Blackcoin Lore

src/pubkey.cpp

@@ -280,6 +280,55 @@ bool CExtPubKey::Derive(CExtPubKey &out, unsigned int nChild) const {
     return (!secp256k1_ecdsa_signature_normalize(secp256k1_context_verify, NULL, &sig));
 }
 
+int CompareBigEndian(const unsigned char *c1, size_t c1len, const unsigned char *c2, size_t c2len) {
+    while (c1len > c2len) {
+        if (*c1)
+            return 1;
+        c1++;
+        c1len--;
+    }
+    while (c2len > c1len) {
+        if (*c2)
+            return -1;
+        c2++;
+        c2len--;
+    }
+    while (c1len > 0) {
+        if (*c1 > *c2)
+            return 1;
+        if (*c2 > *c1)
+            return -1;
+        c1++;
+        c2++;
+        c1len--;
+    }
+    return 0;
+}
+
+const unsigned char vchZero[1] = {0};
+
+/** Order of secp256k1's generator minus 1. */
+const unsigned char vchMaxModOrder[32] = {
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,
+    0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,
+    0xBF,0xD2,0x5E,0x8C,0xD0,0x36,0x41,0x40
+};
+
+/** Half of the order of secp256k1's generator minus 1. */
+const unsigned char vchMaxModHalfOrder[32] = {
+    0x7F,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+    0x5D,0x57,0x6E,0x73,0x57,0xA4,0x50,0x1D,
+    0xDF,0xE9,0x2F,0x46,0x68,0x1B,0x20,0xA0
+};
+
+bool CPubKey::CheckSignatureElement(const unsigned char *vch, int len, bool half) {
+    return vch &&
+           CompareBigEndian(vch, len, vchZero, 0) > 0 &&
+           CompareBigEndian(vch, len, half ? vchMaxModHalfOrder : vchMaxModOrder, 32) <= 0;
+}
+
 /* static */ int ECCVerifyHandle::refcount = 0;
 
 ECCVerifyHandle::ECCVerifyHandle()