chore: added code examples and fixed error response

pages/docs/ledger-live/exchange/card/_meta.js

@@ -1,5 +1,6 @@
 export default {
 	'providers-backend': "Backend",
 	'providers-liveapp': "LiveApp",
-	'providers-test-and-submit': "Test & Submit"
+	'providers-test-and-submit': "Test & Submit",
+	'code-examples': "Code Examples"
 }

pages/docs/ledger-live/exchange/card/code-examples.mdx

@@ -0,0 +1,9 @@
+import Zoom from 'react-medium-image-zoom'
+import 'react-medium-image-zoom/dist/styles.css'
+import { Tabs } from 'nextra/components'
+import { Callout } from 'nextra/components'
+import CodeExamples from '../../../../../public/exchange/import/code-examples.mdx'
+
+# Backend
+
+<CodeExamples />

pages/docs/ledger-live/exchange/card/providers-backend.mdx

@@ -127,6 +127,8 @@ Here is a little diagram to explain how the `payload` and the `signature` are ge
 - `payload`: the trade parameters are assembled in a [protobuf](https://developers.google.com/protocol-buffers) message. Then using the protobuf tools we do a [binary encoding](https://developers.google.com/protocol-buffers/docs/encoding) of the protobuf (Byte Array). Finally, with [base64Url encoding](https://en.wikipedia.org/wiki/Base64) we get the `payload` field.
 - `signature`: From the [base64Url](https://en.wikipedia.org/wiki/Base64) encoded payload of the previous [protobuf](https://developers.google.com/protocol-buffers) (Byte Array), we sign it with [ES256](https://ldapwiki.com/wiki/Wiki.jsp?page=ES256) and the provider's private key to get a Signature Byte Array. Finally, with [base64Url encoding](https://en.wikipedia.org/wiki/Base64) we get the `signature` field ([more details](#jws-signature)).
 
+If you need help with the signing process, please refer to our code [examples](code-examples.mdx).
+
 ### Signature usage
 
 - Payload and Signature  

pages/docs/ledger-live/exchange/sell/_meta.js

@@ -1,5 +1,6 @@
 export default {
 	'providers-backend': "Backend",
 	'providers-liveapp': "LiveApp",
-	'providers-test-and-submit': "Test & Submit"
+	'providers-test-and-submit': "Test & Submit",
+	'code-examples': "Code Examples"
 }

pages/docs/ledger-live/exchange/sell/code-examples.mdx

@@ -0,0 +1,9 @@
+import Zoom from 'react-medium-image-zoom'
+import 'react-medium-image-zoom/dist/styles.css'
+import { Tabs } from 'nextra/components'
+import { Callout } from 'nextra/components'
+import CodeExamples from '../../../../../public/exchange/import/code-examples.mdx'
+
+# Backend
+
+<CodeExamples />

pages/docs/ledger-live/exchange/sell/providers-backend.mdx

@@ -130,6 +130,8 @@ Here is a little diagram to explain how the `payload` and the `signature` are ge
 - `payload`: the trade parameters are assembled in a [protobuf](https://developers.google.com/protocol-buffers) message. Then using the protobuf tools we do a [binary encoding](https://developers.google.com/protocol-buffers/docs/encoding) of the protobuf (Byte Array). Finally, with [base64Url encoding](https://en.wikipedia.org/wiki/Base64) we get the `payload` field.
 - `signature`: From the [base64Url encoding](https://en.wikipedia.org/wiki/Base64) encoded payload of the previous [protobuf](https://developers.google.com/protocol-buffers) (Byte Array), we sign it with [ES256](https://ldapwiki.com/wiki/Wiki.jsp?page=ES256) and the provider's private key to get a Signature Byte Array. Finally, with [base64Url encoding](https://en.wikipedia.org/wiki/Base64) we get the `signature` field ([more details](#jws-signature)).
 
+If you need help with the signing process, please refer to our code [examples](code-examples.mdx).
+
 ### Signature usage
 
