more docs

readme.md

@@ -4,18 +4,42 @@ Ed25519
 This is a portable implementation of [Ed25519](http://ed25519.cr.yp.to/). All
 code is in the public domain.
 
-No code uses libc, except for the random seed generation which uses standard
+All code is pure ANSI C without any dependencies, except for the random seed
-OS cryptography APIs. If you wish to be entirely portable define
+generation which uses standard OS cryptography APIs. If you wish to be
-`ED25519_NO_SEED`. This does disable the `ed25519_create_seed` function
+entirely portable define `ED25519_NO_SEED`. This does disable the
-however.
+`ed25519_create_seed` function however (you can use your own seeding function
+if you wish.)
 
 Usage
 -----
 
-Simply add all .c and .h files in the src/ folder to your project and include
+Simply add all .c and .h files in the `src/` folder to your project and
-ed25519.h. If you prefer to use a shared library, only copy `ed25519.h` and define
+include `ed25519.h` in any file you want to use the API. If you prefer to use
-`ED25519_DLL` before importing. A windows DLL is pre-built.
+a shared library, only copy `ed25519.h` and define `ED25519_DLL` before
+importing. A windows DLL is pre-built.
 
-The API is simple:
+There are no defined types for seeds, signing keys, verifying keys or
+signatures. Instead simple `unsigned char` buffers are used with the following
+sizes:
 
-    int ED25519_DECLSPEC ed25519_create_seed(unsigned char *seed);
+    unsigned char seed[32]
+    unsigned char signature[64]
+    unsigned char verify_key[32]
+    unsigned char signing_key[64]
+
+API
+---
+
+    int ed25519_create_seed(unsigned char *seed);
+
+Creates a 32 byte random seed in `seed` for key generation. `seed` must be a
+writable 32 byte buffer.
+
+    int ed25519_create_keypair(unsigned char *verify_key, unsigned char *sign_key, const unsigned char *seed);
+
+Creates a new key pair from the given seed. `verify_key` must be a writable 32
+byte buffer, `sign_key` must be a writable 64 byte buffer and `seed` must be a
+32 byte buffer.
+
+    int ed25519_sign(unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *sign_key);
+    int ed25519_verify(const unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *verify_key);

src/ed25519.h

@@ -24,7 +24,7 @@ extern "C" {
 int ED25519_DECLSPEC ed25519_create_seed(unsigned char *seed);
 #endif
 
-int ED25519_DECLSPEC ed25519_create_keypair(unsigned char *verify_key, unsigned char *sign_key, unsigned char *seed);
+int ED25519_DECLSPEC ed25519_create_keypair(unsigned char *verify_key, unsigned char *sign_key, const unsigned char *seed);
 int ED25519_DECLSPEC ed25519_sign(unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *sign_key);
 int ED25519_DECLSPEC ed25519_verify(const unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *verify_key);
 

src/keypair.c

@@ -3,7 +3,7 @@
 #include "ge.h"
 
 
-int ed25519_create_keypair(unsigned char *verify_key, unsigned char *sign_key, unsigned char *seed) {
+int ed25519_create_keypair(unsigned char *verify_key, unsigned char *sign_key, const unsigned char *seed) {
     unsigned char h[64];
     ge_p3 A;
     int i;