OAuthUtil.java

package appengine.util;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;

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

/**
 * utilities for oauth of google app engine.
 * @author shin1ogawa
 */
public class OAuthUtil {

	static final String ENC = "utf-8";

	static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";


	/**
	 * @param method
	 * @param requestUrlBase
	 * @param parameters
	 * @param consumerKey
	 * @param consumerSecret
	 * @param accessToken
	 * @param accessTokenSecret
	 * @return value for Authorization Header
	 * @throws UnsupportedEncodingException
	 * @throws InvalidKeyException
	 * @throws NoSuchAlgorithmException
	 * @author shin1ogawa
	 */
	public static String getAuthorizationHeaderValue(String method, String requestUrlBase,
			Map<String, String> parameters, String consumerKey, String consumerSecret,
			String accessToken, String accessTokenSecret) throws UnsupportedEncodingException,
			InvalidKeyException, NoSuchAlgorithmException {
		Map<String, String> _params = new LinkedHashMap<String, String>();
		if (parameters != null && parameters.isEmpty() == false) {
			_params.putAll(parameters);
		}
		_params.put("oauth_consumer_key", consumerKey);
		_params.put("oauth_nonce", generateNonce());
		_params.put("oauth_signature_method", "HMAC-SHA1");
		_params.put("oauth_timestamp", generateTimestamp());
		_params.put("oauth_token", accessToken);
		_params.put("oauth_version", "1.0");
		String baseString = generateSignatureBaseString(method, requestUrlBase, _params);

		String key =
				URLEncoder.encode(consumerKey, "utf-8") + "&"
						+ URLEncoder.encode(accessTokenSecret, "utf-8");
		String signature = URLEncoder.encode(generateHmacSha1Signature(key, baseString), ENC);

		StringBuilder b = new StringBuilder("OAuth ");
		if (_params.containsKey("oauth_body_hash")) {
			b.append("oauth_body_hash").append("=\"").append(_params.get("oauth_body_hash"))
				.append("\",");
		}
		b.append("oauth_consumer_key").append("=\"")
			.append(URLEncoder.encode(consumerKey, "utf-8")).append("\"");
		b.append(",oauth_token").append("=\"").append(URLEncoder.encode(accessToken, "utf-8"))
			.append("\"");
		b.append(",oauth_version").append("=\"").append("1.0").append("\"");
		b.append(",oauth_timestamp").append("=\"").append(_params.get("oauth_timestamp"))
			.append("\"");
		b.append(",oauth_nonce").append("=\"").append(_params.get("oauth_nonce")).append("\"");
		b.append(",oauth_signature_method").append("=\"").append("HMAC-SHA1").append("\"");
		b.append(",oauth_signature").append("=\"").append(signature).append("\"");
		return b.toString();
	}

	static String generateSignatureBaseString(String method, String requestUrlBase,
			Map<String, String> params) throws UnsupportedEncodingException {
		return escapeAndJoinStrings(Arrays.asList(method, requestUrlBase,
				escapeAndJoinParameters(params)));
	}

	static String escapeAndJoinParameters(Map<String, String> params)
			throws UnsupportedEncodingException {
		StringBuilder b = new StringBuilder();
		boolean first = true;
		for (String key : sortedKeyList(params)) {
			if (first == false) {
				b.append('&');
			} else {
				first = false;
			}
			b.append(key).append('=')
				.append(URLEncoder.encode(params.get(key), ENC).replace("+", "%20"));
		}
		return b.toString();
	}

	static List<String> sortedKeyList(Map<String, String> map) {
		List<String> list = new ArrayList<String>(map.keySet());
		Collections.sort(list);
		return list;
	}

	static String escapeAndJoinStrings(Iterable<String> params) throws UnsupportedEncodingException {
		StringBuilder b = new StringBuilder();
		boolean first = true;
		for (String s : params) {
			if (first == false) {
				b.append('&');
			} else {
				first = false;
			}
			b.append(URLEncoder.encode(s, ENC));
		}
		return b.toString();
	}

	static String generateHmacSha1Signature(String key, String data)
			throws NoSuchAlgorithmException, InvalidKeyException, IllegalStateException,
			UnsupportedEncodingException {
		SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(ENC), HMAC_SHA1_ALGORITHM);
		Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
		mac.init(signingKey);
		return byteArrayToBase64String(mac.doFinal(data.getBytes(ENC)));
	}

	static String generateTimestamp() {
		return Long.toString(System.currentTimeMillis() / 1000L);
	}

	static String generateNonce() {
		return Long.toString(new Random().nextLong());
	}

	static String byteArrayToBase64String(byte[] bytes) {
		int bytesLength = bytes.length;
		int fullGroups = bytesLength / 3;
		int partialGroup = bytesLength - 3 * fullGroups;
		int resultLength = 4 * ((bytesLength + 2) / 3);
		StringBuilder b = new StringBuilder(resultLength);
		int cursor = 0;
		for (int i = 0; i < fullGroups; i++) {
			int byte0 = bytes[cursor++] & 0xff;
			int byte1 = bytes[cursor++] & 0xff;
			int byte2 = bytes[cursor++] & 0xff;
			b.append(intToBase64[byte0 >> 2]);
			b.append(intToBase64[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
			b.append(intToBase64[(byte1 << 2) & 0x3f | (byte2 >> 6)]);
			b.append(intToBase64[byte2 & 0x3f]);
		}

		if (partialGroup != 0) {
			int byte0 = bytes[cursor++] & 0xff;
			b.append(intToBase64[byte0 >> 2]);
			if (partialGroup == 1) {
				b.append(intToBase64[(byte0 << 4) & 0x3f]);
				b.append("==");
			} else {
				int byte1 = bytes[cursor++] & 0xff;
				b.append(intToBase64[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
				b.append(intToBase64[(byte1 << 2) & 0x3f]);
				b.append('=');
			}
		}
		return b.toString();
	}


	static final char intToBase64[] = {
		'A',
		'B',
		'C',
		'D',
		'E',
		'F',
		'G',
		'H',
		'I',
		'J',
		'K',
		'L',
		'M',
		'N',
		'O',
		'P',
		'Q',
		'R',
		'S',
		'T',
		'U',
		'V',
		'W',
		'X',
		'Y',
		'Z',
		'a',
		'b',
		'c',
		'd',
		'e',
		'f',
		'g',
		'h',
		'i',
		'j',
		'k',
		'l',
		'm',
		'n',
		'o',
		'p',
		'q',
		'r',
		's',
		't',
		'u',
		'v',
		'w',
		'x',
		'y',
		'z',
		'0',
		'1',
		'2',
		'3',
		'4',
		'5',
		'6',
		'7',
		'8',
		'9',
		'+',
		'/'
	};
}