diff --git a/src/Illuminate/Encryption/Encrypter.php b/src/Illuminate/Encryption/Encrypter.php
index a4351c99285d..5c9db55e5db1 100755
--- a/src/Illuminate/Encryption/Encrypter.php
+++ b/src/Illuminate/Encryption/Encrypter.php
@@ -30,10 +30,10 @@ class Encrypter implements EncrypterContract, StringEncrypter
      * @var array
      */
     private static $supportedCiphers = [
-        'AES-128-CBC' => ['size' => 16, 'aead' => false],
-        'AES-256-CBC' => ['size' => 32, 'aead' => false],
-        'AES-128-GCM' => ['size' => 16, 'aead' => true],
-        'AES-256-GCM' => ['size' => 32, 'aead' => true],
+        'aes-128-cbc' => ['size' => 16, 'aead' => false],
+        'aes-256-cbc' => ['size' => 32, 'aead' => false],
+        'aes-128-gcm' => ['size' => 16, 'aead' => true],
+        'aes-256-gcm' => ['size' => 32, 'aead' => true],
     ];
 
     /**
@@ -45,11 +45,11 @@ class Encrypter implements EncrypterContract, StringEncrypter
      *
      * @throws \RuntimeException
      */
-    public function __construct($key, $cipher = 'AES-128-CBC')
+    public function __construct($key, $cipher = 'aes-128-cbc')
     {
         $key = (string) $key;
 
-        if (! static::supported($key, $cipher)) {
+        if (! static::supported($key, strtolower($cipher))) {
             $ciphers = implode(', ', array_keys(self::$supportedCiphers));
 
             throw new RuntimeException("Unsupported cipher or incorrect key length. Supported ciphers are: {$ciphers}.");
@@ -83,7 +83,7 @@ public static function supported($key, $cipher)
      */
     public static function generateKey($cipher)
     {
-        return random_bytes(self::$supportedCiphers[$cipher]['size'] ?? 32);
+        return random_bytes(self::$supportedCiphers[strtolower($cipher)]['size'] ?? 32);
     }
 
     /**
@@ -97,18 +97,18 @@ public static function generateKey($cipher)
      */
     public function encrypt($value, $serialize = true)
     {
-        $iv = random_bytes(openssl_cipher_iv_length($this->cipher));
+        $iv = random_bytes(openssl_cipher_iv_length(strtolower($this->cipher)));
 
         $tag = '';
 
-        $value = self::$supportedCiphers[$this->cipher]['aead']
+        $value = self::$supportedCiphers[strtolower($this->cipher)]['aead']
             ? \openssl_encrypt(
                 $serialize ? serialize($value) : $value,
-                $this->cipher, $this->key, 0, $iv, $tag
+                strtolower($this->cipher), $this->key, 0, $iv, $tag
             )
             : \openssl_encrypt(
                 $serialize ? serialize($value) : $value,
-                $this->cipher, $this->key, 0, $iv
+                strtolower($this->cipher), $this->key, 0, $iv
             );
 
         if ($value === false) {
@@ -118,7 +118,7 @@ public function encrypt($value, $serialize = true)
         $iv = base64_encode($iv);
         $tag = base64_encode($tag);
 
-        $mac = self::$supportedCiphers[$this->cipher]['aead']
+        $mac = self::$supportedCiphers[strtolower($this->cipher)]['aead']
             ? '' // For AEAD-algoritms, the tag / MAC is returned by openssl_encrypt...
             : $this->hash($iv, $value);
 
@@ -165,7 +165,7 @@ public function decrypt($payload, $unserialize = true)
         // we will then unserialize it and return it out to the caller. If we are
         // unable to decrypt this value we will throw out an exception message.
         $decrypted = \openssl_decrypt(
-            $payload['value'], $this->cipher, $this->key, 0, $iv, $tag
+            $payload['value'], strtolower($this->cipher), $this->key, 0, $iv, $tag
         );
 
         if ($decrypted === false) {
@@ -219,7 +219,7 @@ protected function getJsonPayload($payload)
             throw new DecryptException('The payload is invalid.');
         }
 
