More blurb

README.markdown

@@ -1,8 +1,69 @@
-# libsodium - P(ortable|ackageable) NaCl
+# libsodium
 
-Portable, cross-compilable, installable, packageable version of the NaCl
-crypto library.
+[NaCl](http://nacl.cr.yp.to/) (pronounced "salt") is a new easy-to-use
+high-speed software library for network communication, encryption,
+decryption, signatures, etc.
 
-## comparison with vanilla NaCl
+NaCl's goal is to provide all of the core operations needed to build
+higher-level cryptographic tools.
+
+Sodium is a portable, cross-compilable, installable, packageable
+version of NaCl, binary-compatible with NaCl.
+
+## Portable
+
+In order to pick the fastest working implementation of each primitive,
+NaCl performs tests and benchmarks at compile-time. Unfortunately, the
+resulting library is not garanteed to work on different hardware.
+
+Sodium currently only ships portable reference implementations.
+
+Optimized implementations (including NEON optimizations) will eventually
+be supported, but tests and benchmarks will be performed at run-time,
+so that the same binary package can still run everywhere.
+
+Sodium is tested on a variety of compilers and operating systems,
+including Windows, iOS and Android.
+
+## Installable
+
+Sodium is a shared library with a machine-independant set of
+headers, so that it can easily be used by 3rd party projects.
+
+The library is built using autotools, making it easy to package.
+
+Installation is trivial, and both compilation and testing can take
+advantage of multiple CPU cores:
+
+    ./configure
+    make
+    make check
+    make install
+
+## Comparison with vanilla NaCl
+
+The default public-key signature system in NaCl was a prototype that
+shouldn't be used any more.
+
+Sodium ships with the SUPERCOP reference implementation of
+[Ed25519](http://ed25519.cr.yp.to/), and uses this system by default
+for `crypto_sign*` operations.
+
+For backward compatibility, the previous system is still compiled in,
+as `crypto_sign_edwards25519sha512batch*`.
+
+## Additional features
+
+The Sodium library provides some convenience functions in order to retrieve
+the current version of the library:
+
+    const char *sodium_version_string(void);
+    const int   sodium_version_major(void);
+    const int   sodium_version_minor(void);
+
+Headers are installed in `${prefix}/include/sodium`.
+
+A convenience header includes everything you need to use the library:
+
+    #include <sodium.h>
 
-We are using ed25519 from SUPERCOP, as even DJB doesn't recommend using edwards25519sha512batch anymore - this will reach NaCL one day...