Cryptographic protection of databases, mailinglists, memberslists.

A straightforward protection scheme: One-way hash function with symmetric encryption.

1. Encrypt the index field with a one-way hash function

2. Use the value of step 1 as the cipher key to encrypt the data fields.

Symmetric encryption algorithim — the same cipher key is used to encrypt and decrypt data

Searching the database

Look for the hashed value in the index field of the database and for each matching entry decrypt the data fields using the index field as the cipher key.

Insert a record of John Doe in an encrypted database.

<?php

        require_once("Crypt/Blowfish.php"); // a Pear class  http://pear.php.net

        $aRecord['email']       =       "johndoe@anisp.localhost"; // The Primary key
        $aRecord['name']        =       "John Doe";
        $aRecord['creditnr']    =       "0192733652342" ;

        // crypt - one-way encryption
        $cipher_key = crypt( $aRecord['email'] , "A_SECRET_COMPANY_SALT");

        $bf = new Crypt_Blowfish('ecb');
        $bf->setKey( $cipher_key );

        // crypt_blowfish symmetric encryption to encrypt the data
        $aRecord['email']       = $bf->encrypt( $aRecord['email'] );
        $aRecord['name']        = $bf->encrypt( $aRecord['name'] );
        $aRecord['creditnr']    = $bf->encrypt( $aRecord['creditnr'] );

        $result = sqlInsert( $aRecord ) ;
?>

Get the encrypted record of user John Doe and decrypt the data.

<?php

        require_once("Crypt/Blowfish.php");  // a Pear class http://pear.php.net

        $primary_key = "johndoe@anisp.localhost";

        // crypt - one-way encryption
        $cipher_key = crypt(  $primary_key , "A_SECRET_COMPANY_SALT");

        $bf = new Crypt_Blowfish('ecb');
        $bf->setKey( $cipher_key );

        // crypt_blowfish symmetric encryption to ecrypt the primary key for a sql select
        $select_key = $bf->encrypt(  $primary_key ) ;

        $aRecord = sqlSelectWithPKEY( $select_key );

        // crypt_blowfish symmetric encryption to decrypt the data
        $aRecord['email']       = $bf->decrypt( $aRecord['email'] );
        $aRecord['name']        = $bf->decrypt( $aRecord['name'] );
        $aRecord['creditnr']    = $bf->decrypt( $aRecord['creditnr'] );
?>

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