Package: blockcerts-merkletools
blockcerts-pymerkletoolsThis is a Python port ofsolidity-pymerkletools, which supports Web3's solidity keccak hashing function.  This fork supports updated dependencies per Blockcerts project requirements.Tools for creating Merkle trees, generating merkle proofs, and verification of merkle proofs.Installationpip install blockcerts-merkletoolsCreate MerkleTools Objectimportblockcerts_merkletoolsmt=MerkleTools()# default hash algorithm is Web3.solidity_keccakMethodsadd_leaf(value, do_hash)Adds a value as a leaf or a list of leafs to the tree. The value must be a hex string.mt.add_leaf("0x4b39F7b0624b9dB86AD293686bc38B903142dbBc")mt.add_leaf("0x71b4a2d9B91726bdb5849D928967A1654D7F3de7")get_leaf_count()Returns the number of leaves that are currently added to the tree.leaf_count=mt.get_leaf_count();get_leaf(index)Returns the value of the leaf at the given index as a hex string.leaf_value=mt.get_leaf(1)reset_tree()Removes all the leaves from the tree, prepararing to to begin creating a new tree.mt.reset_tree()make_tree()Generates the merkle tree using the leaves that have been added.mt.make_tree();is_ready.is_readyis a boolean property indicating if the tree is built and ready to supply its root and proofs. Theis_readystate isTrueonly after calling 'make_tree()'.  Adding leaves or resetting the tree will change the ready state to False.is_ready=mt.is_readyget_merkle_root()Returns the merkle root of the tree as a hex string. If the tree is not ready,Noneis returned.root_value=mt.get_merkle_root();get_proof(index)Returns the proof as an array of hash objects for the leaf at the given index. If the tree is not ready or no leaf exists at the given index, null is returned.proof=mt.get_proof(1)The proof array contains a set of merkle sibling objects. Each object contains the sibling hash, with the key value of either right or left. The right or left value tells you where that sibling was in relation to the current hash being evaluated. This information is needed for proof validation, as explained in the following section.validate_proof(proof, target_hash, merkle_root)Returns a boolean indicating whether or not the proof is valid and correctly connects thetarget_hashto themerkle_root.proofis a proof array as supplied by theget_proofmethod. Thetarget_hashandmerkle_rootparameters must be a hex strings.proof=[{right:'09096dbc49b7909917e13b795ebf289ace50b870440f10424af8845fb7761ea5'},{right:'ed2456914e48c1e17b7bd922177291ef8b7f553edf1b1f66b6fc1a076524b22f'},{left:'eac53dde9661daf47a428efea28c81a021c06d64f98eeabbdcff442d992153a8'},]target_hash='36e0fd847d927d68475f32a94efff30812ee3ce87c7752973f4dd7476aa2e97e'merkle_root='b8b1f39aa2e3fc2dde37f3df04e829f514fb98369b522bfb35c663befa896766'is_valid=mt.validate_proof(proof,targetHash,merkleRoot)The proof process uses all the proof objects in the array to attempt to prove a relationship between thetarget_hashand themerkle_rootvalues. The steps to validate a proof are:Concatenatetarget_hashand the first hash in the proof array. The right or left designation specifies which side of the concatenation that the proof hash value should be on.Hash the resulting value.Concatenate the resulting hash with the next hash in the proof array, using the same left and right rules.Hash that value and continue the process until you’ve gone through each item in the proof array.The final hash value should equal themerkle_rootvalue if the proof is valid, otherwise the proof is invalid.Common UsageCreating a tree and generating the proofsmt=MerkleTools()mt.add_leaf("tierion",True)mt.add_leaf(["bitcoin","blockchain"],True)mt.make_tree()print"root:",mt.get_merkle_root()# root: '765f15d171871b00034ee55e48ffdf76afbc44ed0bcff5c82f31351d333c2ed1'printmt.get_proof(1)# [{left: '2da7240f6c88536be72abe9f04e454c6478ee29709fc3729ddfb942f804fbf08'},#  {right: 'ef7797e13d3a75526946a3bcf00daec9fc9c9c4d51ddc7cc5df888f74dd434d1'}]printmt.validate_proof(mt.get_proof(1),mt.get_leaf(1),mt.get_merkle_root())# TrueNotesAbout tree generationInternally, leaves are stored asbytearray. When the tree is built, it is generated by hashing together thebytearrayvalues.Lonely leaf nodes are promoted to the next level up, as depicted below.ROOT=Hash(H+E)
                  /        \
                 /          \
          H=Hash(F+G)        E
          /       \           \
         /         \           \
  F=Hash(A+B)    G=Hash(C+D)    E
   /     \        /     \        \
  /       \      /       \        \

 A         B    C         D        E