有没有很好的例子说明如何在 Android 上使用 AES 处理 加密和解密图像和其他文件?
You could use functions like these:
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(clear); return encrypted; } private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] decrypted = cipher.doFinal(encrypted); return decrypted; }
And invoke them like this:
ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); // bm is the bitmap object byte[] b = baos.toByteArray(); byte[] keyStart = "this is a key".getBytes(); KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(keyStart); kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); byte[] key = skey.getEncoded(); // encrypt byte[] encryptedData = encrypt(key,b); // decrypt byte[] decryptedData = decrypt(key,encryptedData);
This should work, I use similar code in a project right now.
import java.security.AlgorithmParameters; import java.security.SecureRandom; import java.security.spec.KeySpec; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.SecretKeySpec; class SecurityUtils { private static final byte[] salt = { (byte) 0xA4, (byte) 0x0B, (byte) 0xC8, (byte) 0x34, (byte) 0xD6, (byte) 0x95, (byte) 0xF3, (byte) 0x13 }; private static int BLOCKS = 128; public static byte[] encryptAES(String seed, String cleartext) throws Exception { byte[] rawKey = getRawKey(seed.getBytes("UTF8")); SecretKeySpec skeySpec = new SecretKeySpec(rawKey, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); return cipher.doFinal(cleartext.getBytes("UTF8")); } public static byte[] decryptAES(String seed, byte[] data) throws Exception { byte[] rawKey = getRawKey(seed.getBytes("UTF8")); SecretKeySpec skeySpec = new SecretKeySpec(rawKey, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.DECRYPT_MODE, skeySpec); return cipher.doFinal(data); } private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance("AES"); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG"); sr.setSeed(seed); kgen.init(BLOCKS, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; } private static byte[] pad(byte[] seed) { byte[] nseed = new byte[BLOCKS / 8]; for (int i = 0; i < BLOCKS / 8; i++) nseed[i] = 0; for (int i = 0; i < seed.length; i++) nseed[i] = seed[i]; return nseed; } public static byte[] encryptPBE(String password, String cleartext) throws Exception { SecretKeyFactory factory = SecretKeyFactory .getInstance("PBKDF2WithHmacSHA1"); KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 1024, 256); SecretKey tmp = factory.generateSecret(spec); SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES"); Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, secret); AlgorithmParameters params = cipher.getParameters(); byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV(); return cipher.doFinal(cleartext.getBytes("UTF-8")); } public static String decryptPBE(SecretKey secret, String ciphertext, byte[] iv) throws Exception { Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv)); return new String(cipher.doFinal(ciphertext.getBytes()), "UTF-8"); } }
If you are encrypting a text file, then the following test/sample may be useful. It does the following:
and lastly buffers it
// AESdemo public class AESdemo extends Activity { boolean encryptionIsOn = true; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_aesdemo); // needs <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> String homeDirName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + getPackageName(); File file = new File(homeDirName, "test.txt"); byte[] keyBytes = getKey("password"); try { File dir = new File(homeDirName); if (!dir.exists()) dir.mkdirs(); if (!file.exists()) file.createNewFile(); OutputStreamWriter osw; if (encryptionIsOn) { Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES"); IvParameterSpec ivParameterSpec = new IvParameterSpec(keyBytes); cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec); FileOutputStream fos = new FileOutputStream(file); CipherOutputStream cos = new CipherOutputStream(fos, cipher); osw = new OutputStreamWriter(cos, "UTF-8"); } else // not encryptionIsOn osw = new FileWriter(file); BufferedWriter out = new BufferedWriter(osw); out.write("This is a test\n"); out.close(); } catch (Exception e) { System.out.println("Encryption Exception "+e); } /////////////////////////////////// try { InputStreamReader isr; if (encryptionIsOn) { Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES"); IvParameterSpec ivParameterSpec = new IvParameterSpec(keyBytes); cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec); FileInputStream fis = new FileInputStream(file); CipherInputStream cis = new CipherInputStream(fis, cipher); isr = new InputStreamReader(cis, "UTF-8"); } else isr = new FileReader(file); BufferedReader in = new BufferedReader(isr); String line = in.readLine(); System.out.println("Text read: <"+line+">"); in.close(); } catch (Exception e) { System.out.println("Decryption Exception "+e); } } private byte[] getKey(String password) throws UnsupportedEncodingException { String key = ""; while (key.length() < 16) key += password; return key.substring(0, 16).getBytes("UTF-8"); } }
Old question but I upgrade the answers supporting Android prior and post 4.2 and considering all recent changes according to Android developers blog
Plus I leave a working example on my github repo.
