properly implement verification using keys that have been replaced.

the basic idea is replace txIndex key with a pair (username,height).
height = -1 for the most up-to-date key, otherwise height = last block where previous key was valid.
by checking maxHeight and iterating backwards we can easily find the key to validate data from any given block number.

TODO

@@ -7,6 +7,7 @@ pseudocode:
    getTxIndex( key = "userX" ) => block h contains this tx;
    while( h > max_h )
         getTxIndex( "userX_h" ) => block h contains the previous tx
+=> GetTransation: new parameter maxHeight done!
 
 - Until old public key is properly used, disable banning torrent peers due to bad piece hashes.
 note: torrent.cpp line 3286 (function piece_failed), iteration to ban peers is disabled (continue).

src/chainparams.cpp

@@ -46,20 +46,21 @@ public:
         //   vMerkleTree: 4a5e1e
         const char* pszTimestamp = "The Times 09/Jul/2013 Globo caught bribing Receita Federal employee to rob R$615M worth tax evasion documents.";
         CTransaction txNew;
-        txNew.message = CScript() << vector<unsigned char>((const unsigned char*)pszTimestamp, (const unsigned char*)pszTimestamp + strlen(pszTimestamp));
+        txNew.message = CScript() << string(pszTimestamp);
+        txNew.userName = CScript() << string("nobody");
         txNew.nNonce  = 0; // spamMessage is not required to show POW to ease "extranonce" support
         genesis.vtx.push_back(txNew);
         genesis.hashPrevBlock = 0;
         genesis.hashMerkleRoot = genesis.BuildMerkleTree();
         genesis.nVersion = 1;
         genesis.nHeight  = 0;
-        genesis.nTime    = 1373331180;
+        genesis.nTime    = 1383612321;
         //genesis.nBits    = 0x1d00ffff;
         genesis.nBits    = 0x1d7fffff;
-        genesis.nNonce   = 636561156;
+        genesis.nNonce   = 1353330432;
 
         hashGenesisBlock = genesis.GetHash();
-        assert(hashGenesisBlock == uint256("0x000000792bc5674af6fa5c006149d78c47265f7e03d2ca7f5a094b2475ef1328"));
+        assert(hashGenesisBlock == uint256("0000001d5eb70d639089eb9b31a4175aa906d6824aae78a9b450ab71de5e6e12"));
 
         vSeeds.push_back(CDNSSeedData("twister.net.co", "seed.twister.net.co"));
 

src/core.cpp

@@ -78,13 +78,22 @@ uint256 CTransaction::GetHash() const
     return SerializeHash(*this);
 }
 
+std::string CTransaction::GetUsername() const
+{
+    if(userName.IsSmallString()) {
+        return userName.ExtractSmallString();
+    }
+    assert(!"username not small string");
+    return std::string();
+}
+
 uint256 CTransaction::GetUsernameHash() const
 {
     if(userName.IsSmallString()) {
         return SerializeHash(userName.ExtractSmallString());
     }
     // [MF] TODO: remove this assert later, it will fail for spammessage.
-    //assert(!"username not small string");
+    assert(!"username not small string");
     return uint256();
 }
 

src/core.h

@@ -215,6 +215,7 @@ public:
     }
 
     uint256 GetHash() const;
+    std::string GetUsername() const;
     uint256 GetUsernameHash() const;
 
     bool IsSpamMessage() const

src/main.cpp

@@ -335,7 +335,7 @@ int CMerkleTx::SetMerkleBranch(const CBlock* pblock)
         CTransaction tx2;
         uint256 hashBlock2;
 
-        if( GetTransaction(GetUsernameHash(), tx2, hashBlock2) && hashBlock2 != uint256() ) {
+        if( GetTransaction(GetUsername(), tx2, hashBlock2) && hashBlock2 != uint256() ) {
             std::map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hashBlock2);
             if (mi != mapBlockIndex.end()) {
                 CBlockIndex *pindex = (*mi).second;
@@ -421,7 +421,7 @@ bool DoTxProofOfWork(CTransaction& tx)
 }
 
