mirrors/monero
1
0
Fork 0
mirror of https://github.com/monero-project/monero.git synced 2026-01-30 16:24:54 +01:00
Code Issues Projects Releases Wiki Activity

ringct: encode 8 byte amount, saving 24 bytes per output

Browse Source 
Found by knaccc
This commit is contained in:
moneromooo-monero
2019-01-06 19:49:52 +00:00
parent 77f8f45459
commit 6ba3a11637
14 changed files with 93 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
src/ringct/rctOps.cpp
View File

@@ -487,18 +487,38 @@ namespace rct {
//Elliptic Curve Diffie Helman: encodes and decodes the amount b and mask a
// where C= aG + bH
void ecdhEncode(ecdhTuple & unmasked, const key & sharedSec) {
static key ecdhHash(const key &k)
{
char data[38];
rct::key hash;
memcpy(data, "amount", 6);
memcpy(data + 6, &k, sizeof(k));
cn_fast_hash(hash, data, sizeof(data));
return hash;
}
static void xor8(key &v, const key &k)
{
for (int i = 0; i < 8; ++i)
v.bytes[i] ^= k.bytes[i];
}
void ecdhEncode(ecdhTuple & unmasked, const key & sharedSec, bool short_amount) {
key sharedSec1 = hash_to_scalar(sharedSec);
key sharedSec2 = hash_to_scalar(sharedSec1);
//encode
sc_add(unmasked.mask.bytes, unmasked.mask.bytes, sharedSec1.bytes);
sc_add(unmasked.amount.bytes, unmasked.amount.bytes, sharedSec2.bytes);
if (short_amount)
xor8(unmasked.amount, ecdhHash(sharedSec));
else
sc_add(unmasked.amount.bytes, unmasked.amount.bytes, sharedSec2.bytes);
}
void ecdhDecode(ecdhTuple & masked, const key & sharedSec) {
void ecdhDecode(ecdhTuple & masked, const key & sharedSec, bool short_amount) {
key sharedSec1 = hash_to_scalar(sharedSec);
key sharedSec2 = hash_to_scalar(sharedSec1);
//decode
sc_sub(masked.mask.bytes, masked.mask.bytes, sharedSec1.bytes);
sc_sub(masked.amount.bytes, masked.amount.bytes, sharedSec2.bytes);
if (short_amount)
xor8(masked.amount, ecdhHash(sharedSec));
else
sc_sub(masked.amount.bytes, masked.amount.bytes, sharedSec2.bytes);
}
}