From e3f741f1d4263ba87ae41149039ce4838fd99089 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Tue, 12 Mar 2013 00:39:29 +0100
Subject: [PATCH] validation bugfixes: validates main bitcoin chain

---
 ecdsa.h   | 17 +++++++++++++----
 field.h   |  6 +++---
 group.h   |  4 ++--
 num_gmp.h |  8 ++++----
 4 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/ecdsa.h b/ecdsa.h
index 8588ad0d69..2fd4dfd5b1 100644
--- a/ecdsa.h
+++ b/ecdsa.h
@@ -30,11 +30,11 @@ public:
 
     bool Parse(const unsigned char *sig, int size) {
         if (sig[0] != 0x30) return false;
-        if (sig[1] != size-2) return false;
         int lenr = sig[3];
-        if (4+lenr >= size) return false;
+        if (5+lenr >= size) return false;
         int lens = sig[lenr+5];
-        if (lenr+lens+6 != size) return false;
+        if (sig[1] != lenr+lens+4) return false;
+        if (lenr+lens+6 > size) return false;
         if (sig[2] != 0x02) return false;
         if (lenr == 0) return false;
         if (sig[lenr+4] != 0x02) return false;
@@ -80,6 +80,10 @@ public:
         r = rin;
         s = sin;
     }
+
+    std::string ToString() const {
+        return "(" + r.ToString() + "," + s.ToString() + ")";
+    }
 };
 
 int VerifyECDSA(const unsigned char *msg, int msglen, const unsigned char *sig, int siglen, const unsigned char *pubkey, int pubkeylen) {
@@ -90,8 +94,13 @@ int VerifyECDSA(const unsigned char *msg, int msglen, const unsigned char *sig,
     m.SetBytes(msg, msglen);
     if (!ParsePubKey(q, pubkey, pubkeylen))
         return -1;
-    if (!s.Parse(sig, siglen))
+    if (!s.Parse(sig, siglen)) {
+        fprintf(stderr, "Can't parse signature: ");
+        for (int i=0; i<siglen; i++) fprintf(stderr,"%02x", sig[i]);
+        fprintf(stderr, "\n");
         return -2;
+    }
+//    fprintf(stderr, "Verifying ECDSA: msg=%s pubkey=%s sig=%s\n", m.ToString().c_str(), q.ToString().c_str(), s.ToString().c_str());
     if (!s.Verify(ctx, q, m))
         return 0;
     return 1;
diff --git a/field.h b/field.h
index 1d01957351..1aa6d1e9c6 100644
--- a/field.h
+++ b/field.h
@@ -308,7 +308,7 @@ public:
     }
 
     /** Set this to be the (modular) inverse of another FieldElem. Magnitude=1 */
-    void SetInverse(Context &ctx, const FieldElem &a);
+    void SetInverse(Context &ctx, FieldElem &a);
 
     std::string ToString() {
         unsigned char tmp[32];
@@ -368,7 +368,7 @@ const FieldConstants &GetFieldConst() {
     return field_const;
 }
 
-void FieldElem::SetInverse(Context &ctx, const FieldElem &a) {
+void FieldElem::SetInverse(Context &ctx, FieldElem &a) {
 #if 0
     // calculate a^p, with p={45,63,1019,1023}
     FieldElem a2; a2.SetSquare(a);
@@ -402,7 +402,7 @@ void FieldElem::SetInverse(Context &ctx, const FieldElem &a) {
     SetMult(x,a45);
 #else
     unsigned char b[32];
-    GetBytes(b);
+    a.GetBytes(b);
     {
         const Number &p = GetFieldConst().field_p;
         Context ct(ctx);
diff --git a/group.h b/group.h
index 2032467ed0..8809adca28 100644
--- a/group.h
+++ b/group.h
@@ -39,11 +39,11 @@ public:
         y.SetNeg(y, 1);
     }
 
-    void GetX(FieldElem &xout) const {
+    void GetX(Context &ctx, FieldElem &xout) {
         xout = x;
     }
 
-    void GetY(FieldElem &yout) const {
+    void GetY(Context &ctx, FieldElem &yout) {
         yout = y;
     }
 
diff --git a/num_gmp.h b/num_gmp.h
index 9b0631d079..a5b1062b49 100644
--- a/num_gmp.h
+++ b/num_gmp.h
@@ -70,7 +70,7 @@ public:
         memset(bin,0,len);
         size_t count = 0;
         mpz_export(bin + len - size, &count, 1, 1, 1, 0, bn);
-        assert(size == count);
+        assert(count == 0 || size == count);
     }
     void SetInt(int x) {
         mpz_set_si(bn, x);
@@ -80,7 +80,7 @@ public:
     }
     void SetModMul(Context &ctx, const Number &a, const Number &b, const Number &m) {
         mpz_mul(bn, a.bn, b.bn);
-        mpz_mod(bn, a.bn, m.bn);
+        mpz_mod(bn, bn, m.bn);
     }
     void SetAdd(Context &ctx, const Number &a1, const Number &a2) {
         mpz_add(bn, a1.bn, a2.bn);
@@ -144,8 +144,8 @@ public:
         mpz_fdiv_q_2exp(high.bn, bn, bits);
     }
 
-    std::string ToString() {
-        char *str = (char*)malloc((GetBits() + 7)/8 + 2);
+    std::string ToString() const {
+        char *str = (char*)malloc(mpz_sizeinbase(bn,16) + 2);
         mpz_get_str(str, 16, bn);
         std::string ret(str);
         free(str);