对称性加密算法"/>
RSA被称为非对称性加密算法
laiyuan:
概述
RSA被称为非对称性加密算法,意思就是加密和解密用的不是同一份密钥。RSA算法的密钥分为公钥和私钥,两者内容不同,用途也不同。公钥用于加密,一般交给客户端使用;私钥用于解密,一般由服务器管理。反过来,对称性加密算法,指的就是用同一份密钥进行加密解密了,比如DES加密算法。
RSA算法实现
一、生成密钥对
在使用RSA加密解密之前,首先要生成密钥对。RSA算法的密钥可以通过两个途径生成,一是借助openssl命令终端,二是使用代码生成。
1、Openssl生成密钥对
首先你得安装Openssl,这里就不再叙述如何安装Openssl了,正好给你个机会去撩一下度娘。
第一步,生成私钥。现在我们找到openssl安装目录的bin文件夹,双击打开openssl.exe,输入命令
[java] view plain copy- genrsa -out rsa_private_key.pem 1024
在openssl.exe的同级目录下可以找到生成的私钥文件rsa_private_key.pem,打开后看到的内容类似下面
- -----BEGIN RSA PRIVATE KEY-----
- MIICWwIBAAKBgQC7yil5BUsHf+PdPl9fzdr3FNyrXDPJwV8Vfk3hCsiqs3YzHYjE
- YpHZiaF8dg9wB/aqmKRA0KFH2eTv++GNf0fAtdfbZUeq1Y79BDs23kSoS6g0Xe8m
- D76A2oD+G0o/llsBjpmWViFaCre0uALyOwd412pU7yj+IJU+JlNlxLapNwIDAQAB
- AoGAH0C+9DgwS3g6WQjXYJ9m8LYVH6PBrrMy+uXBWlGsIdSqOEmTCHQLJ/Qi3w7a
- 9N8uayfqNitCnC2kT1hRKnZjX2Miy0LCfLsH6REV1NUgSmC7lr/TKkq9Hnvp1Y0H
- bi7u5ux6QUzY8Yb7f6go7rAk764EikV8QeuRKsQP0jaPIckCQQDg8yyWlsWL298C
- sn15tQAqmNI8kWpmOmZuvNE0oTzodsMCfi0K3e5c3KtHUgso1hPWTxJguRpWw1jS
- 4NsoYWJTAkEA1bXlP1vHF4DW9XjoE/VSb3ReUXvqCx96IrdxcKXKOPrNsGOpKBkL
- 3x74jImXjIiSEe4ePvOHsQ5HgB9scPlJDQJATcrKuKkbV+qJjN09F0HI9PI0gk2n
- hgLcOZ+CmbjI33typQINgZyOOf72HIv63/xoj8x4hop82VRk+0hXgfdrkQJABQFo
- qC4/IIbNAhzd2rHRR3kDSIdNeQs4sh1307qeXO1K6gm7iYvkoko4ahpC6XC9cxwP
- q0vK7tO1ywNxZ8f+9QJAO2sXpLl4G/I0xrizv9Yoe7MON+8CsMXIUb0Swf3Q4Bbj
- YNWXYD1BBa1qkIQU48dLgbJU24Abzl57nkSN/nns4A==
- -----END RSA PRIVATE KEY-----
请忽略带有虚线的第一行和最后一行,中间的内容就是我们的私钥了。
第二步,生成公钥。继续在openssl终端窗口输入命令:
[java] view plain copy- rsa -in rsa_private_key.pem -out rsa_public_key.pem -pubout
这里根据私钥数据,生成了公钥,同样也是保存在openssl.exe同级目录下,打开看里面的内容:
- -----BEGIN PUBLIC KEY-----
- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC7yil5BUsHf+PdPl9fzdr3FNyr
- XDPJwV8Vfk3hCsiqs3YzHYjEYpHZiaF8dg9wB/aqmKRA0KFH2eTv++GNf0fAtdfb
- ZUeq1Y79BDs23kSoS6g0Xe8mD76A2oD+G0o/llsBjpmWViFaCre0uALyOwd412pU
- 7yj+IJU+JlNlxLapNwIDAQAB
- -----END PUBLIC KEY-----
到这里,密钥对基本生成了,但是这个密钥对的私钥无法在代码中直接使用,需要对私钥进行PKCS#8编码,继续敲命令: [java] view plain copy
- pkcs8 -topk8 -in rsa_private_key.pem -out pkcs8_rsa_private_key.pem -nocrypt
同样在openssl.exe同级目录下找到文件pkcs8_rsa_private_key.pem,这里就是我们最终需要的私钥了。
下面可以看到内容跟rsa_private_key.pem里面的内容是不一样的:
[java] view plain copy- -----BEGIN PRIVATE KEY-----
- MIICdQIBADANBgkqhkiG9w0BAQEFAASCAl8wggJbAgEAAoGBALvKKXkFSwd/490+
- X1/N2vcU3KtcM8nBXxV+TeEKyKqzdjMdiMRikdmJoXx2D3AH9qqYpEDQoUfZ5O/7
- 4Y1/R8C119tlR6rVjv0EOzbeRKhLqDRd7yYPvoDagP4bSj+WWwGOmZZWIVoKt7S4
- AvI7B3jXalTvKP4glT4mU2XEtqk3AgMBAAECgYAfQL70ODBLeDpZCNdgn2bwthUf
- o8GuszL65cFaUawh1Ko4SZMIdAsn9CLfDtr03y5rJ+o2K0KcLaRPWFEqdmNfYyLL
- QsJ8uwfpERXU1SBKYLuWv9MqSr0ee+nVjQduLu7m7HpBTNjxhvt/qCjusCTvrgSK
- RXxB65EqxA/SNo8hyQJBAODzLJaWxYvb3wKyfXm1ACqY0jyRamY6Zm680TShPOh2
- wwJ+LQrd7lzcq0dSCyjWE9ZPEmC5GlbDWNLg2yhhYlMCQQDVteU/W8cXgNb1eOgT
- 9VJvdF5Re+oLH3oit3Fwpco4+s2wY6koGQvfHviMiZeMiJIR7h4+84exDkeAH2xw
- +UkNAkBNysq4qRtX6omM3T0XQcj08jSCTaeGAtw5n4KZuMjfe3KlAg2BnI45/vYc
- i/rf/GiPzHiGinzZVGT7SFeB92uRAkAFAWioLj8ghs0CHN3asdFHeQNIh015Cziy
- HXfTup5c7UrqCbuJi+SiSjhqGkLpcL1zHA+rS8ru07XLA3Fnx/71AkA7axekuXgb
- 8jTGuLO/1ih7sw437wKwxchRvRLB/dDgFuNg1ZdgPUEFrWqQhBTjx0uBslTbgBvO
- XnueRI3+eezg
- -----END PRIVATE KEY-----
2、代码生成密钥对
除了上面的openssl方法可以生成密钥对外,使用代码也是可以生成的,具体的代码如下:
[java] view plain copy- 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;
- }
- }
keyLength范围512~2048, 一般取1024,其他值本人没尝试过,有探索精神的可以自行更改。
