--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/five_ten_sg/connectbot/util/Encryptor.java	Thu May 22 10:41:19 2014 -0700
@@ -0,0 +1,189 @@
+/*
+ * ConnectBot: simple, powerful, open-source SSH client for Android
+ * Copyright 2007 Kenny Root, Jeffrey Sharkey
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.five_ten_sg.connectbot.util;
+
+/**
+ * This class is from:
+ *
+ * Encryptor.java
+ * Copyright 2008 Zach Scrivena
+ * zachscrivena@gmail.com
+ * http://zs.freeshell.org/
+ */
+
+import java.security.MessageDigest;
+import java.security.SecureRandom;
+import java.util.Arrays;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+
+/**
+ * Perform AES-128 encryption.
+ */
+public final class Encryptor {
+    /** name of the character set to use for converting between characters and bytes */
+    private static final String CHARSET_NAME = "UTF-8";
+
+    /** random number generator algorithm */
+    private static final String RNG_ALGORITHM = "SHA1PRNG";
+
+    /** message digest algorithm (must be sufficiently long to provide the key and initialization vector) */
+    private static final String DIGEST_ALGORITHM = "SHA-256";
+
+    /** key algorithm (must be compatible with CIPHER_ALGORITHM) */
+    private static final String KEY_ALGORITHM = "AES";
+
+    /** cipher algorithm (must be compatible with KEY_ALGORITHM) */
+    private static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding";
+
+
+    /**
+    * Private constructor that should never be called.
+    */
+    private Encryptor()
+    {}
+
+
+    /**
+    * Encrypt the specified cleartext using the given password.
+    * With the correct salt, number of iterations, and password, the decrypt() method reverses
+    * the effect of this method.
+    * This method generates and uses a random salt, and the user-specified number of iterations
+    * and password to create a 16-byte secret key and 16-byte initialization vector.
+    * The secret key and initialization vector are then used in the AES-128 cipher to encrypt
+    * the given cleartext.
+    *
+    * @param salt
+    *     salt that was used in the encryption (to be populated)
+    * @param iterations
+    *     number of iterations to use in salting
+    * @param password
+    *     password to be used for encryption
+    * @param cleartext
+    *     cleartext to be encrypted
+    * @return
+    *     ciphertext
+    * @throws Exception
+    *     on any error encountered in encryption
+    */
+    public static byte[] encrypt(
+        final byte[] salt,
+        final int iterations,
+        final String password,
+        final byte[] cleartext)
+    throws Exception {
+        /* generate salt randomly */
+        SecureRandom.getInstance(RNG_ALGORITHM).nextBytes(salt);
+        /* compute key and initialization vector */
+        final MessageDigest shaDigest = MessageDigest.getInstance(DIGEST_ALGORITHM);
+        byte[] pw = password.getBytes(CHARSET_NAME);
+
+        for (int i = 0; i < iterations; i++) {
+            /* add salt */
+            final byte[] salted = new byte[pw.length + salt.length];
+            System.arraycopy(pw, 0, salted, 0, pw.length);
+            System.arraycopy(salt, 0, salted, pw.length, salt.length);
+            Arrays.fill(pw, (byte) 0x00);
+            /* compute SHA-256 digest */
+            shaDigest.reset();
+            pw = shaDigest.digest(salted);
+            Arrays.fill(salted, (byte) 0x00);
+        }
+
+        /* extract the 16-byte key and initialization vector from the SHA-256 digest */
+        final byte[] key = new byte[16];
+        final byte[] iv = new byte[16];
+        System.arraycopy(pw, 0, key, 0, 16);
+        System.arraycopy(pw, 16, iv, 0, 16);
+        Arrays.fill(pw, (byte) 0x00);
+        /* perform AES-128 encryption */
+        final Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
+        cipher.init(
+            Cipher.ENCRYPT_MODE,
+            new SecretKeySpec(key, KEY_ALGORITHM),
+            new IvParameterSpec(iv));
+        Arrays.fill(key, (byte) 0x00);
+        Arrays.fill(iv, (byte) 0x00);
+        return cipher.doFinal(cleartext);
+    }
+
+
+    /**
+    * Decrypt the specified ciphertext using the given password.
+    * With the correct salt, number of iterations, and password, this method reverses the effect
+    * of the encrypt() method.
+    * This method uses the user-specified salt, number of iterations, and password
+    * to recreate the 16-byte secret key and 16-byte initialization vector.
+    * The secret key and initialization vector are then used in the AES-128 cipher to decrypt
+    * the given ciphertext.
+    *
+    * @param salt
+    *     salt to be used in decryption
+    * @param iterations
+    *     number of iterations to use in salting
+    * @param password
+    *     password to be used for decryption
+    * @param ciphertext
+    *     ciphertext to be decrypted
+    * @return
+    *     cleartext
+    * @throws Exception
+    *     on any error encountered in decryption
+    */
+    public static byte[] decrypt(
+        final byte[] salt,
+        final int iterations,
+        final String password,
+        final byte[] ciphertext)
+    throws Exception {
+        /* compute key and initialization vector */
+        final MessageDigest shaDigest = MessageDigest.getInstance(DIGEST_ALGORITHM);
+        byte[] pw = password.getBytes(CHARSET_NAME);
+
+        for (int i = 0; i < iterations; i++) {
+            /* add salt */
+            final byte[] salted = new byte[pw.length + salt.length];
+            System.arraycopy(pw, 0, salted, 0, pw.length);
+            System.arraycopy(salt, 0, salted, pw.length, salt.length);
+            Arrays.fill(pw, (byte) 0x00);
+            /* compute SHA-256 digest */
+            shaDigest.reset();
+            pw = shaDigest.digest(salted);
+            Arrays.fill(salted, (byte) 0x00);
+        }
+
+        /* extract the 16-byte key and initialization vector from the SHA-256 digest */
+        final byte[] key = new byte[16];
+        final byte[] iv = new byte[16];
+        System.arraycopy(pw, 0, key, 0, 16);
+        System.arraycopy(pw, 16, iv, 0, 16);
+        Arrays.fill(pw, (byte) 0x00);
+        /* perform AES-128 decryption */
+        final Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
+        cipher.init(
+            Cipher.DECRYPT_MODE,
+            new SecretKeySpec(key, KEY_ALGORITHM),
+            new IvParameterSpec(iv));
+        Arrays.fill(key, (byte) 0x00);
+        Arrays.fill(iv, (byte) 0x00);
+        return cipher.doFinal(ciphertext);
+    }
+}