import java.nio.charset.Charset; import java.security.AlgorithmParameters; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; /* * This software is provided 'as-is', without any express or implied * warranty. In no event will Google be held liable for any damages * arising from the use of this software. * * Permission is granted to anyone to use this software for any purpose, * including commercial applications, and to alter it and redistribute it * freely, as long as the origin is not misrepresented. * * @author: Ricardo Champa * */ public class MyCipher { private final static String ALGORITHM = "AES"; private String mySecret; public MyCipher(String mySecret){ this.mySecret = mySecret; } public MyCipherData encryptUTF8(String data){ try{ byte[] bytes = data.toString().getBytes("utf-8"); byte[] bytesBase64 = Base64.encodeBase64(bytes); return encrypt(bytesBase64); } catch(Exception e){ MyLogs.show(e.getMessage()); return null; } } public String decryptUTF8(byte[] encryptedData, IvParameterSpec iv){ try { byte[] decryptedData = decrypt(encryptedData, iv); byte[] decodedBytes = Base64.decodeBase64(decryptedData); String restored_data = new String(decodedBytes, Charset.forName("UTF8")); return restored_data; } catch (Exception e) { MyLogs.show(e.getMessage());; return null; } } //AES private MyCipherData encrypt(byte[] raw, byte[] clear) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, ALGORITHM); Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); //solved using PRNGFixes class cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] data = cipher.doFinal(clear); AlgorithmParameters params = cipher.getParameters(); byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV(); return new MyCipherData(data, iv); } private byte[] decrypt(byte[] raw, byte[] encrypted, IvParameterSpec iv) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, ALGORITHM); Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv); byte[] decrypted = cipher.doFinal(encrypted); return decrypted; } private byte[] getKey() throws Exception{ byte[] keyStart = this.mySecret.getBytes("utf-8"); KeyGenerator kgen = KeyGenerator.getInstance(ALGORITHM); SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto"); // if (android.os.Build.VERSION.SDK_INT >= 17) { // sr = SecureRandom.getInstance("SHA1PRNG", "Crypto"); // } else { // sr = SecureRandom.getInstance("SHA1PRNG"); // } sr.setSeed(keyStart); kgen.init(128, sr); // 192 and 256 bits may not be available SecretKey skey = kgen.generateKey(); byte[] key = skey.getEncoded(); return key; } //////////////////////////////////////////////////////////// private MyCipherData encrypt(byte[] data) throws Exception{ return encrypt(getKey(),data); } private byte[] decrypt(byte[] encryptedData, IvParameterSpec iv) throws Exception{ return decrypt(getKey(),encryptedData, iv); } }
Simple API to perform AES encryption on Android. This is the Android counterpart to the AESCrypt library Ruby and Obj-C (with the same defaults):
https://github.com/scottyab/AESCrypt-Android
To add bouncy castle to Android project: https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk16/1.45
Add this line in your Main Activity:
static { Security.addProvider(new BouncyCastleProvider()); }
public class AESHelper { private static final String TAG = "AESHelper"; public static byte[] encrypt(byte[] data, String initVector, String key) { try { IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8")); Cipher c = Cipher.getInstance("AES/CBC/PKCS5PADDING"); SecretKeySpec k = new SecretKeySpec(Base64.decode(key, Base64.DEFAULT), "AES"); c.init(Cipher.ENCRYPT_MODE, k, iv); return c.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return null; } public static byte[] decrypt(byte[] data, String initVector, String key) { try { IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8")); Cipher c = Cipher.getInstance("AES/CBC/PKCS5PADDING"); SecretKeySpec k = new SecretKeySpec(Base64.decode(key, Base64.DEFAULT), "AES"); c.init(Cipher.DECRYPT_MODE, k, iv); return c.doFinal(data); } catch (Exception e) { e.printStackTrace(); } return null; } public static String keyGenerator() throws NoSuchAlgorithmException { KeyGenerator keyGenerator = KeyGenerator.getInstance("AES"); keyGenerator.init(192); return Base64.encodeToString(keyGenerator.generateKey().getEncoded(), Base64.DEFAULT); } }
AES encrypt/decrypt in android
