From c75608327ac9247ea1196d4b42af07f14282f7bb Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 09:50:56 +0000
Subject: [PATCH 1/6] Add legacy support for encryption and decryption methods
 in AESCryptoServiceProvider

---
 src/AESCryptoServiceProvider.php       | 26 +++++++++++++++++++-------
 tests/AESCryptoServiceProviderTest.php |  2 ++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index a009fa0..c4ef58e 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -105,7 +105,7 @@ public function generateIV(?string $cipher = null)
      * @param string $plainText
      * @return string
      */
-    public function encrypt(string $plainText): string
+    public function encrypt(string $plainText, bool $legacy = false): string
     {
         $encryptedBytes = openssl_encrypt(
             $plainText,
@@ -116,7 +116,11 @@ public function encrypt(string $plainText): string
             $this->tag
         );
 
-        return base64_encode($this->iv . $this->tag . $encryptedBytes);
+        if ($legacy) {
+            return base64_encode($this->iv . $this->tag . $encryptedBytes);
+        }
+
+        return base64_encode($this->iv . $encryptedBytes . $this->tag);
     }
 
     /**
@@ -127,7 +131,7 @@ public function encrypt(string $plainText): string
      * @throws DecryptException
      * @throws IvGenerateException
      */
-    public function decrypt(string $encryptedData): string
+    public function decrypt(string $encryptedData, bool $legacy = false): string
     {
         $c = base64_decode($encryptedData);
 
@@ -137,10 +141,18 @@ public function decrypt(string $encryptedData): string
             throw new IvGenerateException();
         }
 
-        $this->iv = substr($c, 0, $iv_len);
-        $this->tag = substr($c, $iv_len, static::DEFAULT_GCM_TAG_LENGTH);
-        $encryptedBytes = substr($c, $iv_len + static::DEFAULT_GCM_TAG_LENGTH);
-
+        if ($legacy) {
+            // IV-TAG-EncryptedData
+            $this->iv = substr($c, 0, $iv_len); // from begining to iv lenght 12 bytes
+            $this->tag = substr($c, $iv_len, static::DEFAULT_GCM_TAG_LENGTH); // tag is 16 bytes after iv
+            $encryptedBytes = substr($c, $iv_len + static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are at the end
+        } else {
+            // IV-EncryptedData-TAG
+            $this->iv = substr($c, 0, $iv_len); // from begining to iv lenght 12 bytes
+            $encryptedBytes = substr($c, $iv_len, -static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are in the middle
+            $this->tag = substr($c, -static::DEFAULT_GCM_TAG_LENGTH); // tag is at the end
+        }
+        
         $decryptedText =  openssl_decrypt(
             $encryptedBytes,
             $this->cipher,
diff --git a/tests/AESCryptoServiceProviderTest.php b/tests/AESCryptoServiceProviderTest.php
index e53535d..0d7f609 100644
--- a/tests/AESCryptoServiceProviderTest.php
+++ b/tests/AESCryptoServiceProviderTest.php
@@ -16,10 +16,12 @@ public function textCanBeEncryptedAndDecrypted() : void
 
         $plainText = "This is going to be encrypted!";
         $encryptedText= $csp->encrypt($plainText);
+        $encryptedTextLegacy = $csp->encrypt($plainText, legacy: true);
 
         $csp2 = new AESCryptoServiceProvider();
         $csp2->setKey($key);
 
         $this->assertEquals($plainText, $csp2->decrypt($encryptedText));
+        $this->assertEquals($plainText, $csp2->decrypt($encryptedTextLegacy, legacy: true));
     }
 }
\ No newline at end of file

From f75e0ff8f556b85a7c8b4b15a47b66348e1edb6c Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 09:53:51 +0000
Subject: [PATCH 2/6] Fix CS Errors

---
 src/AESCryptoServiceProvider.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index c4ef58e..224f51c 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -152,7 +152,7 @@ public function decrypt(string $encryptedData, bool $legacy = false): string
             $encryptedBytes = substr($c, $iv_len, -static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are in the middle
             $this->tag = substr($c, -static::DEFAULT_GCM_TAG_LENGTH); // tag is at the end
         }
-        
+
         $decryptedText =  openssl_decrypt(
             $encryptedBytes,
             $this->cipher,

From a6ef622a7bdfef84d62c5d0987efaf1b73c33dd6 Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 09:55:23 +0000
Subject: [PATCH 3/6] Enhance documentation for encrypt and decrypt methods to
 clarify legacy parameter usage

---
 src/AESCryptoServiceProvider.php | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index 224f51c..6b39e0f 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -103,6 +103,9 @@ public function generateIV(?string $cipher = null)
      * Returns encrypted text
      *
      * @param string $plainText
+     * @param bool $legacy
+     * If true, returns IV-TAG-EncryptedData format
+     * If false, returns IV-EncryptedData-TAG format
      * @return string
      */
     public function encrypt(string $plainText, bool $legacy = false): string
@@ -127,6 +130,9 @@ public function encrypt(string $plainText, bool $legacy = false): string
      * Decrypt given text
      *
      * @param string $encryptedData
+     * @param bool $legacy
+     * If true, expects IV-TAG-EncryptedData format
+     * If false, expects IV-EncryptedData-TAG format
      * @return string
      * @throws DecryptException
      * @throws IvGenerateException

