diff --git a/ext/openssl/ossl_cipher.c b/ext/openssl/ossl_cipher.c
index 2685151..7119285 100644
--- a/ext/openssl/ossl_cipher.c
+++ b/ext/openssl/ossl_cipher.c
@@ -403,6 +403,35 @@ ossl_cipher_final(VALUE self)
 
 /*
  *  call-seq:
+ *     cipher.verify -> string
+ *
+ *  Verifies the decrypted ciphertext against the tag set prior to
+ *  decryption using the ciphertext and optional associated
+ *  authentication data. Returns an empty string if the ciphertext was
+ *  authenticated successfully, otherwise raises an
+ *  OpenSSL::Cipher::CipherError.
+ *
+ *  Only call this method after setting the authentication tag
+ *  appropriate for your cipher mode and passing the entire contents
+ *  of the ciphertext into the cipher, and before calling
+ *  Cipher#final.
+ */
+static VALUE
+ossl_cipher_verify(VALUE self)
+{
+    EVP_CIPHER_CTX *ctx;
+    int             out_len = 0;
+
+    GetCipher(self, ctx);
+
+    if (!EVP_CipherUpdate(ctx, NULL, &out_len, NULL, 0))
+        ossl_raise(eCipherError, "ciphertext failed to authenticate");
+
+    return rb_str_new(0, 0);
+}
+
+/*
+ *  call-seq:
  *     cipher.name -> string
  *
  *  Returns the name of the cipher which may differ slightly from the original
@@ -478,6 +507,97 @@ ossl_cipher_set_iv(VALUE self, VALUE iv)
     return iv;
 }
 
+/*
+ *  call-seq:
+ *     cipher.aad = string -> string
+ *
+ *  Sets the cipher's additional authenticated data. This field may be
+ *  set optionally before using AEAD cipher modes such as GCM or
+ *  CCM. The contents of this field should be non-sensitive
+ *  data which will be added to the ciphertext to generate the
+ *  authentication tag which validates the contents of the ciphertext.
+ *
+ *  The AAD must be set prior to encryption or decryption. Only call
+ *  this method after calling Cipher#encrypt when encrypting, and
+ *  after Cipher#decrypt and Cipher#gcm_tag= when decrypting.
+ */
+static VALUE
+ossl_cipher_set_aad(VALUE self, VALUE data)
+{
+    EVP_CIPHER_CTX *ctx;
+    unsigned char  *in      = NULL;
+    int             in_len  = 0;
+    int             out_len = 0;
+
+    StringValue(data);
+
+    in     = (unsigned char *) RSTRING_PTR(data);
+    in_len = RSTRING_LENINT(data);
+
+    GetCipher(self, ctx);
+
+    if (!EVP_CipherUpdate(ctx, NULL, &out_len, in, in_len))
+        ossl_raise(eCipherError, "couldn't set additional authenticated data");
+
+    return self;
+}
+
+/*
+ *  call-seq:
+ *     cipher.gcm_tag -> string
+ *
+ *  Gets the authentication tag generated by GCM cipher modes. This
+ *  tag may be stored along with the ciphertext, then set on the
+ *  decryption cipher to authenticate the contents of the ciphertext
+ *  against changes.
+ *
+ *  The tag may only be retrieved after calling Cipher#final.
+ */
+static VALUE
+ossl_cipher_get_gcm_tag(VALUE self)
+{
+    EVP_CIPHER_CTX *ctx;
+    VALUE           tag;
+
+    // GCM tags are 16 bytes in OpenSSL
+    tag = rb_str_new(NULL, 16);
+
+    GetCipher(self, ctx);
+
+    if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, (unsigned char *)RSTRING_PTR(tag)))
+        ossl_raise(eCipherError, "Cipher#finish must be called before getting the tag");
+
+    return tag;
+}
+
+/*
+ *  call-seq:
+ *     cipher.gcm_tag = string -> string
+ *
+ *  Sets the authentication tag to verify the contents of the
+ *  ciphertext. The GCM tag must be set after calling Cipher#decrypt
+ *  but before decrypting any of the ciphertext. After all decryption
+ *  is performed, the tag can be verified by calling Cipher#verify.
+ */
+static VALUE
+ossl_cipher_set_gcm_tag(VALUE self, VALUE data)
+{
+    EVP_CIPHER_CTX *ctx;
+    unsigned char  *in     = NULL;
+    int             in_len = 0;
+
+    StringValue(data);
+
+    in     = (unsigned char *) RSTRING_PTR(data);
+    in_len = RSTRING_LENINT(data);
+
+    GetCipher(self, ctx);
+
+    if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, in_len, in))
+        ossl_raise(eCipherError, "unable to set GCM tag");
+
+    return data;
+}
 
 /*
  *  call-seq:
@@ -742,8 +862,12 @@ Init_ossl_cipher(void)
     rb_define_method(cCipher, "pkcs5_keyivgen", ossl_cipher_pkcs5_keyivgen, -1);
     rb_define_method(cCipher, "update", ossl_cipher_update, -1);
     rb_define_method(cCipher, "final", ossl_cipher_final, 0);
+    rb_define_method(cCipher, "verify", ossl_cipher_verify, 0);
     rb_define_method(cCipher, "name", ossl_cipher_name, 0);
     rb_define_method(cCipher, "key=", ossl_cipher_set_key, 1);
+    rb_define_method(cCipher, "aad=", ossl_cipher_set_aad, 1);
+    rb_define_method(cCipher, "gcm_tag=", ossl_cipher_set_gcm_tag, 1);
+    rb_define_method(cCipher, "gcm_tag", ossl_cipher_get_gcm_tag, 0);
     rb_define_method(cCipher, "key_len=", ossl_cipher_set_key_length, 1);
     rb_define_method(cCipher, "key_len", ossl_cipher_key_length, 0);
     rb_define_method(cCipher, "iv=", ossl_cipher_set_iv, 1);
diff --git a/test/openssl/test_cipher.rb b/test/openssl/test_cipher.rb
index 0e4a775..8620be3 100644
--- a/test/openssl/test_cipher.rb
+++ b/test/openssl/test_cipher.rb
@@ -101,6 +101,38 @@ class OpenSSL::TestCipher < Test::Unit::TestCase
       end
     end
   end
+
+  if OpenSSL::OPENSSL_VERSION_NUMBER > 0x1000103f
+    def test_aes_gcm
+      pt = File.read(__FILE__)
+      c1 = OpenSSL::Cipher.new('aes-256-gcm')
+      c2 = OpenSSL::Cipher.new('aes-256-gcm')
+      c3 = OpenSSL::Cipher.new('aes-256-gcm')
+
+      c1.encrypt
+      c1.pkcs5_keyivgen('passwd')
+      c1.aad = 'aad'
+
+      ct  = c1.update(pt) + c1.final
+      tag = c1.gcm_tag
+
+      c2.decrypt
+      c2.pkcs5_keyivgen('passwd')
+      c2.gcm_tag = tag
+      c2.aad     = 'aad'
+
+      assert_equal(pt, c2.update(ct) + c2.verify + c2.final)
+
+      c3.decrypt
+      c3.pkcs5_keyivgen('passwd')
+      c3.gcm_tag = tag[0..-2] << tag[-1].succ
+      c3.aad     = 'aad'
+
+      assert_raise OpenSSL::Cipher::CipherError do
+        c3.update(ct) + c3.verify + c3.final
+      end
+    end
+  end
 end
 
 end