com.realexpayments.remote.sdk.utils.GenerationUtils Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of rxp-remote-java Show documentation
The official Realex Payments Remote Java SDK
The newest version!
package com.realexpayments.remote.sdk.utils;

import java.nio.ByteBuffer;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

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

/**
 * Utils for the auto-generation of fields, for example the SHA1 hash.
 *
 * @author thomasduffy
 */
public class GenerationUtils {

	/**
	 * Each message sent to Realex should have a hash, attached. For a message using the remote 
	 * interface this is generated using the This is generated from the TIMESTAMP, MERCHANT_ID, 
	 * ORDER_ID, AMOUNT, and CURRENCY fields concatenated together with "." in between each field.  
	 * This confirms the message comes 
	 * from the client and 
	 * Generate a hash, required for all messages sent to IPS to prove it was not tampered with. 
	 * 
	 * Hashing takes a string as input, and produce a fixed size number (160 bits for SHA-1 which 
	 * this implementation uses). This number is a hash of the input, and a small change in the 
	 * input results in a substantial change in the output. The functions are thought to be secure 
	 * in the sense that it requires an enormous amount of computing power and time to find a string 
	 * that hashes to the same value. In others words, there's no way to decrypt a secure hash. 
	 * Given the larger key size, this implementation uses SHA-1 which we prefer that you, but Realex 
	 * has retained compatibilty with MD5 hashing for compatibility with older systems.
	 * 

	 * 

	 * To construct the hash for the remote interface follow this procedure: 
	 * 
	 * To construct the hash for the remote interface follow this procedure: 
	 * Form a string by concatenating the above fields with a period ('.') in the following order
	 * 

	 * (TIMESTAMP.MERCHANT_ID.ORDER_ID.AMOUNT.CURRENCY)
	 * 

	 * Like so (where a field is empty an empty string "" is used):
	 * 

	 * (20120926112654.thestore.ORD453-11.29900.EUR)
	 * 

	 * Get the hash of this string (SHA-1 shown below).
	 * 

	 * (b3d51ca21db725f9c7f13f8aca9e0e2ec2f32502)
	 * 

	 * Create a new string by concatenating this string and your shared secret using a period.
	 * 

	 * (b3d51ca21db725f9c7f13f8aca9e0e2ec2f32502.mysecret )
	 * 

	 * Get the hash of this value. This is the value that you send to Realex Payments.
	 * 
	 * (3c3cac74f2b783598b99af6e43246529346d95d1)
	 *
	 * This method takes the pre-built string of concatenated fields and the secret and returns the 
	 * SHA-1 hash to be placed in the request sent to Realex.
	 * 
	 * @param toHash
	 * @param secret
	 * @return the hash as a hex string
	 */
	static public String generateHash(String toHash, String secret) {
		//first pass hashes the String of required fields
		String toHashFirstPass = DigestUtils.sha1Hex(toHash);

		//second pass takes the first hash, adds the secret and hashes again
		String toHashSecondPass = new StringBuilder().append(toHashFirstPass).append(".").append(secret).toString();
		return DigestUtils.sha1Hex(toHashSecondPass);
	}

	/**
	 * Generate the current datetimestamp in the string formaat (YYYYMMDDHHSS) required in a  
	 * request to Realex.
	 * 
	 * @return current timestamp in YYYYMMDDHHSS format
	 */
	static public String generateTimestamp() {
		return new SimpleDateFormat("yyyyMMddHHmmss").format(new Date());
	}

	/**
	 * Order Id for a initial request should be unique per client ID. This method generates a unique 
	 * order Id using the Java UUID class and then convert it to base64 to shorten the length to 22 
	 * characters. Order Id for a subsequent request (void, rebate, settle ect.) should use the 
	 * order Id of the initial request.
	 * 
	 * * the order ID uses the Java UUID (universally unique identifier) so in theory it may not 
	 * be unique but the odds of this are extremely remote (see 
	 * http://en.wikipedia.org/wiki/Universally_unique_identifier#Random_UUID_probability_of_duplicates)
	 * 
	 * @return orderId as a String 
	 */
	static public String generateOrderId() {
		UUID uuid = UUID.randomUUID();
		ByteBuffer bb = ByteBuffer.wrap(new byte[16]);

		bb.putLong(uuid.getMostSignificantBits());
		bb.putLong(uuid.getLeastSignificantBits());
		return Base64.encodeBase64URLSafeString(bb.array());
	}

}