-        if (! self::$supportedCiphers[$this->cipher]['aead'] && ! $this->validMac($payload)) {
+        if (! self::$supportedCiphers[strtolower($this->cipher)]['aead'] && ! $this->validMac($payload)) {
             throw new DecryptException('The MAC is invalid.');
         }
 
@@ -235,7 +235,7 @@ protected function getJsonPayload($payload)
     protected function validPayload($payload)
     {
         return is_array($payload) && isset($payload['iv'], $payload['value'], $payload['mac']) &&
-            strlen(base64_decode($payload['iv'], true)) === openssl_cipher_iv_length($this->cipher);
+            strlen(base64_decode($payload['iv'], true)) === openssl_cipher_iv_length(strtolower($this->cipher));
     }
 
     /**
diff --git a/tests/Encryption/EncrypterTest.php b/tests/Encryption/EncrypterTest.php
index 8db4a0299175..fc3ab90e4879 100755
--- a/tests/Encryption/EncrypterTest.php
+++ b/tests/Encryption/EncrypterTest.php
@@ -56,6 +56,19 @@ public function testWithCustomCipher()
         $this->assertSame('foo', $e->decrypt($encrypted));
     }
 
+    public function testCipherNamesCanBeMixedCase()
+    {
+        $upper = new Encrypter(str_repeat('b', 16), 'AES-128-GCM');
+        $encrypted = $upper->encrypt('bar');
+        $this->assertNotSame('bar', $encrypted);
+
+        $lower = new Encrypter(str_repeat('b', 16), 'aes-128-gcm');
+        $this->assertSame('bar', $lower->decrypt($encrypted));
+
+        $mixed = new Encrypter(str_repeat('b', 16), 'aEs-128-GcM');
+        $this->assertSame('bar', $mixed->decrypt($encrypted));
+    }
+
     public function testThatAnAeadCipherIncludesTag()
     {
         $e = new Encrypter(str_repeat('b', 32), 'AES-256-GCM');
@@ -79,7 +92,7 @@ public function testThatANonAeadCipherIncludesMac()
     public function testDoNoAllowLongerKey()
     {
         $this->expectException(RuntimeException::class);
-        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: AES-128-CBC, AES-256-CBC, AES-128-GCM, AES-256-GCM.');
+        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: aes-128-cbc, aes-256-cbc, aes-128-gcm, aes-256-gcm.');
 
         new Encrypter(str_repeat('z', 32));
     }
@@ -87,7 +100,7 @@ public function testDoNoAllowLongerKey()
     public function testWithBadKeyLength()
     {
         $this->expectException(RuntimeException::class);
-        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: AES-128-CBC, AES-256-CBC, AES-128-GCM, AES-256-GCM.');
+        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: aes-128-cbc, aes-256-cbc, aes-128-gcm, aes-256-gcm.');
 
         new Encrypter(str_repeat('a', 5));
     }
@@ -95,15 +108,15 @@ public function testWithBadKeyLength()
     public function testWithBadKeyLengthAlternativeCipher()
     {
         $this->expectException(RuntimeException::class);
-        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: AES-128-CBC, AES-256-CBC, AES-128-GCM, AES-256-GCM.');
+        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: aes-128-cbc, aes-256-cbc, aes-128-gcm, aes-256-gcm.');
 
-        new Encrypter(str_repeat('a', 16), 'AES-256-CFB8');
+        new Encrypter(str_repeat('a', 16), 'AES-256-GCM');
     }
 
     public function testWithUnsupportedCipher()
     {
         $this->expectException(RuntimeException::class);
-        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: AES-128-CBC, AES-256-CBC, AES-128-GCM, AES-256-GCM.');
+        $this->expectExceptionMessage('Unsupported cipher or incorrect key length. Supported ciphers are: aes-128-cbc, aes-256-cbc, aes-128-gcm, aes-256-gcm.');
 
         new Encrypter(str_repeat('c', 16), 'AES-256-CFB8');
     }