I have tried to implement a program to hash an integer array using SHA-512. I found some solution1 solution2 to convert the byte[] which contains decimal values to hexadecimals. When I compared the string output to decimal values I found out that for negative values there are some differences. I don't know what is the problem. I tried to convert values to each other and also looked at unsigned, etc but I can not found out what is wrong.
FYI, I want to use bytes in an xor function and don't need strings but I'm scared that some thing might be wrong in my code.
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Formatter;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author martin
*/
public class NewMain {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
Integer[][] integerBlock = new Integer[5][5];
//put some values in the matrix integerBlock
int i,j;
for(i=0; i<integerBlock.length; i++){
for(j=0; j<integerBlock.length; j++){
integerBlock[i][j] = i+j;
}
}
//convert integerBlock to a string
String str = IntToStr(integerBlock);
System.out.println("original string is : " + str);
//hash the string using SHA512
byte[] shaByteResult = SHA512(str);
//print the generated key in hex
System.out.println("byteArray2Hex method: " + byteArray2Hex(shaByteResult));
System.out.println("byteArray2Hex2 method: " + byteArray2Hex2(shaByteResult));
//print the generated key in decimal
System.out.print("Decimal values in bytes[]:");
for(i=0; i< shaByteResult.length ;i++)
System.out.print(shaByteResult[i]);
System.out.println("Compare decimal and correspondig hex");
for(i=0; i< shaByteResult.length ;i++)
System.out.println("bytes[" +i +"] = " + " decimal is " + shaByteResult[i] + " hexadecimal " + Integer.toString((shaByteResult[i] & 0xff) + 0x100, 16).substring(1));
}
public static String IntToStr(Integer[][] integerBlock){
StringBuilder SB = new StringBuilder();
int i,j;
for(i=0; i<integerBlock.length; i++){
for(j=0; j<integerBlock.length; j++){
SB.append(integerBlock[i][j].toString());
//stringBlock = stringBlock.concat(integerBlock[i][j].toString());
}
}
return SB.toString();
}
private static String byteArray2Hex(final byte[] bytes) {
Formatter formatter = new Formatter();
for (byte b : bytes) {
formatter.format("%02x", b);
}
return formatter.toString();
}
//another solution
private static String byteArray2Hex2(final byte[] bytes) {
StringBuilder sb = new StringBuilder();
int i;
for(i=0; i< bytes.length ;i++)
sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));
return sb.toString();
}
public static byte[] SHA512(String str){
byte[] bytes = null;
try {
MessageDigest md = MessageDigest.getInstance("SHA-512");
md.update(str.getBytes());
bytes = md.digest();
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(NewMain.class.getName()).log(Level.SEVERE, null, ex);
}
return bytes;
}
}
The out put is:
original string is : 0123412345234563456745678
byteArray2Hex method: 0fe5246a2a26080194c19e86ee1e6a40ceb298194190eacace0d3b1499186220b5cd92a1bdd25f8b4023566c211cc462974c3884a128336b76a1e990fe6f3c54
byteArray2Hex2 method: 0fe5246a2a26080194c19e86ee1e6a40ceb298194190eacace0d3b1499186220b5cd92a1bdd25f8b4023566c211cc462974c3884a128336b76a1e990fe6f3c54
Decimal values in bytes[]:15-2736106423881-108-63-98-122-183010664-50-78-1042565-112-22-54-50135920-103249832-75-51-110-95-67-4695-1176435861083328-6098-1057656-124-954051107118-95-23-112-21116084Compare decimal and correspondig hex
bytes[0] = decimal is 15 hexadecimal 0f
bytes[1] = decimal is -27 hexadecimal e5
bytes[2] = decimal is 36 hexadecimal 24
bytes[3] = decimal is 106 hexadecimal 6a
bytes[4] = decimal is 42 hexadecimal 2a
bytes[5] = decimal is 38 hexadecimal 26
bytes[6] = decimal is 8 hexadecimal 08
bytes[7] = decimal is 1 hexadecimal 01
bytes[8] = decimal is -108 hexadecimal 94
bytes[9] = decimal is -63 hexadecimal c1
bytes[10] = decimal is -98 hexadecimal 9e
bytes[11] = decimal is -122 hexadecimal 86
bytes[12] = decimal is -18 hexadecimal ee
bytes[13] = decimal is 30 hexadecimal 1e
bytes[14] = decimal is 106 hexadecimal 6a
bytes[15] = decimal is 64 hexadecimal 40
bytes[16] = decimal is -50 hexadecimal ce
bytes[17] = decimal is -78 hexadecimal b2
bytes[18] = decimal is -104 hexadecimal 98
bytes[19] = decimal is 25 hexadecimal 19
bytes[20] = decimal is 65 hexadecimal 41
bytes[21] = decimal is -112 hexadecimal 90
bytes[22] = decimal is -22 hexadecimal ea
bytes[23] = decimal is -54 hexadecimal ca
bytes[24] = decimal is -50 hexadecimal ce
bytes[25] = decimal is 13 hexadecimal 0d
bytes[26] = decimal is 59 hexadecimal 3b
bytes[27] = decimal is 20 hexadecimal 14
bytes[28] = decimal is -103 hexadecimal 99
bytes[29] = decimal is 24 hexadecimal 18
bytes[30] = decimal is 98 hexadecimal 62
bytes[31] = decimal is 32 hexadecimal 20
bytes[32] = decimal is -75 hexadecimal b5
bytes[33] = decimal is -51 hexadecimal cd
bytes[34] = decimal is -110 hexadecimal 92
bytes[35] = decimal is -95 hexadecimal a1
bytes[36] = decimal is -67 hexadecimal bd
bytes[37] = decimal is -46 hexadecimal d2
bytes[38] = decimal is 95 hexadecimal 5f
bytes[39] = decimal is -117 hexadecimal 8b
bytes[40] = decimal is 64 hexadecimal 40
bytes[41] = decimal is 35 hexadecimal 23
bytes[42] = decimal is 86 hexadecimal 56
bytes[43] = decimal is 108 hexadecimal 6c
bytes[44] = decimal is 33 hexadecimal 21
bytes[45] = decimal is 28 hexadecimal 1c
bytes[46] = decimal is -60 hexadecimal c4
bytes[47] = decimal is 98 hexadecimal 62
bytes[48] = decimal is -105 hexadecimal 97
bytes[49] = decimal is 76 hexadecimal 4c
bytes[50] = decimal is 56 hexadecimal 38
bytes[51] = decimal is -124 hexadecimal 84
bytes[52] = decimal is -95 hexadecimal a1
bytes[53] = decimal is 40 hexadecimal 28
bytes[54] = decimal is 51 hexadecimal 33
bytes[55] = decimal is 107 hexadecimal 6b
bytes[56] = decimal is 118 hexadecimal 76
bytes[57] = decimal is -95 hexadecimal a1
bytes[58] = decimal is -23 hexadecimal e9
bytes[59] = decimal is -112 hexadecimal 90
bytes[60] = decimal is -2 hexadecimal fe
bytes[61] = decimal is 111 hexadecimal 6f
bytes[62] = decimal is 60 hexadecimal 3c
bytes[63] = decimal is 84 hexadecimal 54
