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56 lines
1.6 KiB
56 lines
1.6 KiB
12 years ago
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#ifndef _SECP256K1_ECDSA_
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#define _SECP256K1_ECDSA_
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namespace secp256k1 {
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bool ParsePubkey(GroupElemJac &elem, const unsigned char *pub, int size) {
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if (size == 33 && (pub[0] == 0x02 || pub[0] == 0x03)) {
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FieldElem x;
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x.SetBytes(pub+1);
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elem.SetCompressed(x, pub[0] == 0x03);
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} else if (size == 65 && (pub[0] == 0x04 || pub[0] == 0x06 || pub[0] == 0x07)) {
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FieldElem x,y;
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x.SetBytes(pub+1);
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y.SetBytes(pub+33);
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elem = GroupElem(x,y);
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if ((pub[0] == 0x06 || pub[0] == 0x07) && y.IsOdd() != (pub[0] == 0x07))
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return false;
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} else {
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return false;
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}
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return elem.IsValid();
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}
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class Signature {
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private:
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Number r,s;
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public:
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bool Verify(Context &ctx, const GroupElemJac &pubkey, const Number &message) {
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const GroupConstants &c = GetGroupConst();
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if (r.IsNeg() || s.IsNeg())
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return false;
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if (r.IsZero() || s.IsZero())
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return false;
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if (r.Compare(c.order) >= 0 || s.Compare(c.order) >= 0)
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return false;
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Context ct(ctx);
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Number sn(ct); sn.SetModInverse(ct, s, c.order);
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Number u1(ct); u1.SetModMul(ct, sn, message, c.order);
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Number u2(ct); u2.SetModMul(ct, sn, r, c.order);
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GroupElemJac pr; ECMult(ct, pr, pubkey, u2, u1);
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if (pr.IsInfinity())
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return false;
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FieldElem xr; pr.GetX(xr);
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unsigned char xrb[32]; xr.GetBytes(xrb);
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Number xrn(ct); xrn.SetBytes(xrb,32); xrn.SetMod(ct,xrn,c.order);
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return xrn.Compare(r) == 0;
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}
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};
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}
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#endif
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