通过keyPair.getPublic().getEncoded(),keyPair.getPrivate().getEncoded()分别获取公钥、私钥的字节码。
为了更直观一点,可以通过Base64编码把字节码转为可读的字符串保存起来 Base64Utils.encode(rsaKeyPair.getPublic().getEncoded());
二、RSA加密解密代码实现
废话少说,赶着回家吃饭,上代码:
- package com.yspay.sdk.util;
- import java.io.BufferedReader;
- import java.io.ByteArrayOutputStream;
- 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;
- /**
- *
- */
- 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除以 8 再减去 11,所以采取分段加密的方式规避
- *
- * @param data 需加密数据的byte数据
- * @param publicKey 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);
- RSAPublicKey rsaPublicKey = (RSAPublicKey) publicKey;
- // 模长
- int keyLen = rsaPublicKey.getModulus().bitLength() / 8;
- int maxEncryptBlock = keyLen - 11;
- //如果明文长度大于模长-11则要分组加密
- int inputLen = data.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] temp;
- int i = 0;
- // 对数据分段加密
- while (inputLen - offSet > 0) {
- if (inputLen - offSet > maxEncryptBlock) {
- temp = cipher.doFinal(data, offSet, maxEncryptBlock);
- } else {
- temp = cipher.doFinal(data, offSet, inputLen - offSet);
- }
- out.write(temp, 0, temp.length);
- i++;
- offSet = i * maxEncryptBlock;
- }
- byte[] encryptedData = out.toByteArray();
- out.close();
- // 传入编码数据并返回编码结果
- return encryptedData;
- } 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);
- RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) privateKey;
- // 模长
- int keyLen = rsaPrivateKey.getModulus().bitLength() / 8;
- int maxDecryptBlock = keyLen;//不用减11
- //如果密文长度大于模长则要分组解密
- int inputLen = encryptedData.length;
- ByteArrayOutputStream out = new ByteArrayOutputStream();
- int offSet = 0;
- byte[] temp;
- int i = 0;
- // 对数据分段解密
- while (inputLen - offSet > 0) {
- if (inputLen - offSet > maxDecryptBlock) {
- temp = cipher.doFinal(encryptedData, offSet, maxDecryptBlock);
- } else {
- temp = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
- }
- out.write(temp, 0, temp.length);
- i++;
- offSet = i * maxDecryptBlock;
- }
- byte[] decryptedData = out.toByteArray();
- out.close();
- return decryptedData;
- } catch (Exception e)
- {
- e.printStackTrace();
- 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
- * @param in
- * @return 私钥
- * @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();
- }
- }
Base64编码工具可以使用系统自带的android.util.Base64,也可以自己实现,以下是 从别处扣来的代码:
- package com.yspay.sdk.util;
- import java.io.UnsupportedEncodingException;
- /**
- * Created by MPC on 2017/5/24.
- */
- 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
- *
- * @param data
- * @return
- */
- 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
- *
- * @param str
- * @return
- */
- 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");
public static void main(String[] args) {RSAPublicKey publicKey = RSAUtils.getDefaultPublicKey();String modulus = new String(Hex.encodeHex(publicKey.getModulus().toByteArray()));String exponent = new String(Hex.encodeHex(publicKey.getPublicExponent().toByteArray()));System.out.println("modulus:"+modulus);System.out.println("exponent:"+exponent);String plaintext = "111111";String encrypttext = encryptString(plaintext);System.out.println(encrypttext);String decrypttext = decryptString(encrypttext);System.out.println(decrypttext);}
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RSA被称为非对称性加密算法
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