-
Notifications
You must be signed in to change notification settings - Fork 10
/
KeyHelper.java
248 lines (206 loc) · 10.5 KB
/
KeyHelper.java
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
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
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
package com.allonsy.android.ftp;
import android.content.Context;
import android.content.SharedPreferences;
import android.security.KeyPairGeneratorSpec;
import android.security.keystore.KeyGenParameterSpec;
import android.security.keystore.KeyProperties;
import android.util.Base64;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.InvalidAlgorithmParameterException;
import java.security.Key;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import java.util.ArrayList;
import java.util.Calendar;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.security.auth.x500.X500Principal;
public class KeyHelper{
private static final String RSA_MODE = "RSA/ECB/PKCS1Padding";
private static final String AES_MODE_M = "AES/GCM/NoPadding";
private static final String KEY_ALIAS = "KEY";
private static final String AndroidKeyStore = "AndroidKeyStore";
public static final String SHARED_PREFENCE_NAME = "SAVED_TO_SHARED";
public static final String ENCRYPTED_KEY = "ENCRYPTED_KEY";
public static final String PUBLIC_IV = "PUBLIC_IV";
private KeyStore keyStore;
public KeyHelper(Context ctx) throws NoSuchPaddingException,NoSuchProviderException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, KeyStoreException, CertificateException, IOException {
this.generateEncryptKey(ctx);
this.generateRandomIV(ctx);
if(android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.M){
try{
this.generateAESKey(ctx);
} catch(Exception e){
e.printStackTrace();
}
}
}
private void generateEncryptKey(Context ctx) throws NoSuchProviderException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, KeyStoreException, CertificateException, IOException {
keyStore = KeyStore.getInstance(AndroidKeyStore);
keyStore.load(null);
if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M){
if (!keyStore.containsAlias(KEY_ALIAS)) {
KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, AndroidKeyStore);
keyGenerator.init(
new KeyGenParameterSpec.Builder(KEY_ALIAS,
KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
.setBlockModes(KeyProperties.BLOCK_MODE_GCM)
.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
.setRandomizedEncryptionRequired(false)
.build());
keyGenerator.generateKey();
}
} else{
if (!keyStore.containsAlias(KEY_ALIAS)) {
// Generate a key pair for encryption
Calendar start = Calendar.getInstance();
Calendar end = Calendar.getInstance();
end.add(Calendar.YEAR, 30);
KeyPairGeneratorSpec spec = new KeyPairGeneratorSpec.Builder(ctx)
.setAlias(KEY_ALIAS)
.setSubject(new X500Principal("CN=" + KEY_ALIAS))
.setSerialNumber(BigInteger.TEN)
.setStartDate(start.getTime())
.setEndDate(end.getTime())
.build();
KeyPairGenerator kpg = KeyPairGenerator.getInstance(KeyProperties.KEY_ALGORITHM_RSA, AndroidKeyStore);
kpg.initialize(spec);
kpg.generateKeyPair();
}
}
}
private byte[] rsaEncrypt(byte[] secret) throws Exception{
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry) keyStore.getEntry(KEY_ALIAS, null);
// Encrypt the text
Cipher inputCipher = Cipher.getInstance(RSA_MODE, "AndroidOpenSSL");
inputCipher.init(Cipher.ENCRYPT_MODE, privateKeyEntry.getCertificate().getPublicKey());
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
CipherOutputStream cipherOutputStream = new CipherOutputStream(outputStream, inputCipher);
cipherOutputStream.write(secret);
cipherOutputStream.close();
return outputStream.toByteArray();
}
private byte[] rsaDecrypt(byte[] encrypted) throws Exception {
KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(KEY_ALIAS, null);
Cipher output = Cipher.getInstance(RSA_MODE, "AndroidOpenSSL");
output.init(Cipher.DECRYPT_MODE, privateKeyEntry.getPrivateKey());
CipherInputStream cipherInputStream = new CipherInputStream(
new ByteArrayInputStream(encrypted), output);
