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Thread: hmac sha256

  1. #1
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    Default hmac sha256

    Hi, I have to derive the signing key (encyption mode hmac sha256) for an aws project. This is my problem, but something is going wrong I think because I'm not able to call the two methods at the end of the program in the right way. And also I'm not able to print the final value of ksigning. Can you help me?
    I report my code. Thank you very much.



    package signature;
     
    import org.apache.commons.codec.binary.Hex;
    //import java.io.UnsupportedEncodingException;
    //import java.security.InvalidKeyException;
    //import java.security.NoSuchAlgorithmException;
     
    import java.io.UnsupportedEncodingException;
    import java.security.InvalidKeyException;
     
    import javax.crypto.Mac;
    import javax.crypto.spec.SecretKeySpec;
     
     
    public class signing_key3 {
    	public static void main(String[] args)  
    	{
    		String key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		String dateStamp="20180713T111300Z";
    		String regionName="eu-west-1";
    		String serviceName="iotdata";
    		String data="20180713";
    		String algorithm="HmacSHA256";
    		//byte[] key1=key.getBytes();
    		//byte[] data1=data.getBytes();
    		try
    		{
    		Mac HmacSHA256 =Mac.getInstance(algorithm);
    		 SecretKeySpec kSecret = new SecretKeySpec(key.getBytes("UTF-8"), algorithm); 
    		// HmacSHA256.init(kSecret);
    		 //String foo = "I am a string";
             //byte[] kSecret1=kSecret.getBytes();
             //System.out.println( Hex.encodeHexString( kSecret1));
    		 /* byte[] key1=key.getBytes();*/
    			/*HmacSHA256.HmacSHA256(/*String data, String key);*/
    			/*HmacSHA256.getSignatureKey(/*String key, String dateStamp, String regionName, String serviceName);*/
     
    		//byte[] s = HmacSHA256( data,  key);
    		//HmacSHA256( data,  key);
     
    		}
    		catch(Exception e)
    		{
    			e.printStackTrace();
    		}
    		//System.out.println(kSigning);
    	}
     
    	//class HmacSHA256{
    		static byte[] HmacSHA256( String data, String key) throws Exception 
     
    	{
    		key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		data="20180713";
    		String algorithm="HmacSHA256";
     
    		byte[] key1=key.getBytes();
    	   // byte[] data1=data.getBytes();
    		Mac mac = Mac.getInstance(algorithm);
    	    mac.init(new SecretKeySpec(key1, algorithm));
    	    return mac.doFinal(data.getBytes("UTF8"));
    	}
     
    	//class getSignatureKey{
    	static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName) throws Exception 
    	{
    		   key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		   dateStamp="20180713T111300Z";
    		   regionName="eu-west-1";
    		   serviceName="iotdata";
    		String algorithm="HmacSHA256";
    		byte[] kSecret = ("AWS4" + key).getBytes("UTF8");
    		String kSecret1=kSecret.toString();
    		byte[] kDate =HmacSHA256(dateStamp, kSecret1);
    		String kDate1=kDate.toString();
    		byte[] kRegion = HmacSHA256(regionName, kDate1);
    		String kRegion1=kRegion.toString();
    		byte[] kService = HmacSHA256(serviceName, kRegion1);
    		String kService1=kService.toString();
    		byte[] kSigning = HmacSHA256("aws4_request", kService1);
    		//String kSigning1=kSigning.toString();
    		System.out.println( Hex.encodeHexString( kSigning));
    		return kSigning;
    	}
    }
    Last edited by Norm; July 16th, 2018 at 05:43 AM. Reason: Added code tags

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: hmac sha256

    I'm not able to call the two methods at the end of the program in the right way. And also I'm not able to print the final value of ksigning
    Please show what happens when you compile and execute the code.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: hmac sha256

    I'm using eclipse: there is no error but nothing shown on console.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: hmac sha256

    Does the code call any methods to execute a print statement that will show on the console?

    The code that could call a method is commented out. Remove the //s and the /* */s so that the code will compile and execute.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: hmac sha256

    I did some little changes and removed comments and tryed to print kSigning. Follows the code and error message. It seems that I'm not able to call the two methods inside the main.

