWH4L+w6Q3CFS8CjSzq0h8G8AhzTGMc0xRrik3TyvrDm8t1JtL9Bw="
}

No content

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.

Retrieve account challenge

get

/accounts/{accountId}/challenge

Retrieves challenge to sign account creation or deletion transaction on-chain. This operation invalidates any previously issued challenges for the account

Authorizations

AuthorizationstringRequired

Bearer authentication header of the form Bearer <token>.

Path parameters

accountIdstring · uuidRequired

Unique account ID

Header parameters

SignaturestringRequired

HTTP message signature

Signature-InputstringRequired

HTTP message signature input

Responses

200

Successful operation

application/json

challengestring · byteRequired

Base64 encoded message provided by this API for owner to sign

Example:

LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=

400

Invalid request

401

Not authorised

404

Account not found

500

Internal error

get/accounts/{accountId}/challenge

GET /v1/accounts/{accountId}/challenge HTTP/1.1
Host: api.offblocks.xyz
Authorization: Bearer YOUR_SECRET_TOKEN
Signature: text
Signature-Input: text
Accept: */*

{
  "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0="
}

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Last updated 2 years ago