Code cleanup and rearranging things for future work. Added support for 192 and 256-bit curves.

asm_avr.inc

@@ -0,0 +1 @@
+/* TODO small implementation */

ecc.h

@@ -3,38 +3,50 @@
 
 #include <stdint.h>
 
-/* Optimization settings. Define as 1 to enable an optimization, 0 to disable it.
-ECC_SQUARE_FUNC - If enabled, this will cause a specific function to be used for (scalar) squaring instead of the generic
-                  multiplication function.
-*/
-#define ECC_SQUARE_FUNC 1
+/* Platform selection options.
+If ECC_PLATFORM is not defined, the code will try to guess it based on compiler macros.
+Possible values for ECC_PLATFORM are defined below: */
+#define ecc_arch_other 0
+#define ecc_x86        1
+#define ecc_x86_64     2
+#define ecc_arm        3
+#define ecc_arm_thumb  4
+#define ecc_avr        5
+
+/* If desired, you can define ECC_WORD_SIZE as appropriate for your platform (1, 4, or 8 bytes).
+If ECC_WORD_SIZE is not explicitly defined then it will be automatically set based on your platform. */
 
 /* Inline assembly options.
-Inline assembly (gcc format) is provided for selected operations for AVR (requires MUL support).
-*/
-#define ecc_asm_none   0
-#define ecc_asm_avr    1
+ecc_asm_none  - Use standard C99 only.
+ecc_asm_small - Use GCC inline assembly for the target platform (if available), optimized for minimum size.
+ecc_asm_fast  - Use GCC inline assembly optimized for maximum speed. */
+#define ecc_asm_none  0
+#define ecc_asm_small 1
+#define ecc_asm_fast  2
 #ifndef ECC_ASM
-    #define ECC_ASM ecc_asm_avr
+    #define ECC_ASM ecc_asm_fast
 #endif
 
+/* Curve selection options. */
+#define secp160r1 1
+#define secp192r1 2
+#define secp256r1 3
+#ifndef ECC_CURVE
+    #define ECC_CURVE secp256r1
+#endif
+
+/* Optimization settings. Define as 1 to enable an optimization, 0 to disable it.
+ECC_SQUARE_FUNC - If enabled, this will cause a specific function to be used for (scalar) squaring instead of the generic
+                  multiplication function. This will make things faster by about 8% but increases the code size. */
+#define ECC_SQUARE_FUNC 1
+
+
 #define ECC_CONCAT1(a, b) a##b
 #define ECC_CONCAT(a, b) ECC_CONCAT1(a, b)
 
-/* Curve selection options. */
-#define secp128r1 1
-#define secp160r1 2
-#define secp192r1 3
-#define secp256r1 4
-
-#ifndef ECC_CURVE
-    #define ECC_CURVE secp160r1
-#endif
-
-#define ecc_size_1 16
-#define ecc_size_2 20
-#define ecc_size_3 24
-#define ecc_size_4 32
+#define ecc_size_1 20 /* secp160r1 */
+#define ecc_size_2 24 /* secp192r1 */
+#define ecc_size_3 32 /* secp256r1 */
 
 #define ECC_BYTES ECC_CONCAT(ecc_size_, ECC_CURVE)
 
@@ -46,6 +58,15 @@ extern "C"
 /* RNG_Function type
 The RNG function should fill p_size random bytes into p_dest. It should return 1 if
 p_dest was filled with random data, or 0 if the random data could not be generated.
+The filled-in values should be either truly random, or from a cryptographically-secure PRNG.
+
+A correctly functioning RNG function must be set (using ecc_set_rng()) before calling
+ecc_make_key() or ecdsa_sign().
+
+A correct RNG function is set by default when building for Windows, Linux, or OS X.
+If you are building on another POSIX-compliant system that supports /dev/random or /dev/urandom,
+you can define ECC_POSIX to use the predefined RNG. For embedded platforms there is no predefined
+RNG function; you must provide your own.
 */
 typedef int (*RNG_Function)(uint8_t *p_dest, unsigned p_size);
 
@@ -53,7 +74,8 @@ typedef int (*RNG_Function)(uint8_t *p_dest, unsigned p_size);
 Set the function that will be used to generate random bytes. The RNG function should
 return 1 if the random data was generated, or 0 if the random data could not be generated.
 
-This must be called before ecc_make_key(), ecdh_shared_secret(), or ecdsa_sign() are used.
+On platforms where there is no predefined RNG function (eg embedded platforms), this must
+be called before ecc_make_key() or ecdsa_sign() are used.
     
 Inputs:
     p_rng  - The function that will be used to generate random bytes.