updated Crypto.md and added information to Building.md

doc/Building.md

@@ -111,4 +111,16 @@ Pearson Hashing:   AES-NI
 
 The compilations flags could easily be combined:
 
-`./configure CFLAGS="-O3 -march=native"`.
+`./configure CFLAGS="-O3 -march=native"`.
+
+## OpenSSL Support
+
+Some ciphers' speed can take advantage of OpenSSL support which is disabled by default as the built-in ciphers already prove reasonably fast in most cases. OpenSSL support can be configured using
+
+`./configure --with-openssl`
+
+which then will include OpenSSL 1.0 or 1.1 if found on the system. This can be combined with the hardware support and compiler optimizations such as
+
+`./configure --with-openssl CFLAGS="-O3 -march=native"`
+
+Please do no forget to `make clean` after (re-)configuration and before building using `make`.

doc/Crypto.md

@@ -24,7 +24,7 @@ The following chart might help to make a quick comparison and decide what cipher
 
 The two block ciphers Twofish and AES are used in CTS mode.
 
-n2n has all four ciphers built-in as basic versions. Some of them optionally compile to faster versions by the means of available hardware support (AES-NI, SSE, AVX – please see the [Building document](./Building.md) for details. Also, AES and ChaCha20 might draw notable acceleration from compiling with openSSL 1.1 support.
+n2n has all four ciphers built-in as basic versions. Some of them optionally compile to faster versions by the means of available hardware support (AES-NI, SSE, AVX – please see the [Building document](./Building.md) for details. Depending on your platform, AES and ChaCha20 might also draw notable acceleration from optionally compiling with openSSL 1.1 support.
 
 ### Twofish