> For the complete documentation index, see [llms.txt](https://docs.getblock.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.getblock.io/api-reference/sui-sui/signatureverificationservice-verifysignature-sui.md).

# SignatureVerificationService/VerifySignature - SUI

Verifies a `UserSignature` against a message. Sui supports multiple signature schemes including Ed25519, Secp256k1, Secp256r1, and zkLogin signatures (proofs over OAuth credentials). The verifier picks the correct scheme based on the signature bytes.

**Service**: `sui.rpc.v2.SignatureVerificationService`\
**Proto file**: [`sui/rpc/v2/signature_verification_service.proto`](https://github.com/MystenLabs/sui-apis/blob/main/proto/sui/rpc/v2/signature_verification_service.proto)\
**Full method path**: `sui.rpc.v2.SignatureVerificationService/VerifySignature`

## Request Fields

| Field     | Type            | Required | Description                                                                                                            |
| --------- | --------------- | -------- | ---------------------------------------------------------------------------------------------------------------------- |
| message   | string (base64) | Yes      | Base64-encoded message that was signed                                                                                 |
| signature | string (base64) | Yes      | Base64-encoded signature bytes (includes scheme byte)                                                                  |
| address   | Address         | No       | Expected signer address; if provided, verification additionally checks that the signature was produced by this address |

## Request Example

{% tabs %}
{% tab title="grpcurl" %}

```bash
# Clone the official proto files first (one-time setup):
#   git clone https://github.com/MystenLabs/sui-apis.git && cd sui-apis

grpcurl \
  -import-path proto \
  -proto sui/rpc/v2/signature_verification_service.proto \
  -H "x-grpc-web: 1" \
  -d '{
    "message": "SGVsbG8sIFN1aSE=",
    "signature": "ANQ7+Lr9X4eYRT5/A...",
    "address": "0xb871a42470b59c7184033a688f883cf24eb5e66eae1db62319bab27adb30b873"
}' \
  shared.eu-central-1.getblock.io:443/<ACCESS-TOKEN> \
  sui.rpc.v2.SignatureVerificationService/VerifySignature
```

{% endtab %}

{% tab title="TypeScript (@grpc/grpc-js)" %}

```typescript
import * as grpc from '@grpc/grpc-js';
import * as protoLoader from '@grpc/proto-loader';
import * as path from 'path';

const PROTO_PATH = path.join(__dirname, 'protos/proto/sui/rpc/v2/signature_verification_service.proto');
const ACCESS_TOKEN = '<ACCESS-TOKEN>';

const packageDef = protoLoader.loadSync(PROTO_PATH, {
    includeDirs: [path.join(__dirname, 'protos/proto')],
    keepCase: true, longs: String, enums: String, defaults: true,
});
const proto = grpc.loadPackageDefinition(packageDef) as any;
const ServiceClient = proto.sui.rpc.v2.SignatureVerificationService;

const metadata = new grpc.Metadata();
metadata.add('authorization', `Bearer ${ACCESS_TOKEN}`);

const client = new ServiceClient('shared.eu-central-1.getblock.io:443', grpc.credentials.createSsl());

const request = {
    "message": "SGVsbG8sIFN1aSE=",
    "signature": "ANQ7+Lr9X4eYRT5/A...",
    "address": "0xb871a42470b59c7184033a688f883cf24eb5e66eae1db62319bab27adb30b873"
};

client.VerifySignature(request, metadata, (err: any, response: any) => {
    if (err) {
        console.error('Error:', err);
        return;
    }
    console.log(JSON.stringify(response, null, 2));
});
```

{% endtab %}

{% tab title="Python (grpcio)" %}

```python
# First generate Python stubs from the proto files (one-time setup):
#   pip install grpcio grpcio-tools
#   python -m grpc_tools.protoc -I=proto --python_out=. --grpc_python_out=. \
#       proto/sui/rpc/v2/signature_verification_service.proto

import grpc
from sui.rpc.v2 import sui_rpc_v2_signature_verification_service_pb2, sui_rpc_v2_signature_verification_service_pb2_grpc
from google.protobuf.json_format import ParseDict, MessageToJson

ACCESS_TOKEN = '<ACCESS-TOKEN>'

channel = grpc.secure_channel('shared.eu-central-1.getblock.io:443', grpc.ssl_channel_credentials())
stub = sui_rpc_v2_signature_verification_service_pb2_grpc.SignatureVerificationServiceStub(channel)

metadata = [('authorization', f'Bearer {ACCESS_TOKEN}')]

# Build the request message from a dict via ParseDict for readability
request_data = {
    "message": "SGVsbG8sIFN1aSE=",
    "signature": "ANQ7+Lr9X4eYRT5/A...",
    "address": "0xb871a42470b59c7184033a688f883cf24eb5e66eae1db62319bab27adb30b873"
}
request = ParseDict(request_data, sui_rpc_v2_signature_verification_service_pb2.SignatureVerificationRequest())
# (Use the appropriate <Method>Request type — adjust as needed for the specific method.)

response = stub.VerifySignature(request, metadata=metadata)
print(response)
```

