diff options
Diffstat (limited to 'libs/libaxolotl/src/curve25519/ed25519/additions/sc_neg.c')
| -rw-r--r-- | libs/libaxolotl/src/curve25519/ed25519/additions/sc_neg.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/libs/libaxolotl/src/curve25519/ed25519/additions/sc_neg.c b/libs/libaxolotl/src/curve25519/ed25519/additions/sc_neg.c new file mode 100644 index 0000000000..ef407d405e --- /dev/null +++ b/libs/libaxolotl/src/curve25519/ed25519/additions/sc_neg.c @@ -0,0 +1,25 @@ +#include <string.h> +#include "crypto_additions.h" +#include "sc.h" + +/* l = order of base point = 2^252 + 27742317777372353535851937790883648493 */ + +/* +static unsigned char l[32] = {0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, + 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0, 0x10}; +*/ + +static unsigned char lminus1[32] = {0xec, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58, + 0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10}; + +/* b = -a (mod l) */ +void sc_neg(unsigned char *b, const unsigned char *a) +{ + unsigned char zero[32]; + memset(zero, 0, 32); + sc_muladd(b, lminus1, a, zero); /* b = (-1)a + 0 (mod l) */ +} |