 // [MF] check tx consistency and pow, not duplicated id.
-bool CheckTransaction(const CTransaction& tx, CValidationState &state)
+bool CheckTransaction(const CTransaction& tx, CValidationState &state, int maxHeight)
 {
     // Basic checks that don't depend on any context
     if (tx.IsSpamMessage()) {
@@ -442,8 +442,7 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state)
             CPubKey pubkey;
             CTransaction txPubKey;
             uint256 hashBlock;
-            uint256 userhash = SerializeHash(spamUser);
-            if( !GetTransaction(userhash, txPubKey, hashBlock) )
+            if( !GetTransaction(spamUser, txPubKey, hashBlock, maxHeight) )
                 return state.DoS(100, error("CheckTransaction() : spam signed by unknown user"));
 
             std::vector< std::vector<unsigned char> > vData;
@@ -518,7 +517,8 @@ bool CTxMemPool::accept(CValidationState &state, CTransaction &tx, bool fLimitFr
 
     {
         // do we already have it?
-        if( pblocktree->HaveTxIndex(tx.GetUsernameHash()) &&
+        uint256 txid = SerializeHash(make_pair(tx.GetUsername(),-1));
+        if( pblocktree->HaveTxIndex(txid) &&
             // duplicate should be discarded but replacement is allowed.
             !verifyDuplicateOrReplacementTx(tx, false, true) ) {
             return false;
@@ -666,24 +666,21 @@ bool CWalletTx::AcceptWalletTransaction()
 
 
 // Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock
-bool GetTransaction(const uint256 &userhash, CTransaction &txOut, uint256 &hashBlock, bool fAllowSlow)
+bool GetTransaction(const std::string &username, CTransaction &txOut, uint256 &hashBlock, int maxHeight)
 {
+    if( maxHeight < 0 )
+        maxHeight = nBestHeight;
     {
         LOCK(cs_main);
-        {
-            /* [MF] don't look in mempool anymore - userhash must be written to some block.
-            LOCK(mempool.cs);
-            if (mempool.exists(userhash)) // and btw mempool is not indexed by userhash anymore!
-            {
-                txOut = mempool.lookup(userhash);
-                return true;
-            }
-            */
-        }
 
-        if (fTxIndex) {
+        assert(fTxIndex);
+
+        int height = -1;
+        do {
+            uint256 txid = SerializeHash(make_pair(username,height));
+
             CDiskTxPos postx;
-            if (pblocktree->ReadTxIndex(userhash, postx)) {
+            if (pblocktree->ReadTxIndex(txid, postx)) {
                 CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
                 CBlockHeader header;
                 try {
@@ -694,21 +691,29 @@ bool GetTransaction(const uint256 &userhash, CTransaction &txOut, uint256 &hashB
                     return error("%s() : deserialize or I/O error", __PRETTY_FUNCTION__);
                 }
                 hashBlock = header.GetHash();
-                if (txOut.GetUsernameHash() != userhash)
+                if (txOut.GetUsername() != username)
                     return error("%s() : txid mismatch", __PRETTY_FUNCTION__);
-                return true;
+                if (header.nHeight > maxHeight) {
+                    printf("GetTransaction: %s height: %d blkHeight: %d maxHeight: %d\n",
+                           username.c_str(), height, header.nHeight, maxHeight);
+                    height = header.nHeight-1;
+                } else {
+                    return true;
+                }
+            } else {
+                break;
             }
-        }
+        } while( height > 0 && height <= maxHeight );
     }
 
     return false;
 }
 
-bool verifyDuplicateOrReplacementTx(CTransaction &tx, bool checkDuplicate, bool checkReplacement)
+bool verifyDuplicateOrReplacementTx(CTransaction &tx, bool checkDuplicate, bool checkReplacement, int maxHeight)
 {
     CTransaction oldTx;
     uint256 hashBlock;
-    if( GetTransaction( tx.GetUsernameHash(), oldTx, hashBlock) ) {
+    if( GetTransaction( tx.GetUsername(), oldTx, hashBlock, maxHeight) ) {
         if( checkDuplicate && oldTx.GetHash() == tx.GetHash() ) {
             return true;
         }
@@ -1072,8 +1077,20 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
     for (int i = block.vtx.size() - 1; i >= 1; i--) {
         const CTransaction &tx = block.vtx[i];
 
