From bfb49c06e8a2447827563807d670c565fc01ce9a Mon Sep 17 00:00:00 2001
From: terrafrost <terrafrost@gmail.com>
Date: Tue, 5 Jan 2021 08:04:40 -0600
Subject: [PATCH] RSA: throw exceptions instead of returning false

---
 phpseclib/Crypt/RSA.php            |  2 +-
 phpseclib/Crypt/RSA/PrivateKey.php | 26 ++++++++++----------------
 phpseclib/Crypt/RSA/PublicKey.php  |  5 ++++-
 3 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 762e0269..90e4e8df 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -481,7 +481,7 @@ abstract class RSA extends AsymmetricKey
         }
         $x = $x->toBytes();
         if (strlen($x) > $xLen) {
-            return false;
+            throw new \OutOfRangeException('Resultant string length out of range');
         }
         return str_pad($x, $xLen, chr(0), STR_PAD_LEFT);
     }
diff --git a/phpseclib/Crypt/RSA/PrivateKey.php b/phpseclib/Crypt/RSA/PrivateKey.php
index c1c73fa8..2830d982 100644
--- a/phpseclib/Crypt/RSA/PrivateKey.php
+++ b/phpseclib/Crypt/RSA/PrivateKey.php
@@ -79,7 +79,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
     private function rsadp($c)
     {
         if ($c->compare(self::$zero) < 0 || $c->compare($this->modulus) > 0) {
-            return false;
+            throw new \OutOfRangeException('Ciphertext representative out of range');
         }
         return $this->exponentiate($c);
     }
@@ -96,7 +96,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
     private function rsasp1($m)
     {
         if ($m->compare(self::$zero) < 0 || $m->compare($this->modulus) > 0) {
-            return false;
+            throw new \OutOfRangeException('Signature representative out of range');
         }
         return $this->exponentiate($m);
     }
@@ -224,7 +224,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
 
         $mHash = $this->hash->hash($m);
         if ($emLen < $this->hLen + $sLen + 2) {
-            return false;
+            throw new \LengthException('RSA modulus too short');
         }
 
         $salt = Random::string($sLen);
@@ -333,7 +333,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
         // Length checking
 
         if (strlen($c) != $this->k) { // or if k < 11
-            return false;
+            throw new \LengthException('Ciphertext representative too long');
         }
 
         // RSA decryption
@@ -341,21 +341,18 @@ class PrivateKey extends RSA implements Common\PrivateKey
         $c = $this->os2ip($c);
         $m = $this->rsadp($c);
         $em = $this->i2osp($m, $this->k);
-        if ($em === false) {
-            return false;
-        }
 
         // EME-PKCS1-v1_5 decoding
 
         if (ord($em[0]) != 0 || ord($em[1]) > 2) {
-            return false;
+            throw new \RuntimeException('Decryption error');
         }
 
         $ps = substr($em, 2, strpos($em, chr(0), 2) - 2);
         $m = substr($em, strlen($ps) + 3);
 
         if (strlen($ps) < 8) {
-            return false;
+            throw new \RuntimeException('Decryption error');
         }
 
         // Output M
@@ -389,7 +386,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
         // be output.
 
         if (strlen($c) != $this->k || $this->k < 2 * $this->hLen + 2) {
-            return false;
+            throw new \LengthException('Ciphertext representative too long');
         }
 
         // RSA decryption
@@ -397,9 +394,6 @@ class PrivateKey extends RSA implements Common\PrivateKey
         $c = $this->os2ip($c);
         $m = $this->rsadp($c);
         $em = $this->i2osp($m, $this->k);
-        if ($em === false) {
-            return false;
-        }
 
         // EME-OAEP decoding
 
@@ -426,7 +420,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
         // we do & instead of && to avoid https://en.wikipedia.org/wiki/Short-circuit_evaluation
         // to protect against timing attacks
         if (!$hashesMatch & !$patternMatch) {
-            return false;
+            throw new \RuntimeException('Decryption error');
         }
 
         // Output the message M
@@ -447,7 +441,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
     private function raw_encrypt($m)
     {
         if (strlen($m) > $this->k) {
-            throw new \LengthException('Message too long');
+            throw new \LengthException('Ciphertext representative too long');
         }
 
         $temp = $this->os2ip($m);
@@ -486,7 +480,7 @@ class PrivateKey extends RSA implements Common\PrivateKey
     {
         $type = self::validatePlugin('Keys', 'PKCS8', 'savePublicKey');
         if (empty($this->modulus) || empty($this->publicExponent)) {
-            return false;
+            throw new \RuntimeException('Public key components not found');
         }
 
         $key = $type::savePublicKey($this->modulus, $this->publicExponent);
diff --git a/phpseclib/Crypt/RSA/PublicKey.php b/phpseclib/Crypt/RSA/PublicKey.php
index c78be17b..4a080d7c 100644
--- a/phpseclib/Crypt/RSA/PublicKey.php
+++ b/phpseclib/Crypt/RSA/PublicKey.php
@@ -87,6 +87,9 @@ class PublicKey extends RSA implements Common\PublicKey
 
         $s = $this->os2ip($s);
         $m2 = $this->rsavp1($s);
+        if ($m2 === false) {
+            return false;
+        }
         $em = $this->i2osp($m2, $this->k);
         if ($em === false) {
             return false;
@@ -400,7 +403,7 @@ class PublicKey extends RSA implements Common\PublicKey
     private function rsaep($m)
     {
         if ($m->compare(self::$zero) < 0 || $m->compare($this->modulus) > 0) {
-            return false;
+            throw new \OutOfRangeException('Message representative out of range');
         }
         return $this->exponentiate($m);
     }