$ pri _ key =

$ pub _ key =

$char =' square box'; //Characters to be encrypted

$ sign = $ this-& gt； RsaEncrypt($char，$ pri _ key)； //Encrypt the result

$ result = $ this-& gt； RsaDecrypt($sign，$ pub _ key)； //Decrypt the encrypted result.

Encryption:

Common function RsaEncrypt($str, $ pri _ key) (

$ pi _ key = OpenSSL _ pkey _ get _ private($ pri _ key)；

If (! $pi_key) returns false// The key is not available.

openssl_private_encrypt($str，$encrypted，$ pi _ key)；

$ encrypted = base64 _ encode($ encrypted)；

Return $ encrypted

}

Decryption:

Public function RsaDecrypt($str, $pub_key){

$ pu _ key = OpenSSL _ pkey _ get _ public($ pub _ key)；

If (! $pu_key) returns false// The key is not available.

OpenSSL _ public _ decrypt(base64 _ decode($ str)，$decrypted，$ pu _ key)；

Return to $ decrypted

}

Note: Open the php _ OpenSSL extension of PHP.