JAVA中常用的加密算法总结

时间：2021-11-18 19:11:29

项目中第一次深入地了解到加密算法的使用，现第一阶段结束，将使用到的加密算法和大家分享一下：

首先还是先给大家普及一下常用加密算法的基础知识

基本的单向加密算法

  • BASE64 严格地说，属于编码格式，而非加密算法
  • MD5(Message Digest algorithm 5，信息摘要算法)
  • SHA(Secure Hash Algorithm，安全散列算法)

复杂的加密算法

  • RSA(算法的名字以发明者的名字命名：Ron Rivest, AdiShamir 和Leonard Adleman)
  • DES/3DES(Digital Signature Algorithm，数字签名)

国密算法

  • SM2/SM4(是由国家密码管理局编制的一种商用密码分组标准对称算法)

使用方法：

base64

public static byte[] encode2Base64(byte[] bytes) {
byte[] bts = Base64.encodeBase64(bytes);
return bts;
    }

public static byte[] decode2Base64(String str) {
byte[] bts = Base64.decodeBase64(str);
return bts;
    }

MD5

public static String md5(String str) {
try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
return new String(digest.digest(str.getBytes()));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
return "";
    }

SHA-1

public static byte[] sha1ToBytes(String str) {
try {
            MessageDigest digest = MessageDigest.getInstance("SHA-1");
byte[] bts = digest.digest(str.getBytes());
return bts;
        } catch (Exception e) {
            e.printStackTrace();
        }
return null;
    }

DES/3DES

public static byte[] encryptMode(String keyStr, byte[] src) {

try {
// 生成密钥
            SecretKey deskey = new SecretKeySpec(keyStr.getBytes(), "DESede");
// 加密
            Cipher c1 = Cipher.getInstance("DESede");
            c1.init(Cipher.ENCRYPT_MODE, deskey);
return c1.doFinal(src);
        } catch (java.security.NoSuchAlgorithmException e1) {
            e1.printStackTrace();
        } catch (javax.crypto.NoSuchPaddingException e2) {
            e2.printStackTrace();
        } catch (java.lang.Exception e3) {
            e3.printStackTrace();
        }
return null;
    }


public static byte[] decryptMode(String keyStr, byte[] src) {
try {
            SecretKey deskey = new SecretKeySpec(keyStr.getBytes(), "DESede");
// 解密
            Cipher c1 = Cipher.getInstance("DESede");
            c1.init(Cipher.DECRYPT_MODE, deskey);
return c1.doFinal(src);
        } catch (java.security.NoSuchAlgorithmException e1) {
            e1.printStackTrace();
        } catch (javax.crypto.NoSuchPaddingException e2) {
            e2.printStackTrace();
        } catch (java.lang.Exception e3) {
            e3.printStackTrace();
        }
return null;
    }

RSA

/**
 * 初始化公密钥
 * 
 * @return
 * @throws Exception
 */
public static Map<String, Object> initKey() throws Exception {
        KeyPairGenerator kpGenerator = KeyPairGenerator.getInstance("RSA");
        kpGenerator.initialize(2048);
        KeyPair keyPair = kpGenerator.generateKeyPair();
// 存储公钥
        PublicKey publicKey = keyPair.getPublic();
// 存储密钥
        PrivateKey privateKey = keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>();
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);

return keyMap;
    }

/**
 * 取出公钥
 * 
 * @param keyMap
 * @return
 */
public static String getPublicKey(Map<String, Object> keyMap) {
        Key key = (Key) keyMap.get("RSAPublicKey");
return encode2Base64(new String(key.getEncoded()));
    }

/**
 * 取出密钥
 * 
 * @param keyMap
 * @return
 */
public static String getPrivateKey(Map<String, Object> keyMap) {
        Key key = (Key) keyMap.get("RSAPrivateKey");
return encode2Base64(new String(key.getEncoded()));
    }

/**
 * 公钥加密
 * 
 * @param data
 * @param publicKey
 * @return
 * @throws Exception
 */
public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
// 模长
int key_len = publicKey.getModulus().bitLength() / 8;
// 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
// 如果明文长度大于模长-11则要分组加密
for (String s : datas) {
            mi += bcd2Str(cipher.doFinal(s.getBytes()));
        }
return mi;
    }

/**
 * 私钥加密
 * 
 * @param data
 * @param privateKey
 * @return
 * @throws Exception
 */
public static String encryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
// 模长
int key_len = privateKey.getModulus().bitLength() / 8;
// 加密数据长度 <= 模长-11
        String[] datas = splitString(data, key_len - 11);
        String mi = "";
// 如果明文长度大于模长-11则要分组加密
for (String s : datas) {
            mi += bcd2Str(cipher.doFinal(s.getBytes()));
        }

return mi;
    }

/**
 * 私钥解密
 * 
 * @param data
 * @param privateKey
 * @return
 * @throws Exception
 */
public static String decryptByPrivateKey(String data,
            RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
// 模长
int key_len = privateKey.getModulus().bitLength() / 8;
byte[] bytes = data.getBytes();
byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
        System.err.println(bcd.length);
// 如果密文长度大于模长则要分组解密
        String ming = "";
byte[][] arrays = splitArray(bcd, key_len);
for (byte[] arr : arrays) {
            ming += new String(cipher.doFinal(arr));
        }
return ming;
    }

/**
 * ASCII码转BCD码
 * 
 */
public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
byte[] bcd = new byte[asc_len / 2];
int j = 0;
for (int i = 0; i < (asc_len + 1) / 2; i++) {
            bcd[i] = asc_to_bcd(ascii[j++]);
            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
        }
return bcd;
    }

public static byte asc_to_bcd(byte asc) {
byte bcd;

if ((asc >= '0') && (asc <= '9'))
            bcd = (byte) (asc - '0');
else if ((asc >= 'A') && (asc <= 'F'))
            bcd = (byte) (asc - 'A' + 10);
else if ((asc >= 'a') && (asc <= 'f'))
            bcd = (byte) (asc - 'a' + 10);
else
            bcd = (byte) (asc - 48);
return bcd;
    }

/**
 * BCD转字符串
 */
public static String bcd2Str(byte[] bytes) {
char temp[] = new char[bytes.length * 2], val;

for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
return new String(temp);
    }

/**
 * 拆分字符串
 */
public static String[] splitString(String string, int len) {
int x = string.length() / len;
int y = string.length() % len;
int z = 0;
if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
for (int i = 0; i < x + z; i++) {
if (i == x + z - 1 && y != 0) {
                str = string.substring(i * len, i * len + y);
            } else {
                str = string.substring(i * len, i * len + len);
            }
            strings[i] = str;
        }
return strings;
    }

/**
 * 拆分数组
 */
public static byte[][] splitArray(byte[] data, int len) {
int x = data.length / len;
int y = data.length % len;
int z = 0;
if (y != 0) {
            z = 1;
        }
byte[][] arrays = new byte[x + z][];
byte[] arr;
for (int i = 0; i < x + z; i++) {
            arr = new byte[len];
if (i == x + z - 1 && y != 0) {
                System.arraycopy(data, i * len, arr, 0, y);
            } else {
                System.arraycopy(data, i * len, arr, 0, len);
            }
            arrays[i] = arr;
        }
return arrays;
    }

以上就是本次项目中用到的加密算法，需要注意的是编码格式一定要双方统一 ，如果不一致则加解密不成功。
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