$Salt = $_POST['Salt']; 
$Password = $Query_Results['Password'];

if ($salt == $Stored_Salt AND $Authorized_Password == $Password){
  //PErform a decryption of the stored results
   echo $Decrypted_TextField;
}

听起来你可能想要更多关于加密的背景知识,特别是DB加密选项(你没有提到数据存储,但有完全加密的MysqL和Postgres选项).一般来说,“滚动你自己”几乎总是一个坏主意,不幸的是,在mcrypt()和openssl _ *()函数之间,坦率地向新手提出了太多选项(比如将EBC和CBC同等地呈现)有效选项).虽然这个主题： https://security.stackexchange.com/questions/18197/why-shouldnt-we-roll-our-own主要讨论创建“新颖”加密原语的徒劳无益,但该原则也适用于实现应用程序和数据库级加密的天真尝试.

实际上,您可能需要处理的最具挑战性的事情是密码/密钥管理问题.下面的代码将所有责任都放在客户端(发件人)上 – 除非您保存提交的密码(这种方式违背了整个目的),如果用户忘记或以后无法提供密码,加密数据在数据库中将是不可恢复的. (并且,是的,如果你真的想要沿着牦牛剃须路径走下去,那么可以选择多键信封加密).

如果你存储密钥/密码服务器端,那么你最好只在对手的路径上设置一个小路障：如果她能设法读取你的密钥文件,她就可以检索数据.但最糟糕的是,通过在本地保存密码,您会给用户一种虚假的安全感,如果这是财务,健康或其他受保护的信息,您和您的组织就会承担这种责任的负担.

最后,这里有一个成熟的库：http://phpseclib.sourceforge.net/crypt/examples.html但是在我看来,它为新手用户提供了太多选项(例如,参见代码生成器中的默认EBC模式).对于密码散列,请在此处仔细查看PHPPass库：http://www.openwall.com/phpass/.

总而言之,这是一个简单的双向,相当强的加密,随机生成的初始化向量和盐,以及256位AES对称(例如,非公钥)密码的工作开始.测试OSX Lion& CentOS / Redhat 6.

祝好运！

//$message = escapeshellarg( $_POST['message'] );
$message = 'This is my very secret data SSN# 009-68-1234';  

// Set to some reasonable limIT for DB.
// Make sure to size DB column +60 chars 
$max_msg_size = 1000;
$message = substr($message,$max_msg_size);

// User's password (swap for actual form post)
//$password = escapeshellarg( $_POST['password'] );
$password = 'opensesame';

// Salt to add entropy to users' supplied passwords
// Make sure to add complexity/length requirements to users passwords!
// Note: This does not need to be kept secret
$salt = sha1(mt_rand());

// Initialization Vector,randoMLy generated and saved each time
// Note: This does not need to be kept secret
$iv = substr(sha1(mt_rand()),16);

echo "\n Password: $password \n Message: $message \n Salt: $salt \n IV: $iv\n";

$encrypted = openssl_encrypt(
  "$message",'aes-256-cbc',"$salt:$password",null,$iv
);

$msg_bundle = "$salt:$iv:$encrypted";
echo " Encrypted bundle = $msg_bundle \n\n ";

// Save it... (make sure to use bind VARiables/PRepared statements!)
/* db_write( "insert into sensitive_table encrypted_msg values (:msg_bundle)",$msg_bundle ); */

现在检索它：

//  Retrieve From DB... 

//$password = escapeshellarg( $_POST['password'] );
$password = 'opensesame';

// Swap with actual db retrieval code here
//$saved_bundle = db_read( "select encrypted_msg from sensitive_table" );
$saved_bundle = $msg_bundle;

// Parse iv and encrypted string segments
$components = explode( ':',$saved_bundle );;

var_dump($components);

$salt          = $components[0];
$iv            = $components[1];
$encrypted_msg = $components[2];

$decrypted_msg = openssl_decrypt(
  "$encrypted_msg",$iv
);

if ( $decrypted_msg === false ) {
  die("Unable to decrypt message! (check password) \n");
}

$msg = substr( $decrypted_msg,41 );
echo "\n Decrypted message: $decrypted_msg \n";

样本输出：

Password: opensesame 
 Message: This is my very secret data SSN# 009-68-1234 

 Salt: 3F12ce187d5c5bcc3b0d5aCF1e76fad8b684ff37 
 IV: 00c1d3b4c6a6f4c3 

 Encrypted bundle = 3f12ce187d5c5bcc3b0d5acf1e76fad8b684ff37:00c1d3b4c6a6f4c3:KB6k+GlM+0EHbETUgEe8Lck0nF5qBz+51wc5LtmS4XMOm0Pfyyr2PIXMVEyzs/41 

 array(3) {
  [0]=>
  string(40) "3f12ce187d5c5bcc3b0d5acf1e76fad8b684ff37"
  [1]=>
  string(16) "00c1d3b4c6a6f4c3"
  [2]=>
  string(64) "KB6k+GlM+0EHbETUgEe8Lck0nF5qBz+51wc5LtmS4XMOm0Pfyyr2PIXMVEyzs/41"
}

 Decrypted message: This is my very secret data SSN# 009-68-1234