<span style="font-size:14px;">为了更好的用户体验,移动APPclient一般都会将用户信息进行保存以便兴许能够自己主动登录.</span>

保存了用户信息便涉及到了安全问题.

解决办法大概有一下几种:

1.首先,假设client和服务端都是你来设计开发,那么有两种比較可靠的方案

A.client将passwordHash加密,登录成功后将hash值保存到Sqlite.服务端得到username和hash值,採用相同的算法对password进行Hash运算,然后和用户传来的hash值进行比較,一致则登录成功.更加可靠的是对password加盐加密.比如能够採用PBKDF2加盐加密.

<span style="font-size:14px;">public static String createHash(String password)
			throws NoSuchAlgorithmException, InvalidKeySpecException {
		return createHash(password.toCharArray());
	}

	/**
	 * Returns a salted PBKDF2 hash of the password.
	 * 
	 * @param password
	 *            the password to hash
	 * @return a salted PBKDF2 hash of the password
	 */
	public static String createHash(char[] password)
			throws NoSuchAlgorithmException, InvalidKeySpecException {
		// Generate a random salt
		SecureRandom random = new SecureRandom();
		byte[] salt = new byte[SALT_BYTE_SIZE];
		random.nextBytes(salt);

		// Hash the password
		byte[] hash = pbkdf2(password, salt, PBKDF2_ITERATIONS, HASH_BYTE_SIZE);
		return PBKDF2_ITERATIONS + ":" + toHex(salt) + ":" + toHex(hash);
	}</span>

1000为迭代的次数,后面各自是salt和hash值.

服务端得到这个字符串后,从中解析出迭代次数,salt,hash1值,然后採用相同的算法对数据库里面的password进行计算

	public static boolean validatePassword(String password, String correctHash)
			throws NoSuchAlgorithmException, InvalidKeySpecException {
		return validatePassword(password.toCharArray(), correctHash);
	}

	/**
	 * Validates a password using a hash.
	 * 
	 * @param password
	 *            the password to check
	 * @param correctHash
	 *            the hash of the valid password
	 * @return true if the password is correct, false if not
	 */
	public static boolean validatePassword(char[] password, String correctHash)
			throws NoSuchAlgorithmException, InvalidKeySpecException {
		// Decode the hash into its parameters
		String[] params = correctHash.split(":");
		int iterations = Integer.parseInt(params[ITERATION_INDEX]);
		byte[] salt = fromHex(params[SALT_INDEX]);
		byte[] hash = fromHex(params[PBKDF2_INDEX]);
		// Compute the hash of the provided password, using the same salt,
		// iteration count, and hash length
		byte[] testHash = pbkdf2(password, salt, iterations, hash.length);
		// Compare the hashes in constant time. The password is correct if
		// both hashes match.
		return slowEquals(hash, testHash);
	}

B.使用非对称加密算法对password进行加密.

1. client使用公钥加密password，得到加密串，然后将其发送到服务端．
2. 服务端使用私钥解密password。进行验证，
3. 登录成功后，client将加密串保存到本地，便于下次自己主动登录；

android中使用jni对字符串加解密实现分析

加盐password哈希：怎样正确使用