android RSA加密解密

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最新推荐文章于 2024-07-21 11:25:24 发布

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本文链接：https://blog.youkuaiyun.com/fugang1230/article/details/79379490

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本文介绍了一个Android平台上的RSA加密解密功能模块。该模块实现了利用预定义的公钥和私钥对文本进行加密和解密的过程，并提供了具体的代码示例。

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本文主要是实现Android RSA加密解密功能，在网上参考了很多人提供的方法，自己改写成一个关于Android RSA加密解密文件的功能模块，方便项目上使用。

首先先确定公钥和私钥，在写死的情况下进行加密解密。

密钥可以用字符串写死，也可以保存到文件中放到assets文件夹中

具体代码如下：

MainActivity.java

package com.example.rsademo;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

import java.io.InputStream;
import java.security.PrivateKey;
import java.security.PublicKey;

public class MainActivity extends Activity implements OnClickListener
{
	private Button btn1, btn2;// 加密，解密
	private EditText et1, et2, et3;// 需加密的内容，加密后的内容，解密后的内容

	/* 密钥内容 base64 code */
	private static String PUCLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCfRTdcPIH10gT9f31rQuIInLwe"
			+ "\r" + "7fl2dtEJ93gTmjE9c2H+kLVENWgECiJVQ5sonQNfwToMKdO0b3Olf4pgBKeLThra" + "\r"
			+ "z/L3nYJYlbqjHC3jTjUnZc0luumpXGsox62+PuSGBlfb8zJO6hix4GV/vhyQVCpG" + "\r"
			+ "9aYqgE7zyTRZYX9byQIDAQAB" + "\r";
	private static String PRIVATE_KEY = "MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAJ9FN1w8gfXSBP1/"
			+ "\r" + "fWtC4gicvB7t+XZ20Qn3eBOaMT1zYf6QtUQ1aAQKIlVDmyidA1/BOgwp07Rvc6V/" + "\r"
			+ "imAEp4tOGtrP8vedgliVuqMcLeNONSdlzSW66alcayjHrb4+5IYGV9vzMk7qGLHg" + "\r"
			+ "ZX++HJBUKkb1piqATvPJNFlhf1vJAgMBAAECgYA736xhG0oL3EkN9yhx8zG/5RP/" + "\r"
			+ "WJzoQOByq7pTPCr4m/Ch30qVerJAmoKvpPumN+h1zdEBk5PHiAJkm96sG/PTndEf" + "\r"
			+ "kZrAJ2hwSBqptcABYk6ED70gRTQ1S53tyQXIOSjRBcugY/21qeswS3nMyq3xDEPK" + "\r"
			+ "XpdyKPeaTyuK86AEkQJBAM1M7p1lfzEKjNw17SDMLnca/8pBcA0EEcyvtaQpRvaL" + "\r"
			+ "n61eQQnnPdpvHamkRBcOvgCAkfwa1uboru0QdXii/gUCQQDGmkP+KJPX9JVCrbRt" + "\r"
			+ "7wKyIemyNM+J6y1ZBZ2bVCf9jacCQaSkIWnIR1S9UM+1CFE30So2CA0CfCDmQy+y" + "\r"
			+ "7A31AkB8cGFB7j+GTkrLP7SX6KtRboAU7E0q1oijdO24r3xf/Imw4Cy0AAIx4KAu" + "\r"
			+ "L29GOp1YWJYkJXCVTfyZnRxXHxSxAkEAvO0zkSv4uI8rDmtAIPQllF8+eRBT/deD" + "\r"
			+ "JBR7ga/k+wctwK/Bd4Fxp9xzeETP0l8/I+IOTagK+Dos8d8oGQUFoQJBAI4Nwpfo" + "\r"
			+ "MFaLJXGY9ok45wXrcqkJgM+SN6i8hQeujXESVHYatAIL/1DgLi+u46EFD69fw0w+" + "\r" + "c7o0HLlMsYPAzJw="
			+ "\r";

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initView();
	}

	private void initView()
	{
		btn1 = (Button) findViewById(R.id.btn1);
		btn2 = (Button) findViewById(R.id.btn2);
		btn1.setOnClickListener(this);
		btn2.setOnClickListener(this);

		et1 = (EditText) findViewById(R.id.et1);
		et2 = (EditText) findViewById(R.id.et2);
		et3 = (EditText) findViewById(R.id.et3);
	}

