前言：
项目中除了登陆，支付等接口采用rsa非对称加密，之外的采用aes对称加密，今天我们来认识一下aes加密。
其他几种加密方式：
什么是aes加密？
高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。
接下来我们来实际看下具体怎么实现：
对于AesUtils类常量简介：
private final static String HEX = "0123456789ABCDEF"; private static final String CBC_PKCS5_PADDING = "AES/CBC/PKCS5Padding";//AES是加密方式 CBC是工作模式 PKCS5Padding是填充模式 private static final String AES = "AES";//AES 加密 private static final String SHA1PRNG="SHA1PRNG";//// SHA1PRNG 强随机种子算法, 要区别4.2以上版本的调用方法
如何生成一个随机Key？
/* * 生成随机数，可以当做动态的密钥 加密和解密的密钥必须一致，不然将不能解密 */ public static String generateKey() { try { SecureRandom localSecureRandom = SecureRandom.getInstance(SHA1PRNG); byte[] bytes_key = new byte[20]; localSecureRandom.nextBytes(bytes_key); String str_key = toHex(bytes_key); return str_key; } catch (Exception e) { e.printStackTrace(); } return null; }
Aes密钥处理
// 对密钥进行处理 private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance(AES); //for android SecureRandom sr = null; // 在4.2以上版本中，SecureRandom获取方式发生了改变 if (android.os.Build.VERSION.SDK_INT >= 17) { sr = SecureRandom.getInstance(SHA1PRNG, "Crypto"); } else { sr = SecureRandom.getInstance(SHA1PRNG); } // for Java // secureRandom = SecureRandom.getInstance(SHA1PRNG); sr.setSeed(seed); kgen.init(128, sr); //256 bits or 128 bits,192bits //AES中128位密钥版本有10个加密循环，192比特密钥版本有12个加密循环，256比特密钥版本则有14个加密循环。 SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; }
Aes加密过程
/* * 加密 */ public static String encrypt(String key, String cleartext) { if (TextUtils.isEmpty(cleartext)) { return cleartext; } try { byte[] result = encrypt(key, cleartext.getBytes()); return Base64Encoder.encode(result); } catch (Exception e) { e.printStackTrace(); } return null; } /* * 加密 */ private static byte[] encrypt(String key, byte[] clear) throws Exception { byte[] raw = getRawKey(key.getBytes()); SecretKeySpec skeySpec = new SecretKeySpec(raw, AES); Cipher cipher = Cipher.getInstance(CBC_PKCS5_PADDING); cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()])); byte[] encrypted = cipher.doFinal(clear); return encrypted; }
Aes解密过程
/* * 解密 */ public static String decrypt(String key, String encrypted) { if (TextUtils.isEmpty(encrypted)) { return encrypted; } try { byte[] enc = Base64Decoder.decodeToBytes(encrypted); byte[] result = decrypt(key, enc); return new String(result); } catch (Exception e) { e.printStackTrace(); } return null; } /* * 解密 */ private static byte[] decrypt(String key, byte[] encrypted) throws Exception { byte[] raw = getRawKey(key.getBytes()); SecretKeySpec skeySpec = new SecretKeySpec(raw, AES); Cipher cipher = Cipher.getInstance(CBC_PKCS5_PADDING); cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(new byte[cipher.getBlockSize()])); byte[] decrypted = cipher.doFinal(encrypted); return decrypted; }
二进制转字符
//二进制转字符 public static String toHex(byte[] buf) { if (buf == null) return ""; StringBuffer result = new StringBuffer(2 * buf.length); for (int i = 0; i < buf.length; i++) { appendHex(result, buf[i]); } return result.toString(); } private static void appendHex(StringBuffer sb, byte b) { sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f)); }
测试程序：
List<Person> personList = new ArrayList<>(); int testMaxCount = 1000;//测试的最大数据条数 //添加测试数据 for (int i = 0; i < testMaxCount; i++) { Person person = new Person(); person.setAge(i); person.setName(String.valueOf(i)); personList.add(person); } //FastJson生成json数据 String jsonData = JsonUtils.objectToJsonForFastJson(personList); Log.e("MainActivity", "AES加密前json数据 ---->" + jsonData); Log.e("MainActivity", "AES加密前json数据长度 ---->" + jsonData.length()); //生成一个动态key String secretKey = AesUtils.generateKey(); Log.e("MainActivity", "AES动态secretKey ---->" + secretKey); //AES加密 long start = System.currentTimeMillis(); String encryStr = AesUtils.encrypt(secretKey, jsonData); long end = System.currentTimeMillis(); Log.e("MainActivity", "AES加密耗时 cost time---->" + (end - start)); Log.e("MainActivity", "AES加密后json数据 ---->" + encryStr); Log.e("MainActivity", "AES加密后json数据长度 ---->" + encryStr.length()); //AES解密 start = System.currentTimeMillis(); String decryStr = AesUtils.decrypt(secretKey, encryStr); end = System.currentTimeMillis(); Log.e("MainActivity", "AES解密耗时 cost time---->" + (end - start)); Log.e("MainActivity", "AES解密后json数据 ---->" + decryStr);
运行耗时：
数据前后变化：
由此可见对称Aes效率还是比较高的
补充关于Base64Decoder类和Base64Encoder类
