openssl_public_decrypt()
(PHP 4 >= 4.0.6, PHP 5, PHP 7)
使用公钥解密数据
说明
openssl_public_decrypt(string $data,string &$decrypted, mixed $key[,int $padding= OPENSSL_PKCS1_PADDING]): bool
openssl_public_decrypt()解密先前由openssl_private_encrypt()加密的数据$data并且将结果保存至变量$decrypted中。
你可以用该函数来校验消息是否是私钥拥有者写的。
参数
- $data
- $decrypted
- $key
$key必须是和用来加密数据的私钥配对的公钥。
- $padding
$padding可以是如下至
OPENSSL_PKCS1_PADDING
,OPENSSL_NO_PADDING
.
返回值
成功时返回TRUE
,或者在失败时返回FALSE
。
参见
openssl_private_encrypt()
使用私钥加密数据openssl_private_decrypt()
使用私钥解密数据
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: <?php // 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, $this->ENCRYPT_BLOCK_SIZE); foreach($plainData as $chunk) { $partialEncrypted = ''; //using for example OPENSSL_PKCS1_PADDING as padding $encryptionOk = openssl_private_encrypt($chunk, $partialEncrypted, $privatePEMKey, OPENSSL_PKCS1_PADDING); if($encryptionOk === false){return false;}//also you can return and error. If too big this will be false $encrypted .= $partialEncrypted; } return base64_encode($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), $this->DECRYPT_BLOCK_SIZE); foreach($data as $chunk) { $partial = ''; //be sure to match padding $decryptionOK = openssl_public_decrypt($chunk, $partial, $publicPEMKey, OPENSSL_PKCS1_PADDING); if($decryptionOK === false){return false;}//here also processed errors in decryption. If too big this will be false $decrypted .= $partial; } return $decrypted; } ?>
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. <?php echo "Source: $source"; $fp=fopen("/path/to/private.key","r"); $priv_key=fread($fp,8192); fclose($fp); // $passphrase is required if your key is encoded (suggested) $res = openssl_get_privatekey($priv_key,$passphrase); /* * NOTE: Here you use the returned resource value */ openssl_private_encrypt($source,$crypttext,$res); echo "String crypted: $crypttext"; $fp=fopen ("/path/to/certificate.crt","r"); $pub_key=fread($fp,8192); fclose($fp); openssl_get_publickey($pub_key); /* * NOTE: Here you use the $pub_key value (converted, I guess) */ openssl_public_decrypt($crypttext,$newsource,$pub_key); echo "String decrypt : $newsource"; ?>
<?php $fp=fopen ("/path/to/certificato.pem"); $pub_key=fread ($fp,8192); openssl_get_publickey ($pub_key); openssl_public_decrypt ($source,$finaltext,$pub_key); echo "String decrypt : $finaltext"; ?>