RSA: split ciphertext and plaintext up by block size

phpseclib · Dec 29, 2020 · 8d540e1 · 8d540e1
1 parent 9a4cfa4
commit 8d540e1
Showing 1 changed file with 31 additions and 3 deletions.
diff --git a/src/Crypt/RSA.php b/src/Crypt/RSA.php
@@ -456,7 +456,7 @@ public function __toString()
      */
     public function setPublicKey()
     {
-        return false;        
+        return false;
     }
 
     /**
@@ -823,7 +823,23 @@ public function getComment()
     public function encrypt($plaintext)
     {
         if ($this->key instanceof PublicKey) {
-            return $this->key->encrypt($plaintext);
+            switch ($this->encryptionMode) {
+                case self::ENCRYPTION_PKCS1:
+                    $len = ($this->key->getLength() - 88) >> 3;
+                    break;
+                case self::ENCRYPTION_NONE:
+                    $len = $this->key->getLength() >> 3;
+                    break;
+                //case self::ENCRYPTION_OAEP:
+                default:
+                    $len = ($this->key->getLength() - 2 * $this->key->getHash()->getLength() - 16) >> 3;
+            }
+            $plaintext = str_split($plaintext, $len);
+            $ciphertext = '';
+            foreach ($plaintext as $m) {
+                $ciphertext.= $this->key->encrypt($m);
+            }
+            return $ciphertext;
         }
 
         return false;
@@ -840,7 +856,19 @@ public function encrypt($plaintext)
     public function decrypt($ciphertext)
     {
         if ($this->key instanceof PrivateKey) {
-            return $this->key->decrypt($ciphertext);
+            $len = $this->key->getLength() >> 3;
+            $ciphertext = str_split($ciphertext, $len);
+            $ciphertext[count($ciphertext) - 1] = str_pad($ciphertext[count($ciphertext) - 1], $len, chr(0), STR_PAD_LEFT);
+
+            $plaintext = '';
+            foreach ($ciphertext as $c) {
+                try {
+                    $plaintext.= $this->key->decrypt($c);
+                } catch (\Exception $e) {
+                    return false;
+                }
+            }
+            return $plaintext;
         }
 
         return false;