-        if( !fJustCheck )
-          pblocktree->EraseTxIndex(tx.GetUsernameHash());
+        if( !fJustCheck ) {
+          uint256 oldTxid = SerializeHash(make_pair(tx.GetUsername(),block.nHeight-1));
+          CDiskTxPos oldPos;
+          if( pblocktree->ReadTxIndex(oldTxid, oldPos) ) {
+              printf("DisconnectBlock: restoring old txid user: %s height: %d\n",
+                     tx.GetUsername().c_str(), block.nHeight);
+
+              uint256 txid = SerializeHash(make_pair(tx.GetUsername(),-1));
+              std::vector<std::pair<uint256, CDiskTxPos> > vPos;
+              vPos.push_back(std::make_pair(txid, oldPos));
+              if (!pblocktree->WriteTxIndex(vPos))
+                  return state.Abort(_("Failed to write transaction index"));
+          }
+        }
     }
 
     // move best block pointer to prevout block
@@ -1129,14 +1146,15 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
     for (unsigned int i = 1; i < block.vtx.size(); i++) {
         CTransaction &tx = block.vtx[i];
 
-        if( pblocktree->HaveTxIndex(block.vtx[i].GetUsernameHash()) ) {
+        uint256 txid = SerializeHash(make_pair(block.vtx[i].GetUsername(),-1));
+        if( pblocktree->HaveTxIndex(txid) ) {
             /* We have index for this username, which is not allowed, except:
              * 1) same transaction. this shouldn't happen but it does if twisterd terminates badly.
              *    explanation: TxIndex seems to get out-of-sync with block chain, so it may try to
              *    reconnect blocks which transactions are already written to the tx index.
              * 2) possibly a key replacement. check if new key is signed by the old one.
              */
-            if( !verifyDuplicateOrReplacementTx(tx, true, true) ) {
+            if( !verifyDuplicateOrReplacementTx(tx, true, true, block.nHeight) ) {
                 // not the same, not replacement => error!
                 return state.DoS(100, error("ConnectBlock() : tried to overwrite transaction"));
             }
@@ -1156,7 +1174,16 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
         CTxUndo txundo;
         if (!tx.IsSpamMessage()) {
             blockundo.vtxundo.push_back(txundo);
-            vPos.push_back(std::make_pair(tx.GetUsernameHash(), pos));
+            uint256 txid = SerializeHash(make_pair(tx.GetUsername(),-1));
+            vPos.push_back(std::make_pair(txid, pos));
+
+            CDiskTxPos oldPos;
+            if( pblocktree->ReadTxIndex(txid, oldPos) && pos != oldPos ) {
+                printf("ConnectBlock: save old txid user: %s height: %d\n",
+                       tx.GetUsername().c_str(), block.nHeight);
+                uint256 oldTxid = SerializeHash(make_pair(tx.GetUsername(),block.nHeight-1));
+                vPos.push_back(std::make_pair(oldTxid, oldPos));
+            }
         }
         pos.nTxOffset += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
     }
@@ -1189,10 +1216,9 @@ bool ConnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, C
             return state.Abort(_("Failed to write block index"));
     }
 
-    if (fTxIndex) {
-        if (!pblocktree->WriteTxIndex(vPos))
-            return state.Abort(_("Failed to write transaction index"));
-    }
+    assert(fTxIndex);
+    if (!pblocktree->WriteTxIndex(vPos))
+        return state.Abort(_("Failed to write transaction index"));
 
     // add this block to the view's block chain
     assert(view.SetBestBlock(pindex));
@@ -1548,7 +1574,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
 
     // Check transactions (consistency, not duplicated id)
     BOOST_FOREACH(const CTransaction& tx, block.vtx)
-        if (!CheckTransaction(tx, state))
+        if (!CheckTransaction(tx, state, block.nHeight))
             return error("CheckBlock() : CheckTransaction failed");
 
     // Build the merkle tree already. We need it anyway later, and it makes the
@@ -2035,7 +2061,7 @@ bool static LoadBlockIndexDB()
     bool readTxIndex;
     pblocktree->ReadFlag("txindex", readTxIndex);
     printf("LoadBlockIndexDB(): transaction index %s\n", readTxIndex ? "enabled" : "disabled");
-    //assert( readTxIndex ); // always true in twister
+    assert( readTxIndex ); // always true in twister
 