From 8c58d37a517c0cbf274b3aa6c09e4dc6e9e23f40 Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 10:00:43 +0000
Subject: [PATCH 4/6] Refactor IV and TAG handling in decrypt method for
 clarity and consistency

---
 src/AESCryptoServiceProvider.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index 6b39e0f..fb55044 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -147,14 +147,14 @@ public function decrypt(string $encryptedData, bool $legacy = false): string
             throw new IvGenerateException();
         }
 
+        $this->iv = substr($c, 0, $iv_len);
+
         if ($legacy) {
             // IV-TAG-EncryptedData
-            $this->iv = substr($c, 0, $iv_len); // from begining to iv lenght 12 bytes
             $this->tag = substr($c, $iv_len, static::DEFAULT_GCM_TAG_LENGTH); // tag is 16 bytes after iv
             $encryptedBytes = substr($c, $iv_len + static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are at the end
         } else {
             // IV-EncryptedData-TAG
-            $this->iv = substr($c, 0, $iv_len); // from begining to iv lenght 12 bytes
             $encryptedBytes = substr($c, $iv_len, -static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are in the middle
             $this->tag = substr($c, -static::DEFAULT_GCM_TAG_LENGTH); // tag is at the end
         }

From e2d4af68c56db7ef1f030f27ec2b61c809bf087c Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 10:49:11 +0000
Subject: [PATCH 5/6] Refactor encrypt method to use buildPayload for
 consistent data formatting

---
 src/AESCryptoServiceProvider.php | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index fb55044..e06eb9b 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -119,11 +119,30 @@ public function encrypt(string $plainText, bool $legacy = false): string
             $this->tag
         );
 
-        if ($legacy) {
-            return base64_encode($this->iv . $this->tag . $encryptedBytes);
-        }
+        return base64_encode($this->buildPayload(
+            iv: $this->iv,
+            tag: $this->tag,
+            encryptedData: $encryptedBytes,
+            legacy: $legacy
+        ));
+    }
 
-        return base64_encode($this->iv . $encryptedBytes . $this->tag);
+    /**
+     * Build payload for encrypted data
+     *
+     * @param string $iv
+     * @param string $tag
+     * @param string $encryptedData
+     * @param bool $legacy
+     * If true, returns IV-TAG-EncryptedData format
+     * If false, returns IV-EncryptedData-TAG format
+     * @return string
+     */
+    protected function buildPayload(string $iv, string $tag, string $encryptedData, bool $legacy): string
+    {
+        return $legacy
+            ? $iv . $tag . $encryptedData // IV-TAG-EncryptedData
+            : $iv . $encryptedData . $tag; // IV-EncryptedData-TAG
     }
 
     /**

From f7cacde0d95da308cb879962a9ba3b93f4b48615 Mon Sep 17 00:00:00 2001
From: May Meow <3164256+MayMeow@users.noreply.github.com>
Date: Wed, 4 Jun 2025 11:07:43 +0000
Subject: [PATCH 6/6] Refactor decrypt method to use parsePayload for improved
 clarity and maintainability

---
 src/AESCryptoServiceProvider.php | 36 ++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/src/AESCryptoServiceProvider.php b/src/AESCryptoServiceProvider.php
index e06eb9b..0c44a56 100644
--- a/src/AESCryptoServiceProvider.php
+++ b/src/AESCryptoServiceProvider.php
@@ -166,17 +166,11 @@ public function decrypt(string $encryptedData, bool $legacy = false): string
             throw new IvGenerateException();
         }
 
-        $this->iv = substr($c, 0, $iv_len);
-
-        if ($legacy) {
-            // IV-TAG-EncryptedData
-            $this->tag = substr($c, $iv_len, static::DEFAULT_GCM_TAG_LENGTH); // tag is 16 bytes after iv
-            $encryptedBytes = substr($c, $iv_len + static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are at the end
-        } else {
-            // IV-EncryptedData-TAG
-            $encryptedBytes = substr($c, $iv_len, -static::DEFAULT_GCM_TAG_LENGTH); // encrypted data are in the middle
-            $this->tag = substr($c, -static::DEFAULT_GCM_TAG_LENGTH); // tag is at the end
-        }
+        [$this->iv, $encryptedBytes, $this->tag] = $this->parsePayload(
+            cipherText: $c,
+            ivLength: $iv_len,
+            legacy: $legacy
+        );
 
         $decryptedText =  openssl_decrypt(
             $encryptedBytes,
@@ -194,6 +188,26 @@ public function decrypt(string $encryptedData, bool $legacy = false): string
         return  $decryptedText;
     }
 
+    /**
+     * Parse payload from encrypted data
+     *
+     * @param string $cipherText
+     * @param int $ivLength
+     * @param bool $legacy
+     * If true, expects IV-TAG-EncryptedData format
+     * If false, expects IV-EncryptedData-TAG format
+     * @return array That contains IV, EncryptedData and TAG in that order
+     */
+    protected function parsePayload(string $cipherText, int $ivLength, bool $legacy = false): array
+    {
+        $iv = substr($cipherText, 0, $ivLength);
+        $tagLength = static::DEFAULT_GCM_TAG_LENGTH;
+
+        return $legacy
+            ? [$iv, substr($cipherText, $ivLength + $tagLength), substr($cipherText, $ivLength, $tagLength)]
+            : [$iv, substr($cipherText, $ivLength, -$tagLength), substr($cipherText, -$tagLength)];
+    }
+
     /**
      * Seal data using AES-256-CBC and public key
      *