diff --git a/decrepit/CMakeLists.txt b/decrepit/CMakeLists.txt
index 0829926..ef95a6b 100644
--- a/decrepit/CMakeLists.txt
+++ b/decrepit/CMakeLists.txt
@@ -33,6 +33,7 @@
   cast/cast_test.cc
   cfb/cfb_test.cc
   ripemd/ripemd_test.cc
+  xts/xts_test.cc
 
   $<TARGET_OBJECTS:boringssl_gtest_main>
 )
diff --git a/decrepit/xts/xts_test.cc b/decrepit/xts/xts_test.cc
new file mode 100644
index 0000000..22e80fa
--- /dev/null
+++ b/decrepit/xts/xts_test.cc
@@ -0,0 +1,268 @@
+// Copyright (c) 2020, Google Inc.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/cipher.h>
+
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "../../crypto/internal.h"
+#include "../../crypto/test/test_util.h"
+
+
+struct XTSTestCase {
+  const char *key_hex;
+  const char *iv_hex;
+  const char *plaintext_hex;
+  const char *ciphertext_hex;
+};
+
+static const XTSTestCase kXTSTestCases[] = {
+    // Test vectors from OpenSSL 1.1.1d.
+    {
+        "2718281828459045235360287471352662497757247093699959574966967627314159"
+        "2653589793238462643383279502884197169399375105820974944592",
+        "ff000000000000000000000000000000",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122"
+        "232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445"
+        "464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768"
+        "696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b"
+        "8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadae"
+        "afb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1"
+        "d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4"
+        "f5f6f7f8f9fafbfcfdfeff000102030405060708090a0b0c0d0e0f1011121314151617"
+        "18191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a"
+        "3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d"
+        "5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f80"
+        "8182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3"
+        "a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6"
+        "c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9"
+        "eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+        "1c3b3a102f770386e4836c99e370cf9bea00803f5e482357a4ae12d414a3e63b5d31e2"
+        "76f8fe4a8d66b317f9ac683f44680a86ac35adfc3345befecb4bb188fd5776926c49a3"
+        "095eb108fd1098baec70aaa66999a72a82f27d848b21d4a741b0c5cd4d5fff9dac89ae"
+        "ba122961d03a757123e9870f8acf1000020887891429ca2a3e7a7d7df7b10355165c8b"
+        "9a6d0a7de8b062c4500dc4cd120c0f7418dae3d0b5781c34803fa75421c790dfe1de18"
+        "34f280d7667b327f6c8cd7557e12ac3a0f93ec05c52e0493ef31a12d3d9260f79a289d"
+        "6a379bc70c50841473d1a8cc81ec583e9645e07b8d9670655ba5bbcfecc6dc3966380a"
+        "d8fecb17b6ba02469a020a84e18e8f84252070c13e9f1f289be54fbc481457778f6160"
+        "15e1327a02b140f1505eb309326d68378f8374595c849d84f4c333ec4423885143cb47"
+        "bd71c5edae9be69a2ffeceb1bec9de244fbe15992b11b77c040f12bd8f6a975a44a0f9"
+        "0c29a9abc3d4d893927284c58754cce294529f8614dcd2aba991925fedc4ae74ffac6e"
+        "333b93eb4aff0479da9a410e4450e0dd7ae4c6e2910900575da401fc07059f645e8b7e"
+        "9bfdef33943054ff84011493c27b3429eaedb4ed5376441a77ed43851ad77f16f541df"
+        "d269d50d6a5f14fb0aab1cbb4c1550be97f7ab4066193c4caa773dad38014bd2092fa7"
+        "55c824bb5e54c4f36ffda9fcea70b9c6e693e148c151",
+    },
+    {
+        "2718281828459045235360287471352662497757247093699959574966967627314159"
+        "2653589793238462643383279502884197169399375105820974944592",
+        "ffff0000000000000000000000000000",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122"
+        "232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445"
+        "464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768"
