Amazon Product Advertising API Developer's Manual page 67

Product Advertising API Developer Guide
private static final String HMAC_SHA256_ALGORITHM = "HmacSHA256";
private static final String REQUEST_URI = "/onca/xml";
private static final String REQUEST_METHOD = "GET";
private String endpoint = "webservices.amazon.com"; // must be lowercase
private String awsAccessKeyId = "YOUR AWS ACCESS KEY";
private String awsSecretKey = "YOUR AWS SECRET KEY";
private SecretKeySpec secretKeySpec = null;
private Mac mac = null;
public SignedRequestsHelper() {
byte[] secretyKeyBytes = awsSecretKey.getBytes(UTF8_CHARSET);
secretKeySpec =
new SecretKeySpec(secretyKeyBytes, HMAC_SHA256_ALGORITHM);
mac = Mac.getInstance(HMAC_SHA256_ALGORITHM);
mac.init(secretKeySpec);
}
public String sign(Map<String, String> params) {
params.put("AWSAccessKeyId", awsAccessKeyId);
params.put("Timestamp", timestamp());
SortedMap<String, String> sortedParamMap =
new TreeMap<String, String>(params);
String canonicalQS = canonicalize(sortedParamMap);
String toSign =
REQUEST_METHOD + "\n"
+ endpoint + "\n"
+ REQUEST_URI + "\n"
+ canonicalQS;
String hmac = hmac(toSign);
String sig = percentEncodeRfc3986(hmac);
String url = "http://" + endpoint + REQUEST_URI + "?" +
canonicalQS + "&Signature=" + sig;
return url;
}
private String hmac(String stringToSign) {
String signature = null;
byte[] data;
byte[] rawHmac;
try {
data = stringToSign.getBytes(UTF8_CHARSET);
rawHmac = mac.doFinal(data);
Base64 encoder = new Base64();
signature = new String(encoder.encode(rawHmac));
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(UTF8_CHARSET + " is unsupported!", e);
}
return signature;
}
private String timestamp() {
String timestamp = null;
Calendar cal = Calendar.getInstance();
Request Authentication
API Version 2011-08-01
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