{% endtab %}

{% tab title="Rust (tonic)" %}

```rust
// Add to Cargo.toml:
//   tonic = "0.12"
//   prost = "0.13"
//   tokio = { version = "1", features = ["full"] }
// Plus a build.rs invoking tonic_build on the Sui proto files.

use tonic::{transport::Channel, Request};
use sui_rpc_v2::signature_verification_service_client::SignatureVerificationServiceClient;
// Plus the relevant <Method>Request type import from sui_rpc_v2.

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let channel = Channel::from_static("https://shared.eu-central-1.getblock.io").connect().await?;
    let mut client = SignatureVerificationServiceClient::with_interceptor(channel, |mut req: Request<()>| {
        req.metadata_mut().insert("authorization", "Bearer <ACCESS-TOKEN>".parse().unwrap());
        Ok(req)
    });

    let request_json = r#"{
    "message": "SGVsbG8sIFN1aSE=",
    "signature": "ANQ7+Lr9X4eYRT5/A...",
    "address": "0xb871a42470b59c7184033a688f883cf24eb5e66eae1db62319bab27adb30b873"
}"#;
    let request = Request::new(serde_json::from_str(request_json)?);

    let response = client.verify_signature(request).await?;
    println!("Response: {:?}", response.into_inner());
    Ok(())
}
```

{% endtab %}
{% endtabs %}

## Response Example

Responses are encoded in Protocol Buffers binary format on the wire. The example below shows the protobuf JSON encoding for readability.

{% code overflow="wrap" %}

```json
{
    "is_valid": true,
    "signer_address": "0xb871a42470b59c7184033a688f883cf24eb5e66eae1db62319bab27adb30b873",
    "scheme": "ED25519"
}
```

{% endcode %}

## Response Fields

| Field           | Type    | Description                                                                      |
| --------------- | ------- | -------------------------------------------------------------------------------- |
| is\_valid       | bool    | `true` if the signature is valid for the message                                 |
| signer\_address | Address | Address derived from the signature's public key                                  |
| scheme          | string  | Signature scheme — `ED25519`, `SECP256K1`, `SECP256R1`, `MULTISIG`, or `ZKLOGIN` |

## Use Cases

* Off-chain login flows that authenticate users by signature
* API gateways verifying signed requests without re-implementing Sui's signature schemes
* zkLogin integrations validating OAuth-backed signatures

## Error Handling

gRPC uses status codes rather than JSON-RPC numeric error codes. The most relevant for this method:

| Status Code         | Numeric | Cause                                                                                               |
| ------------------- | ------- | --------------------------------------------------------------------------------------------------- |
| UNAUTHENTICATED     | 16      | Missing or invalid `<ACCESS-TOKEN>` in the URL path                                                 |
| INVALID\_ARGUMENT   | 3       | Request fields are missing, malformed, or fail validation                                           |
| UNAVAILABLE         | 14      | Node is overloaded or temporarily unable to handle the request — retry with backoff                 |
| DEADLINE\_EXCEEDED  | 4       | Request did not complete within the timeout window                                                  |
| RESOURCE\_EXHAUSTED | 8       | Rate limit exceeded for your plan                                                                   |
| INVALID\_ARGUMENT   | 3       | Malformed message, signature, or address — or signature/address mismatch when `address` is provided |

## SDK Integration

{% tabs %}
{% tab title="@mysten/sui (TypeScript)" %}

```typescript
// The Mysten Labs TypeScript SDK provides higher-level wrappers around the
// gRPC API. Use @mysten/sui for typed client access:

import { SuiClient } from '@mysten/sui/client';

const client = new SuiClient({
    url: 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/'
});

// Refer to the @mysten/sui API reference for the typed wrapper of this method;
// raw gRPC call to sui.rpc.v2.SignatureVerificationService/VerifySignature is available as shown in the
// Request Example tabs above.
```

{% endtab %}

{% tab title="pysui (Python)" %}

```python
# pysui is the community-maintained Python SDK for Sui (Mysten Labs does not
# yet publish an official Python SDK). For raw gRPC access, use grpcio with
# the generated proto stubs as shown in the Request Example tabs above.

from pysui import SuiConfig, SyncClient

config = SuiConfig.user_config(
    rpc_url='https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/'
)
client = SyncClient(config)

# Consult pysui docs for the wrapper of SignatureVerificationService.VerifySignature.
```

{% endtab %}
{% endtabs %}