     // Load hashBestChain pointer to end of best chain
     pindexBest = pcoinsTip->GetBestBlock();
@@ -3572,7 +3598,7 @@ static bool CreateSpamMsgTx(CTransaction &txNew, std::vector<unsigned char> &sal
 
     CValidationState state;
     bool ret = CheckTransaction(txNew, state);
-    printf("CheckTransaction returned %d\n", ret );
+    printf("CreateSpamMsgTx: CheckTransaction returned %d\n", ret );
 
     return true;
 }
@@ -3629,7 +3655,8 @@ CBlockTemplate* CreateNewBlock(std::vector<unsigned char> &salt)
                 continue;
 
             // This should never happen; all transactions in the memory are new
-            if( pblocktree->HaveTxIndex(tx.GetUsernameHash()) ) {
+            uint256 txid = SerializeHash(make_pair(tx.GetUsername(),-1));
+            if( pblocktree->HaveTxIndex(txid) ) {
                 if( !verifyDuplicateOrReplacementTx(tx, false, true) ) {
                     printf("ERROR: mempool transaction already exists\n");
                     if (fDebug) assert("mempool transaction already exists" == 0);

src/main.h

@@ -182,9 +182,9 @@ bool IsInitialBlockDownload();
 /** Format a string that describes several potential problems detected by the core */
 std::string GetWarnings(std::string strFor);
 /** Retrieve a transaction (from memory pool, or from disk, if possible) */
-bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock, bool fAllowSlow = false);
+bool GetTransaction(const std::string &username, CTransaction &tx, uint256 &hashBlock, int maxHeight = -1);
 /** Verify duplicate or replacement transactions */
-bool verifyDuplicateOrReplacementTx(CTransaction &tx, bool checkDuplicate, bool checkReplacement);
+bool verifyDuplicateOrReplacementTx(CTransaction &tx, bool checkDuplicate, bool checkReplacement, int maxHeight = -1);
 /** Connect/disconnect blocks until pindexNew is the new tip of the active block chain */
 bool SetBestChain(CValidationState &state, CBlockIndex* pindexNew);
 /** Find the best known block, and make it the tip of the block chain */
@@ -275,7 +275,7 @@ bool CheckUsername(const std::string &userName, CValidationState &state);
 bool DoTxProofOfWork(CTransaction& tx);
 
 // Context-independent validity checks
-bool CheckTransaction(const CTransaction& tx, CValidationState& state);
+bool CheckTransaction(const CTransaction& tx, CValidationState& state, int maxHeight = -1);
 
 /** Check for standard transaction types
     @return True if all outputs (scriptPubKeys) use only standard transaction forms

src/rpcdump.cpp

@@ -93,8 +93,7 @@ Value importprivkey(const Array& params, bool fHelp)
     if( !fAllowNewUser ) {
         CTransaction txOut;
         uint256 hashBlock;
-        uint256 userhash = SerializeHash(strUsername);
-        if( !GetTransaction(userhash, txOut, hashBlock) ) {
+        if( !GetTransaction(strUsername, txOut, hashBlock) ) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "User must exist (or allow_new_user flag must be set)");
         }
     }

src/rpcrawtransaction.cpp

@@ -122,7 +122,7 @@ Value getrawtransaction(const Array& params, bool fHelp)
             "with information about transaction.");
 
     //uint256 hash = ParseHashV(params[0], "parameter 1");
-    uint256 hash = SerializeHash(params[0].get_str());
+    std::string username = params[0].get_str();
 
     bool fVerbose = false;
     if (params.size() > 1)
@@ -130,7 +130,7 @@ Value getrawtransaction(const Array& params, bool fHelp)
 
     CTransaction tx;
     uint256 hashBlock = 0;
-    if (!GetTransaction(hash, tx, hashBlock, true))
+    if (!GetTransaction(username, tx, hashBlock))
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available about transaction");
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
@@ -227,7 +227,7 @@ Value sendrawtransaction(const Array& params, bool fHelp)
     bool fHave = false;
     uint256 hashBlock;
     CTransaction tx2;
-    fHave = GetTransaction(tx.GetUsernameHash(), tx2, hashBlock);
+    fHave = GetTransaction(tx.GetUsername(), tx2, hashBlock);
 
     // treat replacement as !fHave
     if( fHave && verifyDuplicateOrReplacementTx(tx, false, true) ) {
@@ -283,8 +283,7 @@ Value sendnewusertransaction(const Array& params, bool fHelp)
   // [MF] prevent redoing POW and resending an existing transaction
   CTransaction txOut;
   uint256 hashBlock;
-  uint256 userhash = SerializeHash(strUsername);
-  bool userInTxIndex = GetTransaction(userhash, txOut, hashBlock);
+  bool userInTxIndex = GetTransaction(strUsername, txOut, hashBlock);
   if( !replaceKey && userInTxIndex )
       throw JSONRPCError(RPC_WALLET_INVALID_ACCOUNT_NAME, "Error: this username exists in tx database");
   if( replaceKey && !userInTxIndex )

src/rpcwallet.cpp

@@ -114,12 +114,9 @@ Value createwalletuser(const Array& params, bool fHelp)
     if( !keyInWallet && replaceKey )
       throw JSONRPCError(RPC_WALLET_INVALID_ACCOUNT_NAME, "Error: replacekey given but old key not in wallet");
 
-    uint256 userhash = SerializeHash(strUsername);
-    printf("createwalletuser: usernamehash(%s) = %s\n", strUsername.c_str(), userhash.GetHex().c_str());
-
     CTransaction txOut;
     uint256 hashBlock;
-    if( GetTransaction(userhash, txOut, hashBlock) && !replaceKey )
+    if( GetTransaction(strUsername, txOut, hashBlock) && !replaceKey )
         throw JSONRPCError(RPC_WALLET_INVALID_ACCOUNT_NAME, "Error: this username exists in tx database");
 
     if( replaceKey && !pwalletMain->MoveKeyForReplacement(strUsername) )
@@ -259,8 +256,7 @@ Value verifymessage(const Array& params, bool fHelp)
     if( !pubkey.IsValid() ) {
       CTransaction txOut;
       uint256 hashBlock;
-      uint256 userhash = SerializeHash(strUsername);
-      if( !GetTransaction(userhash, txOut, hashBlock) )
+      if( !GetTransaction(strUsername, txOut, hashBlock) )
           throw JSONRPCError(RPC_WALLET_INVALID_ACCOUNT_NAME, "Error: this username does not exist in tx database");
 
       std::vector< std::vector<unsigned char> > vData;

src/twister.cpp

@@ -404,8 +404,7 @@ void ThreadSessionAlerts()
                                 // check if user exists
                                 CTransaction txOut;
                                 uint256 hashBlock;
-                                uint256 userhash = SerializeHash(n->string());
-                                if( !GetTransaction(userhash, txOut, hashBlock) ) {
+                                if( !GetTransaction(n->string(), txOut, hashBlock) ) {
                                     printf("Special Resource but username is unknown - ignoring\n");
                                 } else {
                                         // now we do our own search to make sure we are really close to this target
@@ -621,8 +620,7 @@ bool getUserPubKey(std::string const &strUsername, CPubKey &pubkey)
     if( !pubkey.IsValid() ) {
       CTransaction txOut;
       uint256 hashBlock;
-      uint256 userhash = SerializeHash(strUsername);
-      if( !GetTransaction(userhash, txOut, hashBlock) ) {
+      if( !GetTransaction(strUsername, txOut, hashBlock) ) {
           //printf("getUserPubKey: user unknown '%s'\n", strUsername.c_str());
           return false;
       }
@@ -807,8 +805,7 @@ bool validatePostNumberForUser(std::string const &username, int k)
 {
     CTransaction txOut;
     uint256 hashBlock;
-    uint256 userhash = SerializeHash(username);
-    if( !GetTransaction(userhash, txOut, hashBlock) ) {
+    if( !GetTransaction(username, txOut, hashBlock) ) {
         printf("validatePostNumberForUser: username is unknown\n");
         return false;
     }
@@ -827,8 +824,7 @@ bool usernameExists(std::string const &username)
 {
     CTransaction txOut;
     uint256 hashBlock;
-    uint256 userhash = SerializeHash(username);
-    return GetTransaction(userhash, txOut, hashBlock);
+    return GetTransaction(username, txOut, hashBlock);
 }