Javaにおける署名計算のためのサンプルコード

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以下のJavaコードサンプルは、署名(バージョン2)の計算方法を例示しています。このサンプルはbase64エンコード用に正規化されたタグを作成し、署名を生成するためにHMACエンコーディングを行うためのコードとなります。

package com.amazon.associates.sample;

import java.io.UnsupportedEncodingException;

import java.net.URLDecoder;
import java.net.URLEncoder;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import java.text.DateFormat;
import java.text.SimpleDateFormat;

import java.util.Calendar;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TimeZone;
import java.util.TreeMap;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class SignedRequestsHelper {
private static final String UTF8_CHARSET = "UTF-8";
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 = "ecs.amazonaws.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();
DateFormat dfm = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
dfm.setTimeZone(TimeZone.getTimeZone("GMT"));
timestamp = dfm.format(cal.getTime());
return timestamp;
}

private String canonicalize(SortedMap<String, String> sortedParamMap)
{
if (sortedParamMap.isEmpty()) {
return "";
}

StringBuffer buffer = new StringBuffer();
Iterator<Map.Entry<String, String>> iter =
sortedParamMap.entrySet().iterator();

while (iter.hasNext()) {
Map.Entry<String, String> kvpair = iter.next();
buffer.append(percentEncodeRfc3986(kvpair.getKey()));
buffer.append("=");
buffer.append(percentEncodeRfc3986(kvpair.getValue()));
if (iter.hasNext()) {
buffer.append("&");
}
}
String cannoical = buffer.toString();
return cannoical;
}

private String percentEncodeRfc3986(String s) {
String out;
try {
out = URLEncoder.encode(s, UTF8_CHARSET)
.replace("+", "%20")
.replace("*", "%2A")
.replace("%7E", "~");
} catch (UnsupportedEncodingException e) {
out = s;
}
return out;
}

}


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