	@Override
	public void onClick(View v)
	{
		switch (v.getId())
		{
		// 加密
		case R.id.btn1:
			String source = et1.getText().toString().trim();
			try
			{
				// 从字符串中得到公钥
				PublicKey publicKey = RSAUtils.loadPublicKey(PUCLIC_KEY);
				// 从文件中得到公钥
				//InputStream inPublic = getResources().getAssets().open("rsa_public_key.pem");
				//PublicKey publicKey = RSAUtils.loadPublicKey(inPublic);
				// 加密
				byte[] encryptByte = RSAUtils.encryptData(source.getBytes(), publicKey);
				// 为了方便观察吧加密后的数据用base64加密转一下，要不然看起来是乱码,所以解密是也是要用Base64先转换
				String afterencrypt = Base64Utils.encode(encryptByte);
				et2.setText(afterencrypt);
				Log.e("rsa","密文："+afterencrypt);
			} catch (Exception e)
			{
				e.printStackTrace();
			}
			break;
		// 解密
		case R.id.btn2:
			String encryptContent = et2.getText().toString().trim();
			try
			{
				// 从字符串中得到私钥
				PrivateKey privateKey = RSAUtils.loadPrivateKey(PRIVATE_KEY);
				// 从文件中得到私钥
				//InputStream inPrivate = getResources().getAssets().open("pkcs8_rsa_private_key.pem");
				//PrivateKey privateKey = RSAUtils.loadPrivateKey(inPrivate);
				// 因为RSA加密后的内容经Base64再加密转换了一下，所以先Base64解密回来再给RSA解密
				byte[] decryptByte = RSAUtils.decryptData(Base64Utils.decode(encryptContent), privateKey);
				String decryptStr = new String(decryptByte);
				et3.setText(decryptStr);
			} catch (Exception e)
			{
				e.printStackTrace();
			}
			break;
		default:
			break;
		}
	}

}

RSAUtils.java

package com.example.rsademo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

/**
 * @author Mr.Zheng
 * @date 2014年8月22日 下午1:44:23
 */
public final class RSAUtils
{
	private static String RSA = "RSA";

	/**
	 * 随机生成RSA密钥对(默认密钥长度为1024)
	 * 
	 * @return
	 */
	public static KeyPair generateRSAKeyPair()
	{
		return generateRSAKeyPair(1024);
	}

	/**
	 * 随机生成RSA密钥对
	 * 
	 * @param keyLength
	 *            密钥长度，范围：512～2048<br>
	 *            一般1024
	 * @return
	 */
	public static KeyPair generateRSAKeyPair(int keyLength)
	{
		try
		{
			KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);
			kpg.initialize(keyLength);
			return kpg.genKeyPair();
		} catch (NoSuchAlgorithmException e)
		{
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 用公钥加密 <br>
	 * 每次加密的字节数，不能超过密钥的长度值减去11
	 * 
	 * @param data
	 *            需加密数据的byte数据
	 *            公钥
	 * @return 加密后的byte型数据
	 */
	public static byte[] encryptData(byte[] data, PublicKey publicKey)
	{
		try
		{
			Cipher cipher = Cipher.getInstance(RSA);
			// 编码前设定编码方式及密钥
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
			// 传入编码数据并返回编码结果
			return cipher.doFinal(data);
		} catch (Exception e)
		{
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 用私钥解密
	 * 
	 * @param encryptedData
	 *            经过encryptedData()加密返回的byte数据
	 * @param privateKey
	 *            私钥
	 * @return
	 */
	public static byte[] decryptData(byte[] encryptedData, PrivateKey privateKey)
	{
		try
		{
			Cipher cipher = Cipher.getInstance(RSA);
			cipher.init(Cipher.DECRYPT_MODE, privateKey);
			return cipher.doFinal(encryptedData);
		} catch (Exception e)
		{
			return null;
		}
	}

	/**
	 * 通过公钥byte[](publicKey.getEncoded())将公钥还原，适用于RSA算法
	 * 
	 * @param keyBytes
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws InvalidKeySpecException
	 */
	public static PublicKey getPublicKey(byte[] keyBytes) throws NoSuchAlgorithmException,
			InvalidKeySpecException
	{
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(RSA);
		PublicKey publicKey = keyFactory.generatePublic(keySpec);
		return publicKey;
	}

	/**
	 * 通过私钥byte[]将公钥还原，适用于RSA算法
	 * 
	 * @param keyBytes
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws InvalidKeySpecException
	 */
	public static PrivateKey getPrivateKey(byte[] keyBytes) throws NoSuchAlgorithmException,
			InvalidKeySpecException
	{
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(RSA);
		PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
		return privateKey;
	}