+        "696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b"
+        "8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadae"
+        "afb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1"
+        "d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4"
+        "f5f6f7f8f9fafbfcfdfeff000102030405060708090a0b0c0d0e0f1011121314151617"
+        "18191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a"
+        "3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d"
+        "5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f80"
+        "8182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3"
+        "a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6"
+        "c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9"
+        "eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+        "77a31251618a15e6b92d1d66dffe7b50b50bad552305ba0217a610688eff7e11e1d022"
+        "5438e093242d6db274fde801d4cae06f2092c728b2478559df58e837c2469ee4a4fa79"
+        "4e4bbc7f39bc026e3cb72c33b0888f25b4acf56a2a9804f1ce6d3d6e1dc6ca181d4b54"
+        "6179d55544aa7760c40d06741539c7e3cd9d2f6650b2013fd0eeb8c2b8e3d8d240ccae"
+        "2d4c98320a7442e1c8d75a42d6e6cfa4c2eca1798d158c7aecdf82490f24bb9b38e108"
+        "bcda12c3faf9a21141c3613b58367f922aaa26cd22f23d708dae699ad7cb40a8ad0b6e"
+        "2784973dcb605684c08b8d6998c69aac049921871ebb65301a4619ca80ecb485a31d74"
+        "4223ce8ddc2394828d6a80470c092f5ba413c3378fa6054255c6f9df4495862bbb3287"
+        "681f931b687c888abf844dfc8fc28331e579928cd12bd2390ae123cf03818d14dedde5"
+        "c0c24c8ab018bfca75ca096f2d531f3d1619e785f1ada437cab92e980558b3dce1474a"
+        "fb75bfedbf8ff54cb2618e0244c9ac0d3c66fb51598cd2db11f9be39791abe447c6309"
+        "4f7c453b7ff87cb5bb36b7c79efb0872d17058b83b15ab0866ad8a58656c5a7e20dbdf"
+        "308b2461d97c0ec0024a2715055249cf3b478ddd4740de654f75ca686e0d7345c69ed5"
+        "0cdc2a8b332b1f8824108ac937eb050585608ee734097fc09054fbff89eeaeea791f4a"
+        "7ab1f9868294a4f9e27b42af8100cb9d59cef9645803",
+    },
+    {
+        "2718281828459045235360287471352662497757247093699959574966967627314159"
+        "2653589793238462643383279502884197169399375105820974944592",
+        "ffffff00000000000000000000000000",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122"
+        "232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445"
+        "464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768"
+        "696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b"
+        "8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadae"
+        "afb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1"
+        "d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4"
+        "f5f6f7f8f9fafbfcfdfeff000102030405060708090a0b0c0d0e0f1011121314151617"
+        "18191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a"
+        "3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d"
+        "5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f80"
+        "8182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3"
+        "a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6"
+        "c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9"
+        "eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+        "e387aaa58ba483afa7e8eb469778317ecf4cf573aa9d4eac23f2cdf914e4e200a8b490"
+        "e42ee646802dc6ee2b471b278195d60918ececb44bf79966f83faba0499298ebc699c0"
+        "c8634715a320bb4f075d622e74c8c932004f25b41e361025b5a87815391f6108fc4afa"
+        "6a05d9303c6ba68a128a55705d415985832fdeaae6c8e19110e84d1b1f199a2692119e"
+        "dc96132658f09da7c623efcec712537a3d94c0bf5d7e352ec94ae5797fdb377dc15511"
+        "50721adf15bd26a8efc2fcaad56881fa9e62462c28f30ae1ceaca93c345cf243b73f54"
