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Merge pull request #132 from jayden-sudo/develop
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Update FCL_elliptic.sol
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@CodeExplorer29
CodeExplorer29 authored May 16, 2024
2 parents e8a81c7 + 66c475f commit ba55e82
Showing 1 changed file with 31 additions and 30 deletions.
61 changes: 31 additions & 30 deletions contracts/libraries/FCL_elliptic.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ library FCL_Elliptic_ZZ {
* /* inversion mod n via a^(n-2), use of precompiled using little Fermat theorem
*/
function FCL_nModInv(uint256 u) internal view returns (uint256 result) {
assembly {
assembly ("memory-safe") {
let pointer := mload(0x40)
// Define length of base, exponent and modulus. 0x20 == 32 bytes
mstore(pointer, 0x20)
Expand All @@ -67,7 +67,7 @@ library FCL_Elliptic_ZZ {
mstore(add(pointer, 0xa0), n)

// Call the precompiled contract 0x05 = ModExp
if iszero(staticcall(not(0), 0x05, pointer, 0xc0, pointer, 0x20)) { revert(0, 0) }
if iszero(staticcall(gas(), 0x05, pointer, 0xc0, pointer, 0x20)) { revert(0, 0) }
result := mload(pointer)
}
}
Expand All @@ -76,7 +76,7 @@ library FCL_Elliptic_ZZ {
*/

function FCL_pModInv(uint256 u) internal view returns (uint256 result) {
assembly {
assembly ("memory-safe") {
let pointer := mload(0x40)
// Define length of base, exponent and modulus. 0x20 == 32 bytes
mstore(pointer, 0x20)
Expand All @@ -87,8 +87,8 @@ library FCL_Elliptic_ZZ {
mstore(add(pointer, 0x80), minus_2)
mstore(add(pointer, 0xa0), p)

// Call the precompiled contract 0x05 = ModExp ̰
if iszero(staticcall(not(0), 0x05, pointer, 0xc0, pointer, 0x20)) { revert(0, 0) }
// Call the precompiled contract 0x05 = ModExp
if iszero(staticcall(gas(), 0x05, pointer, 0xc0, pointer, 0x20)) { revert(0, 0) }
result := mload(pointer)
}
}
Expand All @@ -113,7 +113,6 @@ library FCL_Elliptic_ZZ {
* @dev Sutherland2008 add a ZZ point with a normalized point and greedy formulae
* warning: assume that P1(x1,y1)!=P2(x2,y2), true in multiplication loop with prime order (cofactor 1)
*/

function ecZZ_AddN(uint256 x1, uint256 y1, uint256 zz1, uint256 zzz1, uint256 x2, uint256 y2)
internal
pure
Expand All @@ -124,7 +123,7 @@ library FCL_Elliptic_ZZ {
return (x2, y2, 1, 1);
}

assembly {
assembly ("memory-safe") {
y1 := sub(p, y1)
y2 := addmod(mulmod(y2, zzz1, p), y1, p)
x2 := addmod(mulmod(x2, zz1, p), sub(p, x1), p)
Expand Down Expand Up @@ -153,7 +152,7 @@ library FCL_Elliptic_ZZ {
* @dev Check if a point in affine coordinates is on the curve (reject Neutral that is indeed on the curve).
*/
function ecAff_isOnCurve(uint256 x, uint256 y) internal pure returns (bool) {
if (0 == x || x == p || 0 == y || y == p) {
if (x >= p || y >= p || ((x == 0) && (y == 0))) {
return false;
}
unchecked {
Expand All @@ -166,9 +165,8 @@ library FCL_Elliptic_ZZ {
}

/**
* @dev Add two elliptic curve points in affine coordinates.
* @dev Add two elliptic curve points in affine coordinates. Deal with P=Q
*/

function ecAff_add(uint256 x0, uint256 y0, uint256 x1, uint256 y1) internal view returns (uint256, uint256) {
uint256 zz0;
uint256 zzz0;
Expand Down Expand Up @@ -204,6 +202,13 @@ library FCL_Elliptic_ZZ {

(H0, H1) = ecAff_add(gx, gy, Q0, Q1); //will not work if Q=P, obvious forbidden private key

if (
(H0 == 0) && (H1 == 0) //handling Q=-G
) {
scalar_u = addmod(scalar_u, n - scalar_v, n);
scalar_v = 0;
if (scalar_u == 0 && scalar_v == 0) return 0;
}
assembly {
for { let T4 := add(shl(1, and(shr(index, scalar_v), 1)), and(shr(index, scalar_u), 1)) } eq(T4, 0) {
index := sub(index, 1)
Expand Down Expand Up @@ -287,13 +292,11 @@ library FCL_Elliptic_ZZ {
T2 := mulmod(T1, T1, p) // V=U^2
T3 := mulmod(X, T2, p) // S = X1*V

let TT1 := mulmod(T1, T2, p) // W=UV
y2 := addmod(X, zz, p)
TT1 := addmod(X, sub(p, zz), p)
y2 := mulmod(y2, TT1, p) //(X-ZZ)(X+ZZ)
T4 := mulmod(3, y2, p) //M
T1 := mulmod(T1, T2, p) // W=UV
y2 := mulmod(addmod(X, zz, p), addmod(X, sub(p, zz), p), p) //(X-ZZ)(X+ZZ)
T4 := mulmod(3, y2, p) //M=3*(X-ZZ)(X+ZZ)

zzz := mulmod(TT1, zzz, p) //zzz3=W*zzz1
zzz := mulmod(T1, zzz, p) //zzz3=W*zzz1
zz := mulmod(T2, zz, p) //zz3=V*ZZ1, V free