	/**
	 * 使用N、e值还原公钥
	 * 
	 * @param modulus
	 * @param publicExponent
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws InvalidKeySpecException
	 */
	public static PublicKey getPublicKey(String modulus, String publicExponent)
			throws NoSuchAlgorithmException, InvalidKeySpecException
	{
		BigInteger bigIntModulus = new BigInteger(modulus);
		BigInteger bigIntPrivateExponent = new BigInteger(publicExponent);
		RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);
		KeyFactory keyFactory = KeyFactory.getInstance(RSA);
		PublicKey publicKey = keyFactory.generatePublic(keySpec);
		return publicKey;
	}

	/**
	 * 使用N、d值还原私钥
	 * 
	 * @param modulus
	 * @param privateExponent
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws InvalidKeySpecException
	 */
	public static PrivateKey getPrivateKey(String modulus, String privateExponent)
			throws NoSuchAlgorithmException, InvalidKeySpecException
	{
		BigInteger bigIntModulus = new BigInteger(modulus);
		BigInteger bigIntPrivateExponent = new BigInteger(privateExponent);
		RSAPublicKeySpec keySpec = new RSAPublicKeySpec(bigIntModulus, bigIntPrivateExponent);
		KeyFactory keyFactory = KeyFactory.getInstance(RSA);
		PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
		return privateKey;
	}

	/**
	 * 从字符串中加载公钥
	 * 
	 * @param publicKeyStr
	 *            公钥数据字符串
	 * @throws Exception
	 *             加载公钥时产生的异常
	 */
	public static PublicKey loadPublicKey(String publicKeyStr) throws Exception
	{
		try
		{
			byte[] buffer = Base64Utils.decode(publicKeyStr);
			KeyFactory keyFactory = KeyFactory.getInstance(RSA);
			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
			return (RSAPublicKey) keyFactory.generatePublic(keySpec);
		} catch (NoSuchAlgorithmException e)
		{
			throw new Exception("无此算法");
		} catch (InvalidKeySpecException e)
		{
			throw new Exception("公钥非法");
		} catch (NullPointerException e)
		{
			throw new Exception("公钥数据为空");
		}
	}

	/**
	 * 从字符串中加载私钥<br>
	 * 加载时使用的是PKCS8EncodedKeySpec（PKCS#8编码的Key指令）。
	 * 
	 * @param privateKeyStr
	 * @return
	 * @throws Exception
	 */
	public static PrivateKey loadPrivateKey(String privateKeyStr) throws Exception
	{
		try
		{
			byte[] buffer = Base64Utils.decode(privateKeyStr);
			// X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
			PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
			KeyFactory keyFactory = KeyFactory.getInstance(RSA);
			return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
		} catch (NoSuchAlgorithmException e)
		{
			throw new Exception("无此算法");
		} catch (InvalidKeySpecException e)
		{
			throw new Exception("私钥非法");
		} catch (NullPointerException e)
		{
			throw new Exception("私钥数据为空");
		}
	}

	/**
	 * 从文件中输入流中加载公钥
	 * 
	 * @param in
	 *            公钥输入流
	 * @throws Exception
	 *             加载公钥时产生的异常
	 */
	public static PublicKey loadPublicKey(InputStream in) throws Exception
	{
		try
		{
			return loadPublicKey(readKey(in));
		} catch (IOException e)
		{
			throw new Exception("公钥数据流读取错误");
		} catch (NullPointerException e)
		{
			throw new Exception("公钥输入流为空");
		}
	}

	/**
	 * 从文件中加载私钥
	 *
	 *            私钥文件名
	 * @return 是否成功
	 * @throws Exception
	 */
	public static PrivateKey loadPrivateKey(InputStream in) throws Exception
	{
		try
		{
			return loadPrivateKey(readKey(in));
		} catch (IOException e)
		{
			throw new Exception("私钥数据读取错误");
		} catch (NullPointerException e)
		{
			throw new Exception("私钥输入流为空");
		}
	}

