From 7d9936e55cce653329864a2d60b296e68457089d Mon Sep 17 00:00:00 2001
From: Kevin Froman <beardog@firemail.cc>
Date: Sat, 5 May 2018 16:50:15 -0500
Subject: [PATCH] work on proof of work

---
 onionr/communicator.py | 31 +++++++++++++++++++++++++++++++
 onionr/core.py         |  1 -
 onionr/onionrcrypto.py | 12 ++++++++++--
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/onionr/communicator.py b/onionr/communicator.py
index 7bbfe87c..00f4d31c 100755
--- a/onionr/communicator.py
+++ b/onionr/communicator.py
@@ -561,6 +561,12 @@ class OnionrCommunicate:
                             blockMeta2 = {'type': ''}
                             pass
                         blockContent = blockContent[blockContent.rfind(b'}') + 1:]
+                        
+                        if not self.verifyPow(blockContent, blockMeta2):
+                            logger.warn(i + " has invalid or insufficient proof of work token, deleting")
+                            self._core.removeBlock(i)
+                            continue
+
                         try:
                             blockMetadata['sig']
                             blockMeta2['id']
@@ -656,6 +662,31 @@ class OnionrCommunicate:
                 peerTryCount += 1
 
         return retVal
+    
+    def verifyPow(self, blockContent, metadata):
+        '''
+            Verifies the proof of work associated with a block
+        '''
+        retData = False
+        try:
+            metadata['pow']
+            token = metadata['pow']
+        except KeyError:
+            return False
+        dataLen = len(blockContent)
+        expectedHash = self._crypto.blake2bHash(blockContent)
+        difficulty = 0
+        if token == expectedHash:
+            difficulty = math.floor(dataLen/1000000)
+
+            mainHash = '0000000000000000000000000000000000000000000000000000000000000000'#nacl.hash.blake2b(nacl.utils.random()).decode()
+            puzzle = mainHash[0:difficulty]
+
+            if token[0:difficulty] == puzzle:
+                logger.info('Validated block pow')
+                retData = True
+                
+        return retData
 
     def urlencode(self, data):
         '''
diff --git a/onionr/core.py b/onionr/core.py
index dae25bc3..74a703a4 100644
--- a/onionr/core.py
+++ b/onionr/core.py
@@ -638,7 +638,6 @@ class Core:
             if powToken != False:
                 break
             time.sleep(0.3)
-        
 
         try:
             data.decode()
diff --git a/onionr/onionrcrypto.py b/onionr/onionrcrypto.py
index 3a45eeda..d420cbd4 100644
--- a/onionr/onionrcrypto.py
+++ b/onionr/onionrcrypto.py
@@ -17,7 +17,7 @@
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 '''
-import nacl.signing, nacl.encoding, nacl.public, nacl.secret, os, binascii, base64, hashlib, logger
+import nacl.signing, nacl.encoding, nacl.public, nacl.hash, nacl.secret, os, binascii, base64, hashlib, logger
 
 class OnionrCrypto:
     def __init__(self, coreInstance):
@@ -209,4 +209,12 @@ class OnionrCrypto:
             hasher.update(pubkey + prev)
             prev = hasher.hexdigest()
         result = prev
-        return result
\ No newline at end of file
+        return result
+
+    def sha3Hash(self, data):
+        hasher = hashlib.sha3_256()
+        hasher.update(data)
+        return hasher.hexdigest()
+    
+    def blake2bHash(self, data):
+        return nacl.hash.blake2b(data)
\ No newline at end of file