我尝试使用SHA-512实现一个散列整数数组的程序。我找到了一些solution1 solution2来将包含十进制值的byte[]转换为十六进制。当我将字符串输出与十进制值进行比较时，我发现对于负值，存在一些差异。我不知道是什么问题。我试图将值互相转换，也看了无符号等，但我找不到有什么问题。
仅供参考，我想在xor函数中使用字节并且不需要字符串，但我担心我的代码中可能有些错误。
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;
}
}
输出结果是：
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
答案 0 :(得分：0)
保持一个字节可以具有的最大值的常量，2 ^ 7-1
这意味着每个字节的值介于-127和127之间，最高有效位用作符号标志。因此，
bytes[0] = decimal is 15 hexadecimal 0f and binary is 0000 1111
bytes[1] = decimal is -27 hexadecimal e5 and binary is 1110 0101 is 229 unsigned
bytes[2] = decimal is 36 hexadecimal 24 and binary is 0010 0100
bytes[3] = decimal is 106 hexadecimal 6a and binary is 0110 1010
bytes[4] = decimal is 42 hexadecimal 2a and binary is 0010 1010
bytes[5] = decimal is 38 hexadecimal 26 and binary is 0010 0110
bytes[6] = decimal is 8 hexadecimal 08 and binary is 0000 1000
bytes[7] = decimal is 1 hexadecimal 01 and binary is 0000 0001
然后，Java字节被签名并被解释为两个补码，这意味着所有位都被反转并加1。因此，对于e5或229或1110 0101
1110 0101 --twoCom-＆gt; 0001 1010 - （+ 1） - ＆gt; 0001 1011（27）
应用符号位---＆gt; -27