1，keystore帮助类

app/src/main/java/com/ervin/mvp/utils/KeyStoreEncryption.java

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+package com.ervin.mvp.utils;
+
+import android.content.Context;
+import android.security.KeyPairGeneratorSpec;
+import android.security.keystore.KeyProperties;
+import android.util.Base64;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.math.BigInteger;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.KeyPairGenerator;
+import java.security.KeyStore;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.interfaces.RSAPrivateKey;
+import java.security.interfaces.RSAPublicKey;
+import java.util.ArrayList;
+import java.util.Calendar;
+
+import javax.crypto.Cipher;
+import javax.crypto.CipherInputStream;
+import javax.crypto.CipherOutputStream;
+import javax.security.auth.x500.X500Principal;
+
+/**
+ * Created by Ervin on 2018/1/30.
+ *
+ * android keystore 特别适合用来存储运行时数据比如（账户密码，token），动态生成密钥，使用公钥给数据加密，用私钥解密
+ */
+
+public class KeyStoreEncryption {
+
+    public static void createNewKeys(String alias,Context context){
+
+        Calendar start = Calendar.getInstance();
+        Calendar end = Calendar.getInstance();
+        end.add(Calendar.YEAR, 1);
+        try {
+            KeyPairGeneratorSpec spec = new KeyPairGeneratorSpec.Builder(context)
+                    .setAlias(alias)
+                    .setSubject(new X500Principal("CN=Gyenno, OU=Gyenno, O=Gyenno, L=ShenZheng, ST=GuangDong, C=CN"))
+                    .setSerialNumber(BigInteger.ONE)
+                    .setStartDate(start.getTime())
+                    .setEndDate(end.getTime())
+                    .build();
+            KeyPairGenerator generator = KeyPairGenerator.getInstance(KeyProperties.KEY_ALGORITHM_EC, "AndroidKeyStore");
+            generator.initialize(spec);
+
+            generator.generateKeyPair();
+
+
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        } catch (NoSuchProviderException e) {
+            e.printStackTrace();
+        } catch (InvalidAlgorithmParameterException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * 加密
+     * @param alias
+     * @param data
+     */
+    public byte[]  encryptString(String alias,String data){
+        byte[] encryptByte = new byte[16];
+        try {
+            KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
+            keyStore.load(null);
+            KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(alias, null);
+            RSAPublicKey publicKey = (RSAPublicKey) privateKeyEntry.getCertificate().getPublicKey();
+
+
+            Cipher input = Cipher.getInstance("RSA/ECB/PKCS1Padding", "AndroidOpenSSL");
+            input.init(Cipher.ENCRYPT_MODE, publicKey);
+
+            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+            CipherOutputStream cipherOutputStream = new CipherOutputStream(
+                    outputStream, input);
+            cipherOutputStream.write(data.getBytes("UTF-8"));
+            cipherOutputStream.close();
+
+            encryptByte = outputStream.toByteArray();
+        } catch (Exception e) {
+
+        }
+        return encryptByte;
+    }
+
+    /**
+     * 解密
+     * @param alias
+     */
+    public String decryptString(String alias,String encryptData) {
+        String decryData = "";
+        try {
+            KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
+            keyStore.load(null);
+            KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(alias, null);
+            RSAPrivateKey privateKey = (RSAPrivateKey) privateKeyEntry.getPrivateKey();
+
+            Cipher output = Cipher.getInstance("RSA/ECB/PKCS1Padding", "AndroidOpenSSL");
+            output.init(Cipher.DECRYPT_MODE, privateKey);
+
+            CipherInputStream cipherInputStream = new CipherInputStream(
+                    new ByteArrayInputStream(Base64.decode(encryptData, Base64.DEFAULT)), 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();
+            }
+
+            decryData = new String(bytes, 0, bytes.length, "UTF-8");
+
+
+
+        } catch (Exception e) {
+
+        }
+        return decryData;
+    }
+}