 - Payload and Signature  

public/exchange/import/code-examples.mdx

@@ -0,0 +1,100 @@
+# Java
+```java
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import java.security.*;
+import java.util.Base64;
+
+public class App {
+
+    static {
+        Security.addProvider(new BouncyCastleProvider());
+    }
+
+    public static void main(String[] args) throws Exception {
+        byte[] payloadBytes = response.toByteArray();
+        String payload = Base64.getUrlEncoder().withoutPadding().encodeToString(payloadBytes);
+        PrivateKey key = getPrivateKeyFromPEMFile("<path to your private key>");
+        byte[] sign = signPayload(("." + payload).getBytes(), key);
+        String signature = Base64.getUrlEncoder().withoutPadding().encodeToString(sign);
+    }
+
+    public static byte[] signPayload(byte[] payloadBytes, PrivateKey privateKey) throws Exception {
+        Signature signer = Signature.getInstance("SHA256withPlain-ECDSA", "BC");
+        signer.initSign(privateKey);
+        signer.update(payloadBytes);
+        return signer.sign();
+    }
+}
+```
+
+# Python
+```python
+import base64
+import os
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives import hashes
+from google.protobuf import message
+import sell_pb2  # Import the generated protobuf classes
+from cryptography.hazmat.primitives.asymmetric.utils import decode_dss_signature
+
+
+def base64_url_encode(data):
+    return base64.urlsafe_b64encode(data).rstrip(b'=').decode('utf-8')
+
+
+def sign_payload(payload, private_key):
+    # Sign the payload using ECDSA with SHA-256
+    der_signature = private_key.sign(
+        payload,
+        ec.ECDSA(hashes.SHA256())
+    )
+    # Decode the DER-encoded signature to get r and s
+    r, s = decode_dss_signature(der_signature)
+    # Convert r and s to bytes
+    r_bytes = r.to_bytes(32, byteorder='big')
+    s_bytes = s.to_bytes(32, byteorder='big')
+    return r_bytes + s_bytes
+
+
+if __name__ == "__main__":
+    payload = response.SerializeToString()
+    encoded_payload = base64_url_encode(payload)
+    # Sign the payload
+    signature = sign_payload(("." + encoded_payload).encode('utf-8'), private_key)
+    # Base64 URL encode the signature
+    encoded_signature = base64_url_encode(signature)
+    provider_sig = {
+        "payload": encoded_payload,
+        "signature": encoded_signature
+    }
+```
+
+# typescript
+```typescript
+const base64EncodedPayload = base64url.encode(
+   Buffer.from(uInt8ArrayEncodedPayload), // this is encoded payload using protobuf
+);
+
+function signProviderSignaturePayload(base64EncodedPayload: string): string {
+    const ec = new EC('secp256k1');
+    const keyPair = ec.keyFromPrivate(
+      <PRIVATE_KEY_GOES_HERE>,
+      'hex',
+    );
+    const hashedMessage = crypto
+      .createHash('sha256')
+      .update(`.${base64EncodedPayload}`)
+      .digest();
+    const signature = keyPair.sign(hashedMessage);
+
+    const r = signature.r.toString('hex').padStart(64, '0');
+    const s = signature.s.toString('hex').padStart(64, '0');
+
+    const signatureBuffer = Buffer.from(r + s, 'hex');
+    const signatureBase64 = signatureBuffer.toString('base64url');
+
+    return signatureBase64;
+}
+```

public/exchange/openapi/card-provider-openapi.yml

@@ -233,6 +233,9 @@ components:
           description: Payload signed in JWS format.
     ErrorPayload:
       type: object
+      required:
+        - messageKey
+        - message
       properties:
         messageKey:
           type: string

public/exchange/openapi/sell-provider-openapi.yml

@@ -72,7 +72,7 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/ProviderServerError'
+                $ref: '#/components/schemas/ErrorPayload'
               example:
                 code: 400
                 message: Server isn't able to handle the request because of whatever.
@@ -161,13 +161,13 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/ProviderServerError'
+                $ref: '#/components/schemas/ErrorPayload'
         default:
           description: Error sent by the provider
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/ProviderServerError'
+                $ref: '#/components/schemas/ErrorPayload'
   /crypto-currencies:
     get:
       operationId: getCrypto-currencies
@@ -201,7 +201,7 @@ paths:
           content:
             application/json:
               schema:
-                $ref: '#/components/schemas/ProviderServerError'
+                $ref: '#/components/schemas/ErrorPayload'
               example:
                 code: 42
                 message: Server isn't able to handle the request because of whatever.
@@ -512,17 +512,6 @@ components:
         expiry:
           type: string
           description: Quote expiration timestamp
-    ProviderServerError:
-      required:
-        - code
-        - message
-      type: object
-      properties:
-        code:
-          type: integer
-          format: int32
-        message:
-          type: string
     Sepa:
       type: object
     Token:
@@ -614,6 +603,9 @@ components:
           description: Payload signed in JWS format.
     ErrorPayload:
       type: object
+      required:
+        - message
+        - messageKey
       properties:
         messageKey:
           type: string