PHP 7.1.20 Released


(PHP 4 >= 4.0.6, PHP 5, PHP 7)

openssl_public_decryptРасшифровка данных с помощью открытого ключа


bool openssl_public_decrypt ( string $data , string &$decrypted , mixed $key [, int $padding = OPENSSL_PKCS1_PADDING ] )

openssl_public_decrypt() расшифровывает данные data, которые ранее были зашифрованы с помощью openssl_private_encrypt() и сохраняет результат в decrypted.

Вы можете использовать эту функцию, например, чтобы проверить, было ли сообщение написано владельцем закрытого ключа.

Список параметров




key должен содержать соответствующий открытый ключ.


padding может быть одной из констант: OPENSSL_PKCS1_PADDING, OPENSSL_NO_PADDING.

Возвращаемые значения

Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.

Смотрите также

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User Contributed Notes 3 notes

1 year ago
Just a little note on  [P.Peyremorte]'s note in manual's openssl_private_encrypt.

"- openssl_private_encrypt can encrypt a maximum of 117 chars at one time."

This depends on the length of $key:

- For a 1024 bit key length => max number of chars (bytes) to encrypt = 1024/8 - 11(when padding used) = 117 chars (bytes).
- For a 2048 bit key length => max number of chars (bytes) to encrypt = 2048/8 - 11(when padding used) = 245 chars (bytes).
... and so on

By the way, if openssl_private_encrypt fails because of data size you won't get anything but just false as returned value, the same for openssl_public_decrypt() on decryption.

"- the encrypted output string is always 129 char length. If you use base64_encode on the encrypted output, it will give always 172 chars, with the last always "=" (filler)"

This again depends on the length of $key:

- For a 1024 bit key length => encrypted number of raw bytes is always a block of 128 bytes (1024 bits) by RSA design.
- For a 2048 bit key length => encrypted number of raw bytes is always a block of 256 bytes (2048 bits) by RSA design.
... and so on

About base64_encode output length, it depends on what you encode (meaning it depends on the bytes resulting after encryption), but in general the resulting encoded string will be about a 33% bigger (for 128 bytes bout 170 bytes and for 256 bytes about 340 bytes).

I would then generalize a little [P.Peyremorte]'s note by:
// given the variables as constants:

  //Block size for encryption block cipher
private $ENCRYPT_BLOCK_SIZE = 200;// this for 2048 bit key for example, leaving some room

  //Block size for decryption block cipher
private $DECRYPT_BLOCK_SIZE = 256;// this again for 2048 bit key

         //For encryption we would use:
function encrypt_RSA($plainData, $privatePEMKey)
$encrypted = '';
$plainData = str_split($plainData, $this->ENCRYPT_BLOCK_SIZE);
$plainData as $chunk)
$partialEncrypted = '';

//using for example OPENSSL_PKCS1_PADDING as padding
$encryptionOk = openssl_private_encrypt($chunk, $partialEncrypted, $privatePEMKey, OPENSSL_PKCS1_PADDING);

$encryptionOk === false){return false;}//also you can return and error. If too big this will be false
$encrypted .= $partialEncrypted;
base64_encode($encrypted);//encoding the whole binary String as MIME base 64

//For decryption we would use:
protected function decrypt_RSA($publicPEMKey, $data)
$decrypted = '';

//decode must be done before spliting for getting the binary String
$data = str_split(base64_decode($data), $this->DECRYPT_BLOCK_SIZE);

$data as $chunk)
$partial = '';

//be sure to match padding
$decryptionOK = openssl_public_decrypt($chunk, $partial, $publicPEMKey, OPENSSL_PKCS1_PADDING);

$decryptionOK === false){return false;}//here also processed errors in decryption. If too big this will be false
$decrypted .= $partial;
wfredkNOSPAM at L5DevelopmentNOSPAM dot com
16 years ago
Encrypt using private key, decrypt using public key.

Use this for posting signed messages:  Anyone with access to
your public key can read it, but they can't create one with
your signature.

echo "Source: $source";
// $passphrase is required if your key is encoded (suggested)
$res = openssl_get_privatekey($priv_key,$passphrase);
* NOTE:  Here you use the returned resource value
"String crypted: $crypttext";

$fp=fopen ("/path/to/certificate.crt","r");
* NOTE:  Here you use the $pub_key value (converted, I guess)
"String decrypt : $newsource";
billnet at tiscalinet dot it
16 years ago
=fopen ("/path/to/certificato.pem");
$pub_key=fread ($fp,8192);
openssl_get_publickey ($pub_key);
openssl_public_decrypt ($source,$finaltext,$pub_key);
"String decrypt : $finaltext";
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