    Java code

    package signature;

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


    import java.io.UnsupportedEncodingException;
    import java.security.InvalidKeyException;

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


    public class signing_key3a {
    public static void main(String[] args)
    {
    String key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    String dateStamp="20180713T111300Z";
    String regionName="eu-west-1";
    String serviceName="iotdata";
    String data="20180713";
    String algorithm="HmacSHA256";

    try
    {
    Mac HmacSHA256 =Mac.getInstance(algorithm);
    SecretKeySpec kSecret = new SecretKeySpec(key.getBytes("UTF-8"), algorithm);
    System.out.println(kSigning);

    }
    catch(Exception e)
    {
    e.printStackTrace();
    }

    }




    static byte[] HmacSHA256( String data, String key) throws Exception

    {
    key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    data="20180713";
    String algorithm="HmacSHA256";

    byte[] key1=key.getBytes();

    Mac mac = Mac.getInstance(algorithm);
    mac.init(new SecretKeySpec(key1, algorithm));
    return mac.doFinal(data.getBytes("UTF8"));
    }


    static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName) throws Exception
    {
    key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    dateStamp="20180713T111300Z";
    regionName="eu-west-1";
    serviceName="iotdata";
    String algorithm="HmacSHA256";
    byte[] kSecret = ("AWS4" + key).getBytes("UTF8");
    String kSecret1=kSecret.toString();
    byte[] kDate =HmacSHA256(dateStamp, kSecret1);
    String kDate1=kDate.toString();
    byte[] kRegion = HmacSHA256(regionName, kDate1);
    String kRegion1=kRegion.toString();
    byte[] kService = HmacSHA256(serviceName, kRegion1);
    String kService1=kService.toString();
    byte[] kSigning = HmacSHA256("aws4_request", kService1);

    System.out.println( Hex.encodeHexString( kSigning));
    return kSigning;
    }

    }

    /code


    MESSAGE

    kSigning cannot be resolved to a variable

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: hmac sha256

    Please edit your post and wrap your code with code tags:

    [code]
    **YOUR CODE GOES HERE**
    [/code]

    to get highlighting and preserve formatting.

    kSigning cannot be resolved to a variable
    Where does that error happen?
    The compiler can not find a definition for kSigning that is in scope for where it is used.
    If you don't understand my answer, don't ignore it, ask a question.

  7. #7
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    Default Re: hmac sha256

    Finally I solved! Ipost the orrect code, perhaps it can help someone. There were two problems: the first was that I was not calling the methods inside the main, the second was that I should rename the variable kSigning inside the main to print it bacause the method rename just the value, not the variable. Thank you very much for your help!


     
    package signature;
     
    import org.apache.commons.codec.binary.Hex;
     
     
    import java.io.UnsupportedEncodingException;
    import java.security.InvalidKeyException;
     
    import javax.crypto.Mac;
    import javax.crypto.spec.SecretKeySpec;
     
     
    public class signing_key3a {
    	public static void main(String[] args)  throws Exception
    	{
    		String key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		String dateStamp="20180713T111300Z";
    		String regionName="eu-west-1";
    		String serviceName="iotdata";
    		String data="20180713";
    		String algorithm="HmacSHA256";
    		//byte[] kSigning2 = getSignatureKey( key, dateStamp, regionName,  serviceName);
    		HmacSHA256( data, key);
    		try
    		{
    			//getSignatureKey( key, dateStamp, regionName,  serviceName);	
    		Mac HmacSHA256 =Mac.getInstance(algorithm);
    		SecretKeySpec kSecret = new SecretKeySpec(key.getBytes("UTF-8"), algorithm); 
    		 //System.out.println(kSigning2);
    			byte[] kSigning2 = getSignatureKey( key, dateStamp, regionName,  serviceName);
    		}
    		catch(Exception e)
    		{
    			e.printStackTrace();
    		}
     
    	}
     
     
     
     
    		static byte[] HmacSHA256( String data, String key) throws Exception 
     
    	{
    		key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		data="20180713";
    		String algorithm="HmacSHA256";
     
    		byte[] key1=key.getBytes();
     
    		Mac mac = Mac.getInstance(algorithm);
    	    mac.init(new SecretKeySpec(key1, algorithm));
    	    return mac.doFinal(data.getBytes("UTF8"));
    	}
     
     
    	static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName) throws Exception 
    	{
    		   key="8cTZJ5chnb7YcUszssveBXZDTvvhhUFQd3YACxFp";
    		   dateStamp="20180713T111300Z";
    		   regionName="eu-west-1";
    		   serviceName="iotdata";
    		String algorithm="HmacSHA256";
    		byte[] kSecret = ("AWS4" + key).getBytes("UTF8");
    		String kSecret1=kSecret.toString();
    		byte[] kDate =HmacSHA256(dateStamp, kSecret1);
    		String kDate1=kDate.toString();
    		byte[] kRegion = HmacSHA256(regionName, kDate1);
    		String kRegion1=kRegion.toString();
    		byte[] kService = HmacSHA256(serviceName, kRegion1);
    		String kService1=kService.toString();
    		byte[] kSigning = HmacSHA256("aws4_request", kService1);
     
    		System.out.println( Hex.encodeHexString( kSigning));
    		return kSigning;
    	}
     
    	}

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