Issue with Sending Requests to SageMaker Endpoint using Jmeter - Invalid Signature

I am reaching out to report an issue I encountered while using the JMeter tool to send requests to a SageMaker endpoint. Despite carefully filling in all the necessary information, I am consistently receiving the following error message

I have attached the code snippet below that I used to generate the authentication headers for your reference:

import javax.crypto.Mac import javax.crypto.spec.SecretKeySpec import java.security.InvalidKeyException import java.security.MessageDigest import java.text.SimpleDateFormat import java.util.Date import java.util.TimeZone import java.net.URLDecoder import java.net.URLEncoder import java.util.LinkedHashMap import java.util.Map import java.util.TreeMap import java.io.UnsupportedEncodingException

// Defined in User Defined Variables def access_key = vars.get("aws_access_key") def secret_key = vars.get("aws_secret_key") def service = vars.get("aws_service_name") def host = vars.get("aws_host") def region = vars.get("aws_region")

log.info("Access Key: " + access_key)

// Obtain data from the HTTP Request Sampler def method = sampler.getMethod() def url = sampler.getUrl() def req_path = url.getPath() def req_query_string = orderQuery(url) def request_parameters = ''

sampler.getArguments().each { arg -> request_parameters = arg.getStringValue().substring(1) }

// Create the variable x-amz-date def now = new Date() def amzFormat = new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'") def stampFormat = new SimpleDateFormat("yyyyMMdd") amzFormat.setTimeZone(TimeZone.getTimeZone("UTC")) // server timezone def amzDate = amzFormat.format(now) def dateStamp = stampFormat.format(now) vars.put("x_amz_date", amzDate)

// Create a Canonical Request def canonical_uri = req_path def canonical_querystring = req_query_string def canonical_headers = "host:" + host + "\n" + "x-amz-date:" + amzDate + "\n" def signed_headers = "host;x-amz-date" def payload_hash = getHexDigest(request_parameters) def canonical_request = method + "\n" + canonical_uri + "\n" + canonical_querystring + "\n" + canonical_headers + "\n" + signed_headers + "\n" + payload_hash

log.info("canonical_request: " + canonical_request)

// Create the String to Sign def algorithm = "AWS4-HMAC-SHA256" def credential_scope = dateStamp + "/" + region + "/" + service + "/" + "aws4_request" def hash_canonical_request = getHexDigest(canonical_request) def string_to_sign = algorithm + "\n" + amzDate + "\n" + credential_scope + "\n" + hash_canonical_request log.info("string_to_sign: " + string_to_sign)

// Calculate the Signing Key def signing_key = getSignatureKey(secret_key, dateStamp, region, service) def signature = hmac_sha256Hex(signing_key, string_to_sign)

// Add Signing information to Variable def authorization_header = algorithm + " " + "Credential=" + access_key + "/" + credential_scope + ", " + "SignedHeaders=" + signed_headers + ", " + "Signature=" + signature vars.put("aws_authorization", authorization_header)

def hmac_sha256(secretKey, data) { Mac mac = Mac.getInstance("HmacSHA256") SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey, "HmacSHA256") mac.init(secretKeySpec) byte[] digest = mac.doFinal(data.getBytes()) return digest }

def hmac_sha256Hex(secretKey, data) { def result = hmac_sha256(secretKey, data) return result.encodeHex() }

def getSignatureKey(key, dateStamp, regionName, serviceName) { def kDate = hmac_sha256(("AWS4" + key).getBytes(), dateStamp) def kRegion = hmac_sha256(kDate, regionName) def kService = hmac_sha256(kRegion, serviceName) def kSigning = hmac_sha256(kService, "aws4_request") return kSigning }

def getHexDigest(text) { def md = MessageDigest.getInstance("SHA-256") md.update(text.getBytes()) return md.digest().encodeHex() }

public static String orderQuery(URL url) throws UnsupportedEncodingException { def orderQueryString = "" Map<String, String> queryPairs = new LinkedHashMap<>() String queryParams = url.getQuery()

if (queryParams != null) {
    String[] pairs = queryParams.split("&")

    for (String pair : pairs) {
        int idx = pair.indexOf("=")
        queryPairs.put(URLDecoder.decode(pair.substring(0, idx), "UTF-8"), URLDecoder.decode(pair.substring(idx + 1), "UTF-8"))
    }
    def orderQueryArray = new TreeMap<>(queryPairs)
    orderQueryString = urlEncodeUTF8(orderQueryArray)
}
return orderQueryString

}

public static String urlEncodeUTF8(String s) { try { return URLEncoder.encode(s, "UTF-8") } catch (UnsupportedEncodingException e) { throw new UnsupportedOperationException(e) } }

public static String urlEncodeUTF8(Map<?, ?> map) { StringBuilder sb = new StringBuilder() for (Map.Entry<?, ?> entry : map.entrySet()) { if (sb.length() > 0) { sb.append("&") } sb.append(String.format("%s=%s", urlEncodeUTF8(entry.getKey().toString()), urlEncodeUTF8(entry.getValue().toString()) )) } return sb.toString() }

log.info("req_path: " + req_path) req_query_string = orderQuery(url) log.info("req_query_string: " + req_query_string) log.info("host: " + host) log.info("amzDate: " + amzDate)

I have taken care to ensure that all the necessary variables, such as the AWS Access Key, AWS Secret Access Key, service name, host, and region, are correctly provided in the JMeter test plan. However, despite these efforts, I am still facing a signature mismatch error.