olm/lib/ed25519_additions.c

43 lines
1 KiB
C

void convert_curve25519_to_ed25519(
unsigned char * public_key,
unsigned char * signature
) {
fe mont_x, mont_x_minus_one, mont_x_plus_one, inv_mont_x_plus_one;
fe one;
fe ed_y;
fe_frombytes(mont_x, public_key);
fe_1(one);
fe_sub(mont_x_minus_one, mont_x, one);
fe_add(mont_x_plus_one, mont_x, one);
fe_invert(inv_mont_x_plus_one, mont_x_plus_one);
fe_mul(ed_y, mont_x_minus_one, inv_mont_x_plus_one);
fe_tobytes(public_key, ed_y);
public_key[31] &= 0x7F;
public_key[31] |= (signature[63] & 0x80);
signature[63] &= 0x7F;
}
void convert_ed25519_to_curve25519(
unsigned char const * public_key,
unsigned char * signature
) {
unsigned char sign_bit = public_key[31] & 0x80;
signature[63] &= 0x7F;
signature[63] |= sign_bit;
}
void ed25519_keypair(
unsigned char * private_key,
unsigned char * public_key
) {
ge_p3 A;
private_key[0] &= 248;
private_key[31] &= 63;
private_key[31] |= 64;
ge_scalarmult_base(&A, private_key);
ge_p3_tobytes(public_key, &A);
}