String encData= encrypt("keykey".getBytes("UTF-16LE"), ("0123000000000215").getBytes("UTF-16LE")); String decData= decrypt("keykey",Base64.decode(encData.getBytes("UTF-16LE"), Base64.DEFAULT));
encrypt function
private static String encrypt(byte[] key, byte[] clear) throws Exception { MessageDigest md = MessageDigest.getInstance("md5"); byte[] digestOfPassword = md.digest(key); SecretKeySpec skeySpec = new SecretKeySpec(digestOfPassword, "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(clear); return Base64.encodeToString(encrypted,Base64.DEFAULT); }
decrypt function
private static String decrypt(String key, byte[] encrypted) throws Exception { MessageDigest md = MessageDigest.getInstance("md5"); byte[] digestOfPassword = md.digest(key.getBytes("UTF-16LE")); SecretKeySpec skeySpec = new SecretKeySpec(digestOfPassword, "AES"); Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding"); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] decrypted = cipher.doFinal(encrypted); return new String(decrypted, "UTF-16LE"); }
AES encrypt/decrypt in c#
static void Main(string[] args) { string enc = encryptAES("0123000000000215", "keykey"); string dec = decryptAES(enc, "keykey"); Console.ReadKey(); }
public static string encryptAES(string input, string key) { var plain = Encoding.Unicode.GetBytes(input); // 128 bits AesCryptoServiceProvider provider = new AesCryptoServiceProvider(); provider.KeySize = 128; provider.Mode = CipherMode.ECB; provider.Padding = PaddingMode.PKCS7; provider.Key = CalculateMD5Hash(key); var enc = provider.CreateEncryptor().TransformFinalBlock(plain, 0, plain.Length); return Convert.ToBase64String(enc); }
public static string decryptAES(string encryptText, string key) { byte[] enc = Convert.FromBase64String(encryptText); // 128 bits AesCryptoServiceProvider provider = new AesCryptoServiceProvider(); provider.KeySize = 128; provider.Mode = CipherMode.ECB; provider.Padding = PaddingMode.PKCS7; provider.Key = CalculateMD5Hash(key); var dec = provider.CreateDecryptor().TransformFinalBlock(enc, 0, enc.Length); return Encoding.Unicode.GetString(dec); }
create md5
public static byte[] CalculateMD5Hash(string input) { MD5 md5 = MD5.Create(); byte[] inputBytes = Encoding.Unicode.GetBytes(input); return md5.ComputeHash(inputBytes); }
As mentioned by Nacho.L PBKDF2WithHmacSHA1 derivation is used as it is more secured.
import android.util.Base64; import java.security.NoSuchAlgorithmException; import java.security.spec.InvalidKeySpecException; import java.security.spec.KeySpec; import javax.crypto.Cipher; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.SecretKeySpec; public class AESEncyption { private static final int pswdIterations = 10; private static final int keySize = 128; private static final String cypherInstance = "AES/CBC/PKCS5Padding"; private static final String secretKeyInstance = "PBKDF2WithHmacSHA1"; private static final String plainText = "sampleText"; private static final String AESSalt = "exampleSalt"; private static final String initializationVector = "8119745113154120"; public static String encrypt(String textToEncrypt) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(getRaw(plainText, AESSalt), "AES"); Cipher cipher = Cipher.getInstance(cypherInstance); cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(initializationVector.getBytes())); byte[] encrypted = cipher.doFinal(textToEncrypt.getBytes()); return Base64.encodeToString(encrypted, Base64.DEFAULT); } public static String decrypt(String textToDecrypt) throws Exception { byte[] encryted_bytes = Base64.decode(textToDecrypt, Base64.DEFAULT); SecretKeySpec skeySpec = new SecretKeySpec(getRaw(plainText, AESSalt), "AES"); Cipher cipher = Cipher.getInstance(cypherInstance); cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(initializationVector.getBytes())); byte[] decrypted = cipher.doFinal(encryted_bytes); return new String(decrypted, "UTF-8"); } private static byte[] getRaw(String plainText, String salt) { try { SecretKeyFactory factory = SecretKeyFactory.getInstance(secretKeyInstance); KeySpec spec = new PBEKeySpec(plainText.toCharArray(), salt.getBytes(), pswdIterations, keySize); return factory.generateSecret(spec).getEncoded(); } catch (InvalidKeySpecException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return new byte[0]; } }
For AES/CBC/PKCS7 encryption/decryption, Just Copy and paste the following code and replace SecretKey and IV with your own.
