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Added methods for handling encrypted file + iv content 

Improved IV generation
This commit is contained in:
Sam Tuke 2012-07-17 19:15:59 +01:00
parent 6af99f3a09
commit 283561823f
2 changed files with 75 additions and 103 deletions
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176
apps/files_encryption/lib/crypt.php
View File

@ -56,19 +56,13 @@ class Crypt {
*/
public static function encrypt( $plainContent, $iv, $passphrase = '' ) {
# TODO: Move these methods into a separate public class for app developers
$iv64 = base64_encode( $iv );
$raw = false; // true returns raw bytes, false returns base64
if ( $encryptedContent = openssl_encrypt( $plainContent, 'AES-256-OFB', $passphrase, $raw, $iv ) ) {
if ( $encryptedContent = openssl_encrypt( $plainContent, 'AES-128-CFB', $passphrase, false, $iv ) ) {
return $encryptedContent;
} else {
\OC_Log::write( 'Encrypted storage', 'Encryption (symmetric) of file failed' , \OC_Log::ERROR );
\OC_Log::write( 'Encrypted storage', 'Encryption (symmetric) of content failed' , \OC_Log::ERROR );
return false;
@ -82,20 +76,84 @@ class Crypt {
*/
public static function decrypt( $encryptedContent, $iv, $passphrase ) {
// $iv64 = base64_encode( $iv );
//
// $iv = base64_decode( $iv64 );
$raw = false; // true returns raw bytes, false returns base64
if ( $plainContent = openssl_decrypt( $encryptedContent, 'AES-256-OFB', $passphrase, $raw, $iv) ) {
if ( $plainContent = openssl_decrypt( $encryptedContent, 'AES-128-CFB', $passphrase, false, $iv ) ) {
return $plainContent;
} else {
\OC_Log::write( 'Encrypted storage', 'Decryption (symmetric) of file failed' , \OC_Log::ERROR );
\OC_Log::write( 'Encrypted storage', 'Decryption (symmetric) of content failed' , \OC_Log::ERROR );
return false;
}
}
/**
* @brief Creates symmetric keyfile content
* @param $plainContent content to be encrypted in keyfile
* @returns encrypted content combined with IV
* @note IV need not be specified, as it will be stored in the returned keyfile
* and remain accessible therein.
*/
public static function symmetricEncryptFileContent( $plainContent, $passphrase = '' ) {
if ( !$plainContent ) {
return false;
}
$random = openssl_random_pseudo_bytes( 13 );
$iv = substr( base64_encode( $random ), 0, -4 );
if ( $encryptedContent = self::encrypt( $plainContent, $iv, $passphrase ) ) {
$combinedKeyfile = $encryptedContent .= $iv;
return $combinedKeyfile;
} else {
\OC_Log::write( 'Encrypted storage', 'Encryption (symmetric) of keyfile content failed' , \OC_Log::ERROR );
return false;
}
}
/**
* @brief Decrypts keyfile content
* @param string $source
* @param string $target
* @param string $key the decryption key
*
* This function decrypts a file
*/
public static function symmetricDecryptFileContent( $keyfileContent, $passphrase = '' ) {
if ( !$keyfileContent ) {
return false;
}
$iv = substr( $keyfileContent, -16 );
$encryptedContent = substr( $keyfileContent, 0, -16 );
if ( $plainContent = self::decrypt( $encryptedContent, $iv, $passphrase ) ) {
return $plainContent;
} else {
\OC_Log::write( 'Encrypted storage', 'Decryption (symmetric) of keyfile content failed' , \OC_Log::ERROR );
return false;
@ -127,92 +185,6 @@ class Crypt {
}
public static function encryptFile( $source, $target, $key='') {
$handleread = fopen($source, "rb");
if($handleread!=FALSE) {
$handlewrite = fopen($target, "wb");
while (!feof($handleread)) {
$content = fread($handleread, 8192);
$enccontent=OC_CRYPT::encrypt( $content, $key);
fwrite($handlewrite, $enccontent);
}
fclose($handlewrite);
fclose($handleread);
}
}
/**
* @brief decryption of a file
* @param string $source
* @param string $target
* @param string $key the decryption key
*
* This function decrypts a file
*/
public static function decryptFile( $source, $target, $key='') {
$handleread = fopen($source, "rb");
if($handleread!=FALSE) {
$handlewrite = fopen($target, "wb");
while (!feof($handleread)) {
$content = fread($handleread, 8192);
$enccontent=OC_CRYPT::decrypt( $content, $key);
if(feof($handleread)){
$enccontent=rtrim($enccontent, "\0");
}
fwrite($handlewrite, $enccontent);
}
fclose($handlewrite);
fclose($handleread);
}
}
/**
* @brief Encrypts data in 8192 byte sized blocks
* @returns encrypted data
*/
public static function blockEncrypt( $data, $key = '' ){
$result = '';
while( strlen( $data ) ) {
// Encrypt byte block
$result .= self::encrypt( substr( $data, 0, 8192 ), $key );
$data = substr( $data, 8192 );
}
return $result;
}
/**
* decrypt data in 8192b sized blocks
*/
public static function blockDecrypt( $data, $key='', $maxLength = 0 ) {
$result = '';
while( strlen( $data ) ) {
$result .= self::decrypt( substr( $data, 0, 8192 ), $key );
$data = substr( $data,8192 );
}
if ( $maxLength > 0 ) {
return substr( $result, 0, $maxLength );
} else {
return rtrim( $result, "\0" );
}
}
/**
* @brief Generate a random key for symmetric encryption
* @returns $key Generated key

2
apps/files_encryption/lib/util.php
View File

@ -114,7 +114,7 @@ class Util {
# TODO: Use proper IV in encryption
// Encrypt private key with user pwd as passphrase
$encryptedPrivateKey = Crypt::encrypt( $keypair['privateKey'], 1234567890123456, $passphrase );
$encryptedPrivateKey = Crypt::createSymmetricKeyfile( $keypair['privateKey'], $passphrase );
// $iv = openssl_random_pseudo_bytes(16);
$this->view->file_put_contents( '/'. 'keypair'. '/' . $privateKeyFileName, $encryptedPrivateKey );