+        "2e2074a705bd2643bb9f7cc79bb6e7091ea6e232df0f9ad0d6cf502327876d82207abf"
+        "2115cdacf6d5a48f6c1879a65b115f0f8b3cb3c59d15dd8c769bc014795a1837f3901b"
+        "5845eb491adfefe097b1fa30a12fc1f65ba22905031539971a10f2f36c321bb51331cd"
+        "efb39e3964c7ef079994f5b69b2edd83a71ef549971ee93f44eac3938fcdd61d01fa71"
+        "799da3a8091c4c48aa9ed263ff0749df95d44fef6a0bb578ec69456aa5408ae32c7af0"
+        "8ad7ba8921287e3bbee31b767be06a0e705c864a769137df28292283ea81a2480241b4"
+        "4d9921cdbec1bc28dc1fda114bd8e5217ac9d8ebafa720e9da4f9ace231cc949e5b96f"
+        "e76ffc21063fddc83a6b8679c00d35e09576a875305bed5f36ed242c8900dd1fa965bc"
+        "950dfce09b132263a1eef52dd6888c309f5a7d712826",
+    },
+    {
+        "2718281828459045235360287471352662497757247093699959574966967627314159"
+        "2653589793238462643383279502884197169399375105820974944592",
+        "ffffffff000000000000000000000000",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122"
+        "232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445"
+        "464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768"
+        "696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b"
+        "8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadae"
+        "afb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1"
+        "d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4"
+        "f5f6f7f8f9fafbfcfdfeff000102030405060708090a0b0c0d0e0f1011121314151617"
+        "18191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a"
+        "3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d"
+        "5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f80"
+        "8182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3"
+        "a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6"
+        "c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9"
+        "eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+        "bf53d2dade78e822a4d949a9bc6766b01b06a8ef70d26748c6a7fc36d80ae4c5520f7c"
+        "4ab0ac8544424fa405162fef5a6b7f229498063618d39f0003cb5fb8d1c86b643497da"
+        "1ff945c8d3bedeca4f479702a7a735f043ddb1d6aaade3c4a0ac7ca7f3fa5279bef56f"
+        "82cd7a2f38672e824814e10700300a055e1630b8f1cb0e919f5e942010a416e2bf48cb"
+        "46993d3cb6a51c19bacf864785a00bc2ecff15d350875b246ed53e68be6f55bd7e05cf"
+        "c2b2ed6432198a6444b6d8c247fab941f569768b5c429366f1d3f00f0345b96123d562"
+        "04c01c63b22ce78baf116e525ed90fdea39fa469494d3866c31e05f295ff21fea8d4e6"
+        "e13d67e47ce722e9698a1c1048d68ebcde76b86fcf976eab8aa9790268b7068e017a8b"
+        "9b749409514f1053027fd16c3786ea1bac5f15cb79711ee2abe82f5cf8b13ae73030ef"
+        "5b9e4457e75d1304f988d62dd6fc4b94ed38ba831da4b7634971b6cd8ec325d9c61c00"
+        "f1df73627ed3745a5e8489f3a95c69639c32cd6e1d537a85f75cc844726e8a72fc0077"
+        "ad22000f1d5078f6b866318c668f1ad03d5a5fced5219f2eabbd0aa5c0f460d183f044"
+        "04a0d6f469558e81fab24a167905ab4c7878502ad3e38fdbe62a41556cec3732575953"
+        "3ce8f25f367c87bb5578d667ae93f9e2fd99bcbc5f2fbba88cf6516139420fcff3b736"
+        "1d86322c4bd84c82f335abb152c4a93411373aaa8220",
+    },
+    {
+        "2718281828459045235360287471352662497757247093699959574966967627314159"
+        "2653589793238462643383279502884197169399375105820974944592",
+        "ffffffffff0000000000000000000000",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122"
+        "232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445"
+        "464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768"
+        "696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b"
+        "8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadae"
+        "afb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1"