ArrayList<Byte> values = new ArrayList<>();
int nextByte;
while ((nextByte = cipherInputStream.read()) != -1) {
values.add((byte)nextByte);
}
byte[] bytes = new byte[values.size()];
for(int i = 0; i < bytes.length; i++) {
bytes[i] = values.get(i).byteValue();
}
return bytes;
}
private void generateAESKey(Context context) throws Exception{
SharedPreferences pref = context.getSharedPreferences(SHARED_PREFENCE_NAME, Context.MODE_PRIVATE);
String enryptedKeyB64 = pref.getString(ENCRYPTED_KEY, null);
if (enryptedKeyB64 == null) {
byte[] key = new byte[16];
SecureRandom secureRandom = new SecureRandom();
secureRandom.nextBytes(key);
byte[] encryptedKey = rsaEncrypt(key);
enryptedKeyB64 = Base64.encodeToString(encryptedKey, Base64.DEFAULT);
SharedPreferences.Editor edit = pref.edit();
edit.putString(ENCRYPTED_KEY, enryptedKeyB64);
edit.apply();
}
}
private Key getAESKeyFromKS() throws NoSuchProviderException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, KeyStoreException, CertificateException, IOException, UnrecoverableKeyException {
keyStore = KeyStore.getInstance(AndroidKeyStore);
keyStore.load(null);
SecretKey key = (SecretKey)keyStore.getKey(KEY_ALIAS,null);
return key;
}
private Key getSecretKey(Context context) throws Exception{
SharedPreferences pref = context.getSharedPreferences(SHARED_PREFENCE_NAME, Context.MODE_PRIVATE);
String enryptedKeyB64 = pref.getString(ENCRYPTED_KEY, null);
byte[] encryptedKey = Base64.decode(enryptedKeyB64, Base64.DEFAULT);
byte[] key = rsaDecrypt(encryptedKey);
return new SecretKeySpec(key, "AES");
}
public String encrypt(Context context, String input) throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
Cipher c;
SharedPreferences pref = context.getSharedPreferences(SHARED_PREFENCE_NAME, Context.MODE_PRIVATE);
String publicIV = pref.getString(PUBLIC_IV, null);
if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M){
c = Cipher.getInstance(AES_MODE_M);
try{
c.init(Cipher.ENCRYPT_MODE, getAESKeyFromKS(), new GCMParameterSpec(128,Base64.decode(publicIV, Base64.DEFAULT)));
} catch(Exception e){
e.printStackTrace();
}
} else{
c = Cipher.getInstance(AES_MODE_M);
try{
c.init(Cipher.ENCRYPT_MODE, getSecretKey(context),new GCMParameterSpec(128,Base64.decode(publicIV, Base64.DEFAULT)));
} catch (Exception e){
e.printStackTrace();
}
}
byte[] encodedBytes = c.doFinal(input.getBytes("UTF-8"));
return Base64.encodeToString(encodedBytes, Base64.DEFAULT);
}
public String decrypt(Context context, String encrypted) throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
Cipher c;
SharedPreferences pref = context.getSharedPreferences(SHARED_PREFENCE_NAME, Context.MODE_PRIVATE);
String publicIV = pref.getString(PUBLIC_IV, null);
if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M){
c = Cipher.getInstance(AES_MODE_M);
try{
c.init(Cipher.DECRYPT_MODE, getAESKeyFromKS(), new GCMParameterSpec(128,Base64.decode(publicIV, Base64.DEFAULT)));
} catch(Exception e){
e.printStackTrace();
}
} else{
c = Cipher.getInstance(AES_MODE_M);
try{
c.init(Cipher.DECRYPT_MODE, getSecretKey(context), new GCMParameterSpec(128,Base64.decode(publicIV, Base64.DEFAULT)));
} catch (Exception e){
e.printStackTrace();
}
}
byte[] decodedValue = Base64.decode(encrypted.getBytes("UTF-8"), Base64.DEFAULT);
byte[] decryptedVal = c.doFinal(decodedValue);
return new String(decryptedVal);
}
public void generateRandomIV(Context ctx){
SharedPreferences pref = ctx.getSharedPreferences(SHARED_PREFENCE_NAME, Context.MODE_PRIVATE);
String publicIV = pref.getString(PUBLIC_IV, null);
if(publicIV == null){
SecureRandom random = new SecureRandom();
byte[] generated = random.generateSeed(12);
String generatedIVstr = Base64.encodeToString(generated, Base64.DEFAULT);
SharedPreferences.Editor edit = pref.edit();
edit.putString(PUBLIC_IV, generatedIVstr);
edit.apply();
}
}
private String getStringFromSharedPrefs(String key, Context ctx){
SharedPreferences prefs = ctx.getSharedPreferences("myPrefs", 0);
return prefs.getString(key, null);
}
}