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https://github.com/3b1b/manim.git
synced 2025-09-01 00:48:45 +00:00
Up to double spending attack in crypto
This commit is contained in:
Grant Sanderson
parent
fb408ab80d
commit
9edccb116e
1 changed files with 387 additions and 12 deletions
399
crypto.py
399
crypto.py
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@ -3520,18 +3520,393 @@ class TwoBlockChains(DistributedBlockChainScene):
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self.randy = randy
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return VGroup(randy)
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class ReplaceCentralAuthorityWithWork(Scene):
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def construct(self):
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trust, central = words = TextMobject("Trust", "central authority")
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words.scale(1.5)
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cross = Cross(central)
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work = TextMobject("computational work")
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work.scale(1.5)
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work.move_to(central, LEFT)
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work.highlight(YELLOW)
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self.play(Write(words))
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self.play(ShowCreation(cross))
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central.add(cross)
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self.play(
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central.shift, DOWN,
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Write(work)
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)
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self.dither()
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class AskAboutTrustingWork(TeacherStudentsScene):
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def construct(self):
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mode = "raise_left_hand"
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self.student_says(
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"Is trusting work \\\\ really enough?",
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target_mode = mode,
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)
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self.change_student_modes("confused", mode, "erm")
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self.dither(3)
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class DoubleSpendingAttack(DistributedBlockChainScene):
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CONFIG = {
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"fraud_block_height" : 3,
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}
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def construct(self):
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self.initialize_characters()
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self.show_fraudulent_block()
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self.send_to_bob()
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self.dont_send_to_rest_of_network()
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def initialize_characters(self):
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network = self.get_large_network()
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network.scale(0.7)
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block_chains = self.get_distributed_ledgers()
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self.add(network, block_chains)
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self.play(self.alice.change, "conniving")
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self.dither()
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def show_fraudulent_block(self):
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block = self.get_fraud_block()
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block.next_to(self.alice, LEFT, LARGE_BUFF)
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block.remove(block.content)
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self.play(
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ShowCreation(block),
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Write(block.content),
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self.alice.change, "raise_left_hand"
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)
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block.add(block.content)
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self.dither()
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self.block = block
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def send_to_bob(self):
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block = self.block.copy()
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block.generate_target()
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block.target.replace(
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self.bob.block_chain.blocks[-1],
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stretch = True
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)
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arrow = self.bob.block_chain.arrows[-1].copy()
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VGroup(arrow, block.target).next_to(
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self.bob.block_chain.blocks[-1], RIGHT, buff = 0
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)
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self.play(
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MoveToTarget(block),
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self.alice.change, "happy"
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)
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self.play(ShowCreation(arrow))
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self.dither()
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def dont_send_to_rest_of_network(self):
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bubble = ThoughtBubble()
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words = TextMobject("Alice", "never \\\\ paid", "Bob")
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for name in "Alice", "Bob":
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words.highlight_by_tex(name, self.get_color_from_name(name))
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bubble.add_content(words)
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bubble.resize_to_content()
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bubble.add(*bubble.content)
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bubble.move_to(self.you.get_corner(UP+RIGHT), DOWN+LEFT)
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self.play(
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self.charlie.change, "shruggie",
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self.you.change, "shruggie",
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)
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self.play(LaggedStart(FadeIn, bubble))
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self.play(self.bob.change, "confused", words)
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self.dither(2)
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###
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def get_fraud_block(self):
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block = self.get_block()
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block.scale_to_fit_height(self.fraud_block_height)
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content = VGroup()
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tuples = [
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("Prev hash", UP, BLUE),
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("Proof of work", DOWN, GREEN),
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]
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for word, vect, color in tuples:
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mob = TextMobject(word)
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mob.highlight(color)
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mob.scale_to_fit_height(0.07*block.get_height())
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mob.next_to(
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block.get_edge_center(vect), -vect,
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buff = 0.06*block.get_height()
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)
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content.add(mob)
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attr = word.lower().replace(" ", "_")
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setattr(block, attr, mob)
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payment = TextMobject("Alice", "pays", "Bob", "100 LD")
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for name in "Alice", "Bob":
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payment.highlight_by_tex(name, self.get_color_from_name(name))
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payment.highlight_by_tex("LD", YELLOW)
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payments = VGroup(
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TexMobject("\\vdots"),
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payment,
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TexMobject("\\vdots")
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)
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payments.arrange_submobjects(DOWN)
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payments.scale_to_fit_width(0.9*block.get_width())
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payments.move_to(block)
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content.add(payments)
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block.content = content
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block.add(content)
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return block
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class AliceRacesOtherMiners(DoubleSpendingAttack):
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CONFIG = {
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"n_frames_per_pow" : 3,
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"fraud_block_height" : 2,
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"n_miners" : 3,
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"n_proof_of_work_digits" : 11,
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"proof_of_work_update_counter" : 0,
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}
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def construct(self):
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self.initialize_characters()
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self.find_proof_of_work()
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self.receive_broadcast_from_other_miners()
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self.race_between_alice_and_miners()
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def initialize_characters(self):
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alice = self.alice
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bob = self.bob
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alice_l = VGroup(alice, alice.label)
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bob_l = VGroup(bob, bob.label)
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bob_l.move_to(ORIGIN)
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alice_l.to_corner(UP+LEFT)
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alice_l.shift(DOWN)
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self.add(bob_l, alice_l)
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chain = self.get_block_chain()
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chain.next_to(bob, UP)
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self.block_chain = chain
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self.add(chain)
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fraud_block = self.get_fraud_block()
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fraud_block.next_to(alice, RIGHT)
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fraud_block.to_edge(UP)
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proof_of_work = self.get_rand_int_mob()
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proof_of_work.replace(fraud_block.proof_of_work, dim_to_match = 1)
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fraud_block.content.remove(fraud_block.proof_of_work)
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fraud_block.content.add(proof_of_work)
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fraud_block.proof_of_work = proof_of_work
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self.fraud_block = fraud_block
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self.add(fraud_block)
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miners = VGroup(*[
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PiCreature(color = GREY)
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for x in range(self.n_miners)
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])
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miners.scale_to_fit_height(alice.get_height())
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miners.arrange_submobjects(RIGHT, buff = LARGE_BUFF)
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miners.to_edge(DOWN+LEFT)
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miners.shift(0.5*UP)
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miners_word = TextMobject("Miners")
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miners_word.next_to(miners, DOWN)
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self.miners = miners
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self.add(miners_word, miners)
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miner_blocks