Implement AES-XTS mode
XTS mode is fully known as "xor-encrypt-xor with ciphertext-stealing".
This is the generalization of the XEX mode.
This implementation is limited to an 8-bits (1 byte) boundary, which
doesn't seem to be what was thought considering some test vectors [1].
This commit comes with tests, extracted from [1], and benchmarks.
Although, benchmarks aren't really nice here, as they work with a buffer
of a multiple of 16 bytes, which isn't a challenge for XTS compared to
XEX.
[1] http://csrc.nist.gov/groups/STM/cavp/documents/aes/XTSTestVectors.zip
diff --git a/library/version_features.c b/library/version_features.c
index 0b7c0af..fd932f1 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -252,6 +252,9 @@
#if defined(MBEDTLS_CIPHER_MODE_XEX)
"MBEDTLS_CIPHER_MODE_XEX",
#endif /* MBEDTLS_CIPHER_MODE_XEX */
+#if defined(MBEDTLS_CIPHER_MODE_XTS)
+ "MBEDTLS_CIPHER_MODE_XTS",
+#endif /* MBEDTLS_CIPHER_MODE_XTS */
#if defined(MBEDTLS_CIPHER_MODE_OFB)
"MBEDTLS_CIPHER_MODE_OFB",
#endif /* MBEDTLS_CIPHER_MODE_OFB */