asymmetriccipher.php

См. документацию.

<?php
namespace Bitrix\Main\Security;
 
abstract class AsymmetricCipher
{
    public function encrypt($data, $key): bool|string
    {
        $keyInfo  = $this->getKeyInfo($key);
        $chunkSize = $keyInfo['bits']/8 - 11;
 
        $result = '';
 
        foreach (str_split($data, $chunkSize) as $chunk)
        {
            $encryptedChunk = $this->doEncrypt($chunk, $key);
 
            if ($encryptedChunk === false)
            {
                return false;
            }
 
            $result .= $encryptedChunk;
        }
 
        return base64_encode($result);
    }

    public function decrypt($data, $key): bool|string
    {
        $result = '';
 
        $keyInfo  = $this->getKeyInfo($key);
        $blockSize = $keyInfo['bits']/8;
 
        foreach(str_split(base64_decode($data), $blockSize) as $chunk)
        {
            $decryptedChunk = $this->doDecrypt($chunk, $key);
 
            if ($decryptedChunk === false)
            {
                return false;
            }
 
            $result .= $decryptedChunk;
        }
 
        return $result;
    }

    abstract protected function doEncrypt($data, $key);

    abstract protected function doDecrypt($data, $key);

    abstract protected function getKeyInfo($key);
}