# Fireblock API integration in Java

**URL:** <https://community.fireblocks.com/t/fireblock-api-integration-in-java/1165>\
**Category:** Support\
**Created:** [July 4, 2024, 7:27am UTC](https://community.fireblocks.com/t/fireblock-api-integration-in-java/1165 "2024-07-04T07:27:55Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rajeev](https://avatars.discourse-cdn.com/v4/letter/r/ec9cab/32.png) [@Rajeev](https://community.fireblocks.com/u/Rajeev)\
**Post date:** [July 4, 2024, 7:27am UTC](https://community.fireblocks.com/t/fireblock-api-integration-in-java/1165/1 "2024-07-04T07:27:55Z")

</div>

I am trying to integrate fireblock APIs in my application. I am always getting 401 unauthorized: invalid signature error. Attaching the code for reference. Please check and let me know if I am doing anything wrong here.

```
@Value("${fireblocks.api.key}")
private String apiKey;

@Value("${fireblocks.privateKey.path}")
private String privateKeyPath;

private static final String FIREBLOCKS_API_URL = "https://sandbox-api.fireblocks.io/v1";

```

public String generateJWT() throws Exception {  
PrivateKey privateKey = getPrivateKey(privateKeyPath);  
long nowMillis = System.currentTimeMillis();  
long expMillis = nowMillis + 60000; // 1 minute expiration  
Date now = new Date(nowMillis);  
Date exp = new Date(expMillis);  
String token = Jwts.builder()  
.setIssuedAt(now)  
.setExpiration(exp)  
.setIssuer(apiKey)  
.signWith(privateKey, SignatureAlgorithm.RS256)  
.compact();

```
    return token;
}

private static PrivateKey getPrivateKey(String privateKeyPath) throws Exception {
    String privateKeyPEM = readPrivateKeyPEM(privateKeyPath);
    byte[] privateKeyBytes = decodePEM(privateKeyPEM);
    PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    return keyFactory.generatePrivate(keySpec);
}

private static String readPrivateKeyPEM(String privateKeyPath) throws Exception {
    try (FileReader reader = new FileReader(privateKeyPath)) {
        StringBuilder sb = new StringBuilder();
        int ch;
        while ((ch = reader.read()) != -1) {
            sb.append((char) ch);
        }
        return sb.toString();
    }
}

private static byte[] decodePEM(String pem) {
    // Strip out PEM header/footer and decode base64
    String privateKeyPEM = pem
            .replace("-----BEGIN PRIVATE KEY-----", "")
            .replace("-----END PRIVATE KEY-----", "")
            .replaceAll("\\s+", "");
    return Base64.getDecoder().decode(privateKeyPEM);
}

public String callFireblocksApi(String jwtToken) throws IOException {
    String url = FIREBLOCKS_API_URL + "/transactions"; // Adjust this endpoint as needed

    Request request = new Request.Builder()
            .url(url)
            .addHeader("X-API-Key", apiKey)
            .addHeader("Authorization", "Bearer " + generateJWT())
            .build();

    try (Response response = httpClient.newCall(request).execute()) {
        if (!response.isSuccessful()) {
            throw new IOException("Unexpected code " + response);
        }

        return response.body().string();
    }
}

```