	/**
	 * 读取密钥信息
	 * 
	 * @param in
	 * @return
	 * @throws IOException
	 */
	private static String readKey(InputStream in) throws IOException
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(in));
		String readLine = null;
		StringBuilder sb = new StringBuilder();
		while ((readLine = br.readLine()) != null)
		{
			if (readLine.charAt(0) == '-')
			{
				continue;
			} else
			{
				sb.append(readLine);
				sb.append('\r');
			}
		}

		return sb.toString();
	}

	/**
	 * 打印公钥信息
	 * 
	 * @param publicKey
	 */
	public static void printPublicKeyInfo(PublicKey publicKey)
	{
		RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
		System.out.println("----------RSAPublicKey----------");
		System.out.println("Modulus.length=" + rsaPublicKey.getModulus().bitLength());
		System.out.println("Modulus=" + rsaPublicKey.getModulus().toString());
		System.out.println("PublicExponent.length=" + rsaPublicKey.getPublicExponent().bitLength());
		System.out.println("PublicExponent=" + rsaPublicKey.getPublicExponent().toString());
	}

	public static void printPrivateKeyInfo(PrivateKey privateKey)
	{
		RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;
		System.out.println("----------RSAPrivateKey ----------");
		System.out.println("Modulus.length=" + rsaPrivateKey.getModulus().bitLength());
		System.out.println("Modulus=" + rsaPrivateKey.getModulus().toString());
		System.out.println("PrivateExponent.length=" + rsaPrivateKey.getPrivateExponent().bitLength());
		System.out.println("PrivatecExponent=" + rsaPrivateKey.getPrivateExponent().toString());

	}

}

Base64Utils.java

package com.example.rsademo;

import java.io.UnsupportedEncodingException;

/**
 * fugang
 */
public class Base64Utils
{
	private static char[] base64EncodeChars = new char[]
	{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
			'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
			'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', '+', '/' };
	private static byte[] base64DecodeChars = new byte[]
	{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,
			54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
			12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
			30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
			-1, -1, -1 };

	/**
	 *加密
	 */
	public static String encode(byte[] data)
	{
		StringBuffer sb = new StringBuffer();
		int len = data.length;
		int i = 0;
		int b1, b2, b3;
		while (i < len)
		{
			b1 = data[i++] & 0xff;
			if (i == len)
			{
				sb.append(base64EncodeChars[b1 >>> 2]);
				sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
				sb.append("==");
				break;
			}
			b2 = data[i++] & 0xff;
			if (i == len)
			{
				sb.append(base64EncodeChars[b1 >>> 2]);
				sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
				sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
				sb.append("=");
				break;
			}
			b3 = data[i++] & 0xff;
			sb.append(base64EncodeChars[b1 >>> 2]);
			sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
			sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
			sb.append(base64EncodeChars[b3 & 0x3f]);
		}
		return sb.toString();
	}

	/**
	 * 解密
	 */
	public static byte[] decode(String str)
	{
		try
		{
			return decodePrivate(str);
		} catch (UnsupportedEncodingException e)
		{
			e.printStackTrace();
		}
		return new byte[]
		{};
	}

	private static byte[] decodePrivate(String str) throws UnsupportedEncodingException
	{
		StringBuffer sb = new StringBuffer();
		byte[] data = null;
		data = str.getBytes("US-ASCII");
		int len = data.length;
		int i = 0;
		int b1, b2, b3, b4;
		while (i < len)
		{

			do
			{
				b1 = base64DecodeChars[data[i++]];
			} while (i < len && b1 == -1);
			if (b1 == -1)
				break;

			do
			{
				b2 = base64DecodeChars[data[i++]];
			} while (i < len && b2 == -1);
			if (b2 == -1)
				break;
			sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

			do
			{
				b3 = data[i++];
				if (b3 == 61)
					return sb.toString().getBytes("iso8859-1");
				b3 = base64DecodeChars[b3];
			} while (i < len && b3 == -1);
			if (b3 == -1)
				break;
			sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

			do
			{
				b4 = data[i++];
				if (b4 == 61)
					return sb.toString().getBytes("iso8859-1");
				b4 = base64DecodeChars[b4];
			} while (i < len && b4 == -1);
			if (b4 == -1)
				break;
			sb.append((char) (((b3 & 0x03) << 6) | b4));
		}
		return sb.toString().getBytes("iso8859-1");
	}

}

布局文件activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.rsademo.MainActivity" >

    <EditText
        android:id="@+id/et1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="输入需加密的内容" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/btn1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="加密" />

        <Button
            android:id="@+id/btn2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解密" />
    </LinearLayout>

    <EditText
        android:id="@+id/et2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="加密后的内容" />

    <EditText
        android:id="@+id/et3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="解密后的内容" />

</LinearLayout>

demo下载链接：http://download.youkuaiyun.com/download/fugang1230/10259965