+        "d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4"
+        "f5f6f7f8f9fafbfcfdfeff000102030405060708090a0b0c0d0e0f1011121314151617"
+        "18191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a"
+        "3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d"
+        "5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f80"
+        "8182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3"
+        "a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6"
+        "c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9"
+        "eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff",
+        "64497e5a831e4a932c09be3e5393376daa599548b816031d224bbf50a818ed2350eae7"
+        "e96087c8a0db51ad290bd00c1ac1620857635bf246c176ab463be30b808da548081ac8"
+        "47b158e1264be25bb0910bbc92647108089415d45fab1b3d2604e8a8eff1ae4020cfa3"
+        "9936b66827b23f371b92200be90251e6d73c5f86de5fd4a950781933d79a28272b782a"
+        "2ec313efdfcc0628f43d744c2dc2ff3dcb66999b50c7ca895b0c64791eeaa5f29499fb"
+        "1c026f84ce5b5c72ba1083cddb5ce45434631665c333b60b11593fb253c5179a2c8db8"
+        "13782a004856a1653011e93fb6d876c18366dd8683f53412c0c180f9c848592d593f86"
+        "09ca736317d356e13e2bff3a9f59cd9aeb19cd482593d8c46128bb32423b37a9adfb48"
+        "2b99453fbe25a41bf6feb4aa0bef5ed24bf73c762978025482c13115e4015aac992e56"
+        "13a3b5c2f685b84795cb6e9b2656d8c88157e52c42f978d8634c43d06fea928f2822e4"
+        "65aa6576e9bf419384506cc3ce3c54ac1a6f67dc66f3b30191e698380bc999b05abce1"
+        "9dc0c6dcc2dd001ec535ba18deb2df1a101023108318c75dc98611a09dc48a0acdec67"
+        "6fabdf222f07e026f059b672b56e5cbc8e1d21bbd867dd927212054681d70ea737134c"
+        "dfce93b6f82ae22423274e58a0821cc5502e2d0ab4585e94de6975be5e0b4efce51cd3"
+        "e70c25a1fbbbd609d273ad5b0d59631c531f6a0a57b9",
+    },
+};
+
+TEST(XTSTest, TestVectors) {
+  unsigned test_num = 0;
+  for (const auto &test : kXTSTestCases) {
+    test_num++;
+    SCOPED_TRACE(test_num);
+
+    const EVP_CIPHER *cipher = EVP_aes_256_xts();
+
+    std::vector<uint8_t> key, iv, plaintext, ciphertext;
+    ASSERT_TRUE(DecodeHex(&key, test.key_hex));
+    ASSERT_TRUE(DecodeHex(&iv, test.iv_hex));
+    ASSERT_TRUE(DecodeHex(&plaintext, test.plaintext_hex));
+    ASSERT_TRUE(DecodeHex(&ciphertext, test.ciphertext_hex));
+
+    ASSERT_EQ(EVP_CIPHER_key_length(cipher), key.size());
+    ASSERT_EQ(EVP_CIPHER_iv_length(cipher), iv.size());
+    ASSERT_EQ(plaintext.size(), ciphertext.size());
+
+    // Note XTS doesn't support streaming, so we only test single-shot inputs.
+    for (bool in_place : {false, true}) {
+      SCOPED_TRACE(in_place);
+
+      // Test encryption.
+      bssl::Span<const uint8_t> in = plaintext;
+      std::vector<uint8_t> out(plaintext.size());
+      if (in_place) {
+        out = plaintext;
+        in = out;
+      }
+
+      bssl::ScopedEVP_CIPHER_CTX ctx;
+      ASSERT_TRUE(EVP_EncryptInit_ex(ctx.get(), cipher, nullptr, key.data(),
+                                     iv.data()));
+      int len;
+      ASSERT_TRUE(
+          EVP_EncryptUpdate(ctx.get(), out.data(), &len, in.data(), in.size()));
+      out.resize(len);
+      EXPECT_EQ(Bytes(ciphertext), Bytes(out));
+
+      // Test decryption.
+      in = ciphertext;
+      out.clear();
+      out.resize(plaintext.size());
+      if (in_place) {
+        out = ciphertext;
+        in = out;
+      }
+
+      ctx.Reset();
+      ASSERT_TRUE(EVP_DecryptInit_ex(ctx.get(), cipher, nullptr, key.data(),
+                                     iv.data()));
+      ASSERT_TRUE(
+          EVP_DecryptUpdate(ctx.get(), out.data(), &len, in.data(), in.size()));
+      out.resize(len);
+      EXPECT_EQ(Bytes(plaintext), Bytes(out));
+    }
+  }
+}