package com.whoislcj.testhttp.utils; import android.text.TextUtils; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.FilterInputStream; import java.io.IOException; import java.io.InputStream; public class Base64Decoder extends FilterInputStream { private static final char[] chars = { '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', '+', '/' }; // A mapping between char values and six-bit integers private static final int[] ints = new int[128]; static { for (int i = 0; i < 64; i++) { ints[chars[i]] = i; } } private int charCount; private int carryOver; /*** * Constructs a new Base64 decoder that reads input from the given * InputStream. * * @param in * the input stream */ private Base64Decoder(InputStream in) { super(in); } /*** * Returns the next decoded character from the stream, or -1 if end of * stream was reached. * * @return the decoded character, or -1 if the end of the input stream is * reached * @exception IOException * if an I/O error occurs */ public int read() throws IOException { // Read the next non-whitespace character int x; do { x = in.read(); if (x == -1) { return -1; } } while (Character.isWhitespace((char) x)); charCount++; // The '=' sign is just padding if (x == '=') { return -1; // effective end of stream } // Convert from raw form to 6-bit form x = ints[x]; // Calculate which character we're decoding now int mode = (charCount - 1) % 4; // First char save all six bits, go for another if (mode == 0) { carryOver = x & 63; return read(); } // Second char use previous six bits and first two new bits, // save last four bits else if (mode == 1) { int decoded = ((carryOver << 2) + (x >> 4)) & 255; carryOver = x & 15; return decoded; } // Third char use previous four bits and first four new bits, // save last two bits else if (mode == 2) { int decoded = ((carryOver << 4) + (x >> 2)) & 255; carryOver = x & 3; return decoded; } // Fourth char use previous two bits and all six new bits else if (mode == 3) { int decoded = ((carryOver << 6) + x) & 255; return decoded; } return -1; // can't actually reach this line } /*** * Reads decoded data into an array of bytes and returns the actual number * of bytes read, or -1 if end of stream was reached. * * @param buf * the buffer into which the data is read * @param off * the start offset of the data * @param len * the maximum number of bytes to read * @return the actual number of bytes read, or -1 if the end of the input * stream is reached * @exception IOException * if an I/O error occurs */ public int read(byte[] buf, int off, int len) throws IOException { if (buf.length < (len + off - 1)) { throw new IOException("The input buffer is too small: " + len + " bytes requested starting at offset " + off + " while the buffer " + " is only " + buf.length + " bytes long."); } // This could of course be optimized int i; for (i = 0; i < len; i++) { int x = read(); if (x == -1 && i == 0) { // an immediate -1 returns -1 return -1; } else if (x == -1) { // a later -1 returns the chars read so far break; } buf[off + i] = (byte) x; } return i; } /*** * Returns the decoded form of the given encoded string, as a String. Note * that not all binary data can be represented as a String, so this method * should only be used for encoded String data. Use decodeToBytes() * otherwise. * * @param encoded * the string to decode * @return the decoded form of the encoded string */ public static String decode(String encoded) { if (TextUtils.isEmpty(encoded)) { return ""; } return new String(decodeToBytes(encoded)); } /*** * Returns the decoded form of the given encoded string, as bytes. * * @param encoded * the string to decode * @return the decoded form of the encoded string */ public static byte[] decodeToBytes(String encoded) { byte[] bytes = encoded.getBytes(); Base64Decoder in = new Base64Decoder(new ByteArrayInputStream(bytes)); ByteArrayOutputStream out = new ByteArrayOutputStream((int) (bytes.length * 0.75)); try { byte[] buf = new byte[4 * 1024]; // 4K buffer int bytesRead; while ((bytesRead = in.read(buf)) != -1) { out.write(buf, 0, bytesRead); } return out.toByteArray(); } catch (IOException e) { throw new RuntimeException(e); } finally { try { in.close(); } catch (IOException e) { throw new RuntimeException(e); } try { out.close(); } catch (IOException e) { throw new RuntimeException(e); } } } }