X := addmod(mulmod(T4, T4, p), mulmod(minus_2, T3, p), p) //X3=M^2-2S
Expand Down Expand Up @@ -330,7 +333,7 @@ library FCL_Elliptic_ZZ {
mstore(add(T, 0xa0), p)

// Call the precompiled contract 0x05 = ModExp
if iszero(staticcall(not(0), 0x05, T, 0xc0, T, 0x20)) { revert(0, 0) }
if iszero(staticcall(gas(), 0x05, T, 0xc0, T, 0x20)) { revert(0, 0) }

//Y:=mulmod(Y,zzz,p)//Y/zzz
//zz :=mulmod(zz, mload(T),p) //1/z
Expand All @@ -343,13 +346,14 @@ library FCL_Elliptic_ZZ {
}

/**
* @dev ECDSA verification, given , signature, and public key.
* @dev ECDSA verification, given , signature, and public key, no calldata version
*/
function ecdsa_verify(bytes32 message, uint256 r, uint256 s, uint256 Q0, uint256 Q1) internal view returns (bool) {
function ecdsa_verify(bytes32 message, uint256 r, uint256 s, uint256 Qx, uint256 Qy) internal view returns (bool) {
if (r == 0 || r >= n || s == 0 || s >= n) {
return false;
}
if (!ecAff_isOnCurve(Q0, Q1)) {

if (!ecAff_isOnCurve(Qx, Qy)) {
return false;
}

Expand All @@ -359,12 +363,11 @@ library FCL_Elliptic_ZZ {
uint256 scalar_v = mulmod(r, sInv, n);
uint256 x1;

x1 = ecZZ_mulmuladd_S_asm(Q0, Q1, scalar_u, scalar_v);
x1 = ecZZ_mulmuladd_S_asm(Qx, Qy, scalar_u, scalar_v);

assembly {
x1 := addmod(x1, sub(n, r), n)
}
//return true;
return x1 == 0;
}

Expand Down Expand Up @@ -410,7 +413,7 @@ library FCL_Elliptic_ZZ {
// Call the precompiled ModExp (0x05) https://www.evm.codes/precompiled#0x05
if iszero(
staticcall(
not(0), // amount of gas to send
gas(), // amount of gas to send
MODEXP_PRECOMPILE, // target
pointer, // argsOffset
0xc0, // argsSize (6 * 32 bytes)
Expand All @@ -428,12 +431,12 @@ library FCL_Elliptic_ZZ {

return result;
}

/**
* @dev Computation of uG+vQ using Strauss-Shamir's trick, G basepoint, Q public key
* Returns affine representation of point (normalized)
*
*/

function ecZZ_mulmuladd(
uint256 Q0,
uint256 Q1, //affine rep for input point Q
Expand Down Expand Up @@ -535,12 +538,10 @@ library FCL_Elliptic_ZZ {
T3 := mulmod(X, T2, p) // S = X1*V

T1 := mulmod(T1, T2, p) // W=UV
y2 := addmod(X, zz, p) //X+ZZ
let TT1 := addmod(X, sub(p, zz), p) //X-ZZ
y2 := mulmod(y2, TT1, p) //(X-ZZ)(X+ZZ)
T4 := mulmod(3, y2, p) //M
y2 := mulmod(addmod(X, zz, p), addmod(X, sub(p, zz), p), p) //(X-ZZ)(X+ZZ)
T4 := mulmod(3, y2, p) //M=3*(X-ZZ)(X+ZZ)

zzz := mulmod(TT1, zzz, p) //zzz3=W*zzz1
zzz := mulmod(T1, zzz, p) //zzz3=W*zzz1
zz := mulmod(T2, zz, p) //zz3=V*ZZ1, V free

X := addmod(mulmod(T4, T4, p), mulmod(minus_2, T3, p), p) //X3=M^2-2S
Expand Down Expand Up @@ -577,7 +578,7 @@ library FCL_Elliptic_ZZ {
mstore(add(T, 0xa0), p)

// Call the precompiled contract 0x05 = ModExp
if iszero(staticcall(not(0), 0x05, T, 0xc0, T, 0x20)) { revert(0, 0) }
if iszero(staticcall(gas(), 0x05, T, 0xc0, T, 0x20)) { revert(0, 0) }

Y := mulmod(Y, mload(T), p) //Y/zzz
zz := mulmod(zz, mload(T), p) //1/z
Expand Down

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