SecretKey
IV
import java.io.UnsupportedEncodingException; import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import android.util.Base64; public class CryptoHandler { String SecretKey = "xxxxxxxxxxxxxxxxxxxx"; String IV = "xxxxxxxxxxxxxxxx"; private static CryptoHandler instance = null; public static CryptoHandler getInstance() { if (instance == null) { instance = new CryptoHandler(); } return instance; } public String encrypt(String message) throws NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, InvalidKeyException, UnsupportedEncodingException, InvalidAlgorithmParameterException { byte[] srcBuff = message.getBytes("UTF8"); //here using substring because AES takes only 16 or 24 or 32 byte of key SecretKeySpec skeySpec = new SecretKeySpec(SecretKey.substring(0,32).getBytes(), "AES"); IvParameterSpec ivSpec = new IvParameterSpec(IV.substring(0,16).getBytes()); Cipher ecipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); ecipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivSpec); byte[] dstBuff = ecipher.doFinal(srcBuff); String base64 = Base64.encodeToString(dstBuff, Base64.DEFAULT); return base64; } public String decrypt(String encrypted) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException { SecretKeySpec skeySpec = new SecretKeySpec(SecretKey.substring(0,32).getBytes(), "AES"); IvParameterSpec ivSpec = new IvParameterSpec(IV.substring(0,16).getBytes()); Cipher ecipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); ecipher.init(Cipher.DECRYPT_MODE, skeySpec, ivSpec); byte[] raw = Base64.decode(encrypted, Base64.DEFAULT); byte[] originalBytes = ecipher.doFinal(raw); String original = new String(originalBytes, "UTF8"); return original; } }
Here is simple code snippet working for AES Encryption and Decryption.
import android.util.Base64; import java.io.UnsupportedEncodingException; import java.nio.charset.StandardCharsets; import java.security.InvalidAlgorithmParameterException; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.security.spec.InvalidKeySpecException; import java.security.spec.KeySpec; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.SecretKeySpec; public class AESEncryptionClass { private static String INIT_VECTOR_PARAM = "#####"; private static String PASSWORD = "#####"; private static String SALT_KEY = "#####"; private static SecretKeySpec generateAESKey() throws NoSuchAlgorithmException, InvalidKeySpecException { // Prepare password and salt key. char[] password = new String(Base64.decode(PASSWORD, Base64.DEFAULT)).toCharArray(); byte[] salt = new String(Base64.decode(SALT_KEY, Base64.DEFAULT)).getBytes(StandardCharsets.UTF_8); // Create object of [Password Based Encryption Key Specification] with required iteration count and key length. KeySpec spec = new PBEKeySpec(password, salt, 64, 256); // Now create AES Key using required hashing algorithm. SecretKey key = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1").generateSecret(spec); // Get encoded bytes of secret key. byte[] bytesSecretKey = key.getEncoded(); // Create specification for AES Key. SecretKeySpec secretKeySpec = new SecretKeySpec(bytesSecretKey, "AES"); return secretKeySpec; } /** * Call this method to encrypt the readable plain text and get Base64 of encrypted bytes. */ public static String encryptMessage(String message) throws BadPaddingException, IllegalBlockSizeException, NoSuchPaddingException, NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeySpecException, InvalidAlgorithmParameterException, InvalidKeyException { byte[] initVectorParamBytes = new String(Base64.decode(INIT_VECTOR_PARAM, Base64.DEFAULT)).getBytes(StandardCharsets.UTF_8); Cipher encryptionCipherBlock = Cipher.getInstance("AES/CBC/PKCS5Padding"); encryptionCipherBlock.init(Cipher.ENCRYPT_MODE, generateAESKey(), new IvParameterSpec(initVectorParamBytes)); byte[] messageBytes = message.getBytes(); byte[] cipherTextBytes = encryptionCipherBlock.doFinal(messageBytes); String encryptedText = Base64.encodeToString(cipherTextBytes, Base64.DEFAULT); return encryptedText; } /** * Call this method to decrypt the Base64 of encrypted message and get readable plain text. */ public static String decryptMessage(String base64Cipher) throws BadPaddingException, IllegalBlockSizeException, NoSuchPaddingException, NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeySpecException, InvalidAlgorithmParameterException, InvalidKeyException { byte[] initVectorParamBytes = new String(Base64.decode(INIT_VECTOR_PARAM, Base64.DEFAULT)).getBytes(StandardCharsets.UTF_8); Cipher decryptionCipherBlock = Cipher.getInstance("AES/CBC/PKCS5Padding"); decryptionCipherBlock.init(Cipher.DECRYPT_MODE, generateAESKey(), new IvParameterSpec(initVectorParamBytes)); byte[] cipherBytes = Base64.decode(base64Cipher, Base64.DEFAULT); byte[] messageBytes = decryptionCipherBlock.doFinal(cipherBytes); String plainText = new String(messageBytes); return plainText; } }
Now, call encryptMessage() or decryptMessage() for desired AES Operation with required parameters. Also, handle the exceptions during AES operations.
Now, call encryptMessage() or decryptMessage() for desired AES Operation with required parameters.
encryptMessage()
decryptMessage()
AES
Also, handle the exceptions during AES operations.
Hope it helped...