package com.whoislcj.testhttp.utils; import java.io.ByteArrayOutputStream; import java.io.FilterOutputStream; import java.io.IOException; import java.io.OutputStream; public class Base64Encoder extends FilterOutputStream { private static final char[] chars = { '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 int charCount; private int carryOver; // 是否每76字节换行 private boolean isWrapBreak = true; /*** * Constructs a new Base64 encoder that writes output to the given * OutputStream. * * @param out * the output stream */ private Base64Encoder(OutputStream out) { super(out); } /*** * Constructs a new Base64 encoder that writes output to the given * OutputStream. * * @param out * the output stream */ private Base64Encoder(OutputStream out, boolean isWrapBreak) { this(out); this.isWrapBreak = isWrapBreak; } /*** * Writes the given byte to the output stream in an encoded form. * * @exception IOException * if an I/O error occurs */ public void write(int b) throws IOException { // Take 24-bits from three octets, translate into four encoded chars // Break lines at 76 chars // If necessary, pad with 0 bits on the right at the end // Use = signs as padding at the end to ensure encodedLength % 4 == 0 // Remove the sign bit, // thanks to Christian Schweingruber <chrigu@lorraine.ch> if (b < 0) { b += 256; } // First byte use first six bits, save last two bits if (charCount % 3 == 0) { int lookup = b >> 2; carryOver = b & 3; // last two bits out.write(chars[lookup]); } // Second byte use previous two bits and first four new bits, // save last four bits else if (charCount % 3 == 1) { int lookup = ((carryOver << 4) + (b >> 4)) & 63; carryOver = b & 15; // last four bits out.write(chars[lookup]); } // Third byte use previous four bits and first two new bits, // then use last six new bits else if (charCount % 3 == 2) { int lookup = ((carryOver << 2) + (b >> 6)) & 63; out.write(chars[lookup]); lookup = b & 63; // last six bits out.write(chars[lookup]); carryOver = 0; } charCount++; // Add newline every 76 output chars (that's 57 input chars) if (this.isWrapBreak && charCount % 57 == 0) { out.write(' '); } } /*** * Writes the given byte array to the output stream in an encoded form. * * @param buf * the data to be written * @param off * the start offset of the data * @param len * the length of the data * @exception IOException * if an I/O error occurs */ public void write(byte[] buf, int off, int len) throws IOException { // This could of course be optimized for (int i = 0; i < len; i++) { write(buf[off + i]); } } /*** * Closes the stream, this MUST be called to ensure proper padding is * written to the end of the output stream. * * @exception IOException * if an I/O error occurs */ public void close() throws IOException { // Handle leftover bytes if (charCount % 3 == 1) { // one leftover int lookup = (carryOver << 4) & 63; out.write(chars[lookup]); out.write('='); out.write('='); } else if (charCount % 3 == 2) { // two leftovers int lookup = (carryOver << 2) & 63; out.write(chars[lookup]); out.write('='); } super.close(); } /*** * Returns the encoded form of the given unencoded string.<br> * 默认是否每76字节换行 * * @param bytes * the bytes to encode * @return the encoded form of the unencoded string * @throws IOException */ public static String encode(byte[] bytes) { return encode(bytes, true); } /*** * Returns the encoded form of the given unencoded string. * * @param bytes * the bytes to encode * @param isWrapBreak * 是否每76字节换行 * @return the encoded form of the unencoded string * @throws IOException */ public static String encode(byte[] bytes, boolean isWrapBreak) { ByteArrayOutputStream out = new ByteArrayOutputStream((int) (bytes.length * 1.4)); Base64Encoder encodedOut = new Base64Encoder(out, isWrapBreak); try { encodedOut.write(bytes); } catch (IOException e) { throw new RuntimeException(e); } finally { try { encodedOut.close(); } catch (IOException e) { throw new RuntimeException(e); } } return out.toString(); } // public static void main(String[] args) throws Exception { // if (args.length != 1) { // System.err // .println("Usage: java com.oreilly.servlet.Base64Encoder fileToEncode"); // return; // } // Base64Encoder encoder = null; // BufferedInputStream in = null; // try { // encoder = new Base64Encoder(System.out); // in = new BufferedInputStream(new FileInputStream(args[0])); // // byte[] buf = new byte[4 * 1024]; // 4K buffer // int bytesRead; // while ((bytesRead = in.read(buf)) != -1) { // encoder.write(buf, 0, bytesRead); // } // } finally { // if (in != null) // in.close(); // if (encoder != null) // encoder.close(); // } // } }