sha256哈希值java_Java 使用MD5､SHA1､SHA-256和SHA-512计算文件和字符串哈希值(hash checksum)...

1､计算文件哈希值(hash) Hashpackage com.memorynotfound.file;

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

import java.security.MessageDigest;

public enum Hash {

MD5("MD5"),

SHA1("SHA1"),

SHA256("SHA-256"),

SHA512("SHA-512");

private String name;

Hash(String name) {

this.name = name;

}

public String getName() {

return name;

}

public byte[] checksum(File input) {

try (InputStream in = new FileInputStream(input)) {

MessageDigest digest = MessageDigest.getInstance(getName());

byte[] block = new byte[4096];

int length;

while ((length = in.read(block)) > 0) {

digest.update(block, 0, length);

}

return digest.digest();

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

}

使用示例代码：package com.memorynotfound.file;

import javax.xml.bind.DatatypeConverter;

import java.io.File;

public class FileChecksumExample {

public static void main(String[] args) throws Exception {

File file = new File("/tmp/cjavapy.pdf");

System.out.println("MD5 : " + toHex(Hash.MD5.checksum(file)));

System.out.println("SHA1 : " + toHex(Hash.SHA1.checksum(file)));

System.out.println("SHA256 : " + toHex(Hash.SHA256.checksum(file)));

System.out.println("SHA512 : " + toHex(Hash.SHA512.checksum(file)));

}

private static String toHex(byte[] bytes) {

return DatatypeConverter.printHexBinary(bytes);

}

}

2､计算字符串哈希值(hash) Hash

盐(Salt): 在密码学中，是指通过在密码任意固定位置插入特定的字符串，让散列后的结果和使用原始密码的散列结果不相符，这种过程称之为“加盐”。

1) 使用MD5计算public class SimpleMD5Example

{

public static void main(String[] args)

{

String passwordToHash = "password";

String generatedPassword = null;

try {

// 为MD5创建MessageDigest实例

MessageDigest md = MessageDigest.getInstance("MD5");

//添加密码字节以进行

md.update(passwordToHash.getBytes());

//Get the hash's bytes

byte[] bytes = md.digest();

//This bytes[] has bytes in decimal format;

//将其转换为十六进制格式

StringBuilder sb = new StringBuilder();

for(int i=0; i< bytes.length ;i++)

{

sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));

}

//得到完整的哈希密码在十六进制格式

generatedPassword = sb.toString();

}

catch (NoSuchAlgorithmException e)

{

e.printStackTrace();

}

System.out.println(generatedPassword);

}

}

输出:5f4dcc3b5aa765d61d8327deb882cf99

2) 使用SHA1计算package com.cjavapy.hashing.password.demo.sha;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

public class SHAExample {

public static void main(String[] args) throws NoSuchAlgorithmException

{

String passwordToHash = "password";

byte[] salt = getSalt();

String securePassword = get_SHA_SecurePassword(passwordToHash, salt);

System.out.println(securePassword);

}

private static String get_SHA_SecurePassword(String passwordToHash, byte[] salt)

{

String generatedPassword = null;

try {

MessageDigest md = MessageDigest.getInstance("SHA-1");

//MessageDigest md = MessageDigest.getInstance("SHA-256");

//MessageDigest md = MessageDigest.getInstance("SHA-512");

md.update(salt);

byte[] bytes = md.digest(passwordToHash.getBytes());

StringBuilder sb = new StringBuilder();

for(int i=0; i< bytes.length ;i++)

{

sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));

}

generatedPassword = sb.toString();

}

catch (NoSuchAlgorithmException e)

{

e.printStackTrace();

}

return generatedPassword;

}

//Add salt

private static byte[] getSalt() throws NoSuchAlgorithmException

{

SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");

byte[] salt = new byte[16];

sr.nextBytes(salt);

return salt;

}

}

输出:

1)SHA1:

e4c53afeaa7a08b1f27022abd443688c37981bc4

2)SHA256:

87adfd14a7a89b201bf6d99105b417287db6581d8aee989076bb7f86154e8f32

3)SHA512:

529211542985b8f7af61994670d03d25d55cc9cd1cff8d57bb799c4b586891e112b197530c76744bcd7ef135b58d47d65a0bec221eb5d77793956cf2709dd012

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