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Add helper method for openssl_cipher_iv_length(). #152

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Merged
merged 1 commit into from
Dec 22, 2015
Merged

Add helper method for openssl_cipher_iv_length(). #152

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28 changes: 22 additions & 6 deletions src/Core.php
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Original file line number Diff line number Diff line change
Expand Up @@ -27,12 +27,7 @@ public static function incrementCounter($ctr, $inc, &$config)
{
static $ivsize = null;
if ($ivsize === null) {
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
if ($ivsize === false) {
throw new Ex\CannotPerformOperationException(
"Problem obtaining the correct nonce length."
);
}
$ivsize = self::cipherIvLength($config->cipherMethod());
}

if (self::ourStrlen($ctr) !== $ivsize) {
Expand Down Expand Up @@ -73,6 +68,27 @@ public static function incrementCounter($ctr, $inc, &$config)
return $ctr;
}

/**
* Returns the cipher initialization vector (iv) length.
*
* @param string $method
* @return int
* @throws Ex\CannotPerformOperationException
*/
public static function cipherIvLength($method)
{
self::ensureFunctionExists('openssl_cipher_iv_length');
$ivsize = \openssl_cipher_iv_length($method);

if ($ivsize === false || $ivsize <= 0) {
throw new Ex\CannotPerformOperationException(
'Could not get the IV length from OpenSSL'
);
}

return $ivsize;
}

/**
* Returns a random binary string of length $octets bytes.
*
Expand Down
24 changes: 3 additions & 21 deletions src/Crypto.php
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Original file line number Diff line number Diff line change
Expand Up @@ -105,13 +105,7 @@ public static function encrypt($plaintext, $key, $raw_binary = false)
);

// Generate a random initialization vector.
Core::ensureFunctionExists("openssl_cipher_iv_length");
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
if ($ivsize === false || $ivsize <= 0) {
throw new Ex\CannotPerformOperationException(
"Could not get the IV length from OpenSSL"
);
}
$ivsize = Core::cipherIvLength($config->cipherMethod());
$iv = Core::secureRandom($ivsize);

$ciphertext = $salt . $iv . self::plainEncrypt($plaintext, $ekey, $iv, $config);
Expand Down Expand Up @@ -210,13 +204,7 @@ public static function decrypt($ciphertext, $key, $raw_binary = false)
$ekey = Core::HKDF($config->hashFunctionName(), $key, $config->keyByteSize(), $config->encryptionInfoString(), $salt, $config);

// Extract the initialization vector from the ciphertext.
Core::EnsureFunctionExists("openssl_cipher_iv_length");
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
if ($ivsize === false || $ivsize <= 0) {
throw new Ex\CannotPerformOperationException(
"Could not get the IV length from OpenSSL"
);
}
$ivsize = Core::cipherIvLength($config->cipherMethod());
if (Core::ourStrlen($ciphertext) <= $ivsize) {
throw new Ex\InvalidCiphertextException(
"Ciphertext is too short."
Expand Down Expand Up @@ -302,13 +290,7 @@ public static function legacyDecrypt($ciphertext, $key)
);

// Extract the initialization vector from the ciphertext.
Core::EnsureFunctionExists("openssl_cipher_iv_length");
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
if ($ivsize === false || $ivsize <= 0) {
throw new Ex\CannotPerformOperationException(
"Could not get the IV length from OpenSSL"
);
}
$ivsize = Core::cipherIvLength($config->cipherMethod());
if (Core::ourStrlen($ciphertext) <= $ivsize) {
throw new Ex\InvalidCiphertextException(
"Ciphertext is too short."
Expand Down
10 changes: 2 additions & 8 deletions src/File.php
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Original file line number Diff line number Diff line change
Expand Up @@ -273,13 +273,7 @@ public static function encryptResource($inputHandle, $outputHandle, Key $key)
/**
* Generate a random initialization vector.
*/
Core::ensureFunctionExists("openssl_cipher_iv_length");
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
if ($ivsize === false || $ivsize <= 0) {
throw new Ex\CannotPerformOperationException(
'Improper IV size'
);
}
$ivsize = Core::cipherIvLength($config->cipherMethod());
$iv = Core::secureRandom($ivsize);

/**
Expand Down Expand Up @@ -459,7 +453,7 @@ public static function decryptResource($inputHandle, $outputHandle, Key $key)
*
* It should be the first N blocks of the file (N = 16)
*/
$ivsize = \openssl_cipher_iv_length($config->cipherMethod());
$ivsize = Core::cipherIvLength($config->cipherMethod());
$iv = self::readBytes($inputHandle, $ivsize);

// How much do we increase the counter after each buffered encryption to prevent nonce reuse
Expand Down