diff --git a/crypto/err/openssl.txt b/crypto/err/openssl.txt
index bf440f33b6b7b40dd5b0b74f5d6a9d3b7325b5c3..bb6b932fe026bb2d9e3937ff331dda69908bd698 100644
--- a/crypto/err/openssl.txt
+++ b/crypto/err/openssl.txt
@@ -714,11 +714,14 @@ ENGINE_F_INT_ENGINE_CONFIGURE:188:int_engine_configure
 ENGINE_F_INT_ENGINE_MODULE_INIT:187:int_engine_module_init
 ENGINE_F_OSSL_HMAC_INIT:200:ossl_hmac_init
 EVP_F_AESNI_INIT_KEY:165:aesni_init_key
+EVP_F_AESNI_XTS_INIT_KEY:207:aesni_xts_init_key
 EVP_F_AES_GCM_CTRL:196:aes_gcm_ctrl
 EVP_F_AES_INIT_KEY:133:aes_init_key
 EVP_F_AES_OCB_CIPHER:169:aes_ocb_cipher
 EVP_F_AES_T4_INIT_KEY:178:aes_t4_init_key
+EVP_F_AES_T4_XTS_INIT_KEY:208:aes_t4_xts_init_key
 EVP_F_AES_WRAP_CIPHER:170:aes_wrap_cipher
+EVP_F_AES_XTS_INIT_KEY:209:aes_xts_init_key
 EVP_F_ALG_MODULE_INIT:177:alg_module_init
 EVP_F_ARIA_CCM_INIT_KEY:175:aria_ccm_init_key
 EVP_F_ARIA_GCM_CTRL:197:aria_gcm_ctrl
@@ -2289,6 +2292,7 @@ EVP_R_UNSUPPORTED_PRIVATE_KEY_ALGORITHM:118:unsupported private key algorithm
 EVP_R_UNSUPPORTED_SALT_TYPE:126:unsupported salt type
 EVP_R_WRAP_MODE_NOT_ALLOWED:170:wrap mode not allowed
 EVP_R_WRONG_FINAL_BLOCK_LENGTH:109:wrong final block length
+EVP_R_XTS_DUPLICATED_KEYS:183:xts duplicated keys
 KDF_R_INVALID_DIGEST:100:invalid digest
 KDF_R_MISSING_ITERATION_COUNT:109:missing iteration count
 KDF_R_MISSING_KEY:104:missing key
diff --git a/crypto/evp/e_aes.c b/crypto/evp/e_aes.c
index 68322e1982b883d9ca4291410ad502637f2ec983..e60d736b9c57fe02a6b885cf368b693841ca261d 100644
--- a/crypto/evp/e_aes.c
+++ b/crypto/evp/e_aes.c
@@ -59,6 +59,12 @@ typedef struct {
                     const unsigned char iv[16]);
 } EVP_AES_XTS_CTX;
 
+#ifdef FIPS_MODE
+static const int allow_insecure_decrypt = 0;
+#else
+static const int allow_insecure_decrypt = 1;
+#endif
+
 typedef struct {
     union {
         double align;
@@ -383,10 +389,27 @@ static int aesni_xts_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
                               const unsigned char *iv, int enc)
 {
     EVP_AES_XTS_CTX *xctx = EVP_C_DATA(EVP_AES_XTS_CTX,ctx);
+
     if (!iv && !key)
         return 1;
 
     if (key) {
+        /* The key is two half length keys in reality */
+        const int bytes = EVP_CIPHER_CTX_key_length(ctx) / 2;
+        const int bits = bytes * 8;
+
+        /*
+         * Verify that the two keys are different.
+         * 
+         * This addresses Rogaway's vulnerability.
+         * See comment in aes_xts_init_key() below.
+         */
+        if ((!allow_insecure_decrypt || enc)
+                && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
+            EVPerr(EVP_F_AESNI_XTS_INIT_KEY, EVP_R_XTS_DUPLICATED_KEYS);
+            return 0;
+        }
+
         /* key_len is two AES keys */
         if (enc) {
             aesni_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 4,
@@ -787,11 +810,27 @@ static int aes_t4_xts_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
                                const unsigned char *iv, int enc)
 {
     EVP_AES_XTS_CTX *xctx = EVP_C_DATA(EVP_AES_XTS_CTX,ctx);
+
     if (!iv && !key)
         return 1;
 
     if (key) {
-        int bits = EVP_CIPHER_CTX_key_length(ctx) * 4;
+        /* The key is two half length keys in reality */
+        const int bytes = EVP_CIPHER_CTX_key_length(ctx) / 2;
+        const int bits = bytes * 8;
+
+        /*
+         * Verify that the two keys are different.
+         * 
+         * This addresses Rogaway's vulnerability.
+         * See comment in aes_xts_init_key() below.
+         */
+        if ((!allow_insecure_decrypt || enc)
+                && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
+            EVPerr(EVP_F_AES_T4_XTS_INIT_KEY, EVP_R_XTS_DUPLICATED_KEYS);
+            return 0;
+        }
+
         xctx->stream = NULL;
         /* key_len is two AES keys */
         if (enc) {
@@ -3284,10 +3323,12 @@ BLOCK_CIPHER_custom(NID_aes, 128, 1, 12, gcm, GCM,
 
 static int aes_xts_ctrl(EVP_CIPHER_CTX *c, int type, int arg, void *ptr)
 {
-    EVP_AES_XTS_CTX *xctx = EVP_C_DATA(EVP_AES_XTS_CTX,c);
+    EVP_AES_XTS_CTX *xctx = EVP_C_DATA(EVP_AES_XTS_CTX, c);
+
     if (type == EVP_CTRL_COPY) {
         EVP_CIPHER_CTX *out = ptr;
         EVP_AES_XTS_CTX *xctx_out = EVP_C_DATA(EVP_AES_XTS_CTX,out);
+
         if (xctx->xts.key1) {
             if (xctx->xts.key1 != &xctx->ks1)
                 return 0;
@@ -3311,11 +3352,38 @@ static int aes_xts_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,
                             const unsigned char *iv, int enc)
 {
     EVP_AES_XTS_CTX *xctx = EVP_C_DATA(EVP_AES_XTS_CTX,ctx);
+
     if (!iv && !key)
         return 1;
 
     if (key)
         do {
+            /* The key is two half length keys in reality */
+            const int bytes = EVP_CIPHER_CTX_key_length(ctx) / 2;
+            const int bits = bytes * 8;
+
+            /*
+             * Verify that the two keys are different.
+             *
+             * This addresses the vulnerability described in Rogaway's
+             * September 2004 paper:
+             *
+             *      "Efficient Instantiations of Tweakable Blockciphers and
+             *       Refinements to Modes OCB and PMAC".
+             *      (http://web.cs.ucdavis.edu/~rogaway/papers/offsets.pdf)
+             *
+             * FIPS 140-2 IG A.9 XTS-AES Key Generation Requirements states
+             * that:
+             *      "The check for Key_1 != Key_2 shall be done at any place
+             *       BEFORE using the keys in the XTS-AES algorithm to process
+             *       data with them."
+             */
+            if ((!allow_insecure_decrypt || enc)
+                    && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
+                EVPerr(EVP_F_AES_XTS_INIT_KEY, EVP_R_XTS_DUPLICATED_KEYS);
+                return 0;
+            }
+
 #ifdef AES_XTS_ASM
             xctx->stream = enc ? AES_xts_encrypt : AES_xts_decrypt;
 #else
diff --git a/crypto/evp/evp_err.c b/crypto/evp/evp_err.c
index 60df27cbc20ac6f5841c63dc284ea52792eb1cf9..40ed0d902f0971b22237f4c09193794b6810e2f8 100644
--- a/crypto/evp/evp_err.c
+++ b/crypto/evp/evp_err.c
@@ -1,6 +1,6 @@
 /*
  * Generated by util/mkerr.pl DO NOT EDIT
- * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -15,11 +15,15 @@
 
 static const ERR_STRING_DATA EVP_str_functs[] = {
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AESNI_INIT_KEY, 0), "aesni_init_key"},
+    {ERR_PACK(ERR_LIB_EVP, EVP_F_AESNI_XTS_INIT_KEY, 0), "aesni_xts_init_key"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_GCM_CTRL, 0), "aes_gcm_ctrl"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_INIT_KEY, 0), "aes_init_key"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_OCB_CIPHER, 0), "aes_ocb_cipher"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_T4_INIT_KEY, 0), "aes_t4_init_key"},
+    {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_T4_XTS_INIT_KEY, 0),
+     "aes_t4_xts_init_key"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_WRAP_CIPHER, 0), "aes_wrap_cipher"},
+    {ERR_PACK(ERR_LIB_EVP, EVP_F_AES_XTS_INIT_KEY, 0), "aes_xts_init_key"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_ALG_MODULE_INIT, 0), "alg_module_init"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_ARIA_CCM_INIT_KEY, 0), "aria_ccm_init_key"},
     {ERR_PACK(ERR_LIB_EVP, EVP_F_ARIA_GCM_CTRL, 0), "aria_gcm_ctrl"},
@@ -266,6 +270,8 @@ static const ERR_STRING_DATA EVP_str_reasons[] = {
     "wrap mode not allowed"},
     {ERR_PACK(ERR_LIB_EVP, 0, EVP_R_WRONG_FINAL_BLOCK_LENGTH),
     "wrong final block length"},
+    {ERR_PACK(ERR_LIB_EVP, 0, EVP_R_XTS_DUPLICATED_KEYS),
+    "xts duplicated keys"},
     {0, NULL}
 };
 
diff --git a/include/openssl/evperr.h b/include/openssl/evperr.h
index 84f03eb3c45f081de4cccb9e95a7f3c9e73667e1..0a5b7e24f335396c824b7828b35174017e35379a 100644
--- a/include/openssl/evperr.h
+++ b/include/openssl/evperr.h
@@ -1,6 +1,6 @@
 /*
  * Generated by util/mkerr.pl DO NOT EDIT
- * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -20,11 +20,14 @@ int ERR_load_EVP_strings(void);
  * EVP function codes.
  */
 # define EVP_F_AESNI_INIT_KEY                             165
+# define EVP_F_AESNI_XTS_INIT_KEY                         207
 # define EVP_F_AES_GCM_CTRL                               196
 # define EVP_F_AES_INIT_KEY                               133
 # define EVP_F_AES_OCB_CIPHER                             169
 # define EVP_F_AES_T4_INIT_KEY                            178
+# define EVP_F_AES_T4_XTS_INIT_KEY                        208
 # define EVP_F_AES_WRAP_CIPHER                            170
+# define EVP_F_AES_XTS_INIT_KEY                           209
 # define EVP_F_ALG_MODULE_INIT                            177
 # define EVP_F_ARIA_CCM_INIT_KEY                          175
 # define EVP_F_ARIA_GCM_CTRL                              197
@@ -190,5 +193,6 @@ int ERR_load_EVP_strings(void);
 # define EVP_R_UNSUPPORTED_SALT_TYPE                      126
 # define EVP_R_WRAP_MODE_NOT_ALLOWED                      170
 # define EVP_R_WRONG_FINAL_BLOCK_LENGTH                   109
+# define EVP_R_XTS_DUPLICATED_KEYS                        183
 
 #endif
diff --git a/test/recipes/30-test_evp_data/evpciph.txt b/test/recipes/30-test_evp_data/evpciph.txt
index 68eddca7b72844d63ee944340ec28c63dedbaf40..634b63346c11d0f4727073573a5ab1ef368b1526 100644
--- a/test/recipes/30-test_evp_data/evpciph.txt
+++ b/test/recipes/30-test_evp_data/evpciph.txt
@@ -1190,7 +1190,28 @@ Result = CIPHERFINAL_ERROR
 
 Title = AES XTS test vectors from IEEE Std 1619-2007
 
+# Using the same key twice for encryption is always banned.
 Cipher = aes-128-xts
+Operation = ENCRYPT
+Key = 0000000000000000000000000000000000000000000000000000000000000000
+IV = 00000000000000000000000000000000
+Plaintext = 0000000000000000000000000000000000000000000000000000000000000000
+Ciphertext = 917cf69ebd68b2ec9b9fe9a3eadda692cd43d2f59598ed858c02c2652fbf922e
+
+# Using the same key twice for decryption is banned in FIPS mode.
+#Cipher = aes-128-xts
+#FIPS = YES
+#Operation = DECRYPT
+#Key = 0000000000000000000000000000000000000000000000000000000000000000
+#IV = 00000000000000000000000000000000
+#Plaintext = 0000000000000000000000000000000000000000000000000000000000000000
+#Ciphertext = 917cf69ebd68b2ec9b9fe9a3eadda692cd43d2f59598ed858c02c2652fbf922e
+#Result = KEY_SET_ERROR
+
+# Using the same key twice for decryption is allowed outside of FIPS mode.
+Cipher = aes-128-xts
+#FIPS = NO
+Operation = DECRYPT
 Key = 0000000000000000000000000000000000000000000000000000000000000000
 IV = 00000000000000000000000000000000
 Plaintext = 0000000000000000000000000000000000000000000000000000000000000000