# 消息摘要算法
MD(Message Digest)
SHA(Secure Hash Algorithm)
MAC(Message Authentication Code)
其他如：RipeMD, Tiger, Whirlpool, GOST3411等，均由Bouncy Castle实现。
# 消息摘要算法--MD(Message Digest)
作用：验证数据的完整性
是数字签名核心算法
MD5
MD家族（128位摘要信息）-MD2，MD4
| 算法 | 摘要长度 | 实现方法 |
|---|---|---|
| MD2 | 128 | JDK |
| MD4 | 128 | Bouncy Castle |
| MD5 | 128 | JDK |
# 代码实现
package md.test;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
import org.apache.commons.codec.binary.Hex;
import org.apache.commons.codec.digest.DigestUtils;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.digests.MD2Digest;
import org.bouncycastle.crypto.digests.MD4Digest;
import org.bouncycastle.crypto.digests.MD5Digest;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
/**
* Message Digest
* @author Capricorncd
* https://github.com/capricorncd
*
*/
public class TestMessageDigest {
private static final String MD2 = "MD2";
private static final String MD4 = "MD4";
private static final String MD5 = "MD5";
public static void main(String[] args) {
String src = "I love the world.";
jdkMD(src, MD2);
jdkMD(src, MD4);
jdkMD(src, MD5);
bcMD(src, MD2, new MD2Digest());
bcMD(src, MD4, new MD4Digest());
bcMD(src, MD5, new MD5Digest());
bouncyCastleMD(src, MD2);
bouncyCastleMD(src, MD4);
bouncyCastleMD(src, MD5);
ccMD(src, MD2);
ccMD(src, MD4);
ccMD(src, MD5);
}
/**
* JDK MD
* @param src source
* @param mdType MD2,MD5
* @return String result
*/
public static String jdkMD(String src, String mdType) {
String result = null;
try {
MessageDigest md = MessageDigest.getInstance(mdType);
byte[] mdBytes = md.digest(src.getBytes());
// toHex
result = Hex.encodeHexString(mdBytes);
} catch (NoSuchAlgorithmException e) {
// e.printStackTrace();
result = e.getMessage();
}
println(mdType + ":", result, "by JDK");
return result;
}
/**
* bouncy castle MD
* @param src source
* @param mdType message digest type
* @param digest org.bouncycastle.crypto.Digest
* @return String result
*/
public static<T extends Digest> String bcMD(String src, String mdType, T digest) {
byte[] srcBytes = src.getBytes();
digest.update(srcBytes, 0, srcBytes.length);
byte[] resBytes = new byte[digest.getDigestSize()];
digest.doFinal(resBytes, 0);
String result = org.bouncycastle.util.encoders.Hex.toHexString(resBytes);
println(mdType + ":", result, "by Bouncycastle");
return result;
}
/**
* bouncy castle provider MD
* @param src source
* @param mdType message digest type
* @return String result
*/
public static String bouncyCastleMD(String src, String mdType) {
String result = null;
Security.addProvider(new BouncyCastleProvider());
try {
MessageDigest md = MessageDigest.getInstance(mdType);
byte[] mdBytes = md.digest(src.getBytes());
result = Hex.encodeHexString(mdBytes);
} catch (NoSuchAlgorithmException e) {
// e.printStackTrace();
result = e.getMessage();
}
println(mdType + ":", result, "by BouncyCastleProvider");
return result;
}
/**
* org.apache.commons.codec.digest.DigestUtils
* @param src source
* @param mdType message digest type
* @return String result
*/
public static String ccMD(String src, String mdType) {
String result = null;
switch(mdType) {
case MD2:
result = DigestUtils.md2Hex(src.getBytes());
break;
case MD4:
result = "The MD4 method is not implemented.";
break;
case MD5:
result = DigestUtils.md5Hex(src.getBytes());
break;
}
println(mdType + ":", result, "by org.apache.commons.codec.digest.DigestUtils");
return result;
}
/**
* System.out.println
* @param args
*/
public static void println(Object ...args) {
for (Object o : args) {
System.out.print(o + " ");
}
System.out.print("\n");
}
}
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运行结果：
MD2: b749ef6943db8fa96fa688a1077224a3 by JDK
MD4: MD4 MessageDigest not available by JDK
MD5: 2947f614c460347649185e62ee914eac by JDK
MD2: b749ef6943db8fa96fa688a1077224a3 by Bouncycastle
MD4: 9df4c1b595403939d490ad7c66cf7710 by Bouncycastle
MD5: 2947f614c460347649185e62ee914eac by Bouncycastle
MD2: b749ef6943db8fa96fa688a1077224a3 by BouncyCastleProvider
MD4: 9df4c1b595403939d490ad7c66cf7710 by BouncyCastleProvider
MD5: 2947f614c460347649185e62ee914eac by BouncyCastleProvider
MD2: b749ef6943db8fa96fa688a1077224a3 by org.apache.commons.codec.digest.DigestUtils
MD4: The MD4 method is not implemented. by org.apache.commons.codec.digest.DigestUtils
MD5: 2947f614c460347649185e62ee914eac by org.apache.commons.codec.digest.DigestUtils
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# 消息摘要算法--应用
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