40 lines
1.2 KiB
Text
40 lines
1.2 KiB
Text
See http://code.google.com/p/curve25519-donna/ for details.
|
|
|
|
BUILDING:
|
|
|
|
If you run `make`, two .a archives will be built, similar to djb's curve25519
|
|
code. Alternatively, read on:
|
|
|
|
The C implementation is contained within curve25519-donna.c. It has no external
|
|
dependancies and is BSD licenced. You can copy/include/link it directly in with
|
|
your program. Recommended C flags: -O2
|
|
|
|
The x86-64 bit implementation is contained within curve25519-donna-x86-64.c and
|
|
curve25519-donna-x86-64.s. Build like this:
|
|
|
|
% cpp curve25519-donna-x86-64.s > curve25519-donna-x86-64.s.pp
|
|
% as -o curve25519-donna-x86-64.s.o curve25519-donna-x86-64.s.pp
|
|
% gcc -O2 -c curve25519-donna-x86-64.c
|
|
|
|
Then the two .o files can be linked in
|
|
|
|
USAGE:
|
|
|
|
The usage is exactly the same as djb's code (as described at
|
|
http://cr.yp.to/ecdh.html) expect that the function is called curve25519_donna.
|
|
|
|
In short,
|
|
|
|
To generate a private key just generate 32 random bytes.
|
|
|
|
To generate the public key, just do:
|
|
|
|
static const uint8_t basepoint[32] = {9};
|
|
curve25519_donna(mypublic, mysecret, basepoint);
|
|
|
|
To generate an agreed key do:
|
|
|
|
uint8_t shared_key[32];
|
|
curve25519_donna(shared_key, mysecret, theirpublic);
|
|
|
|
And hash the shared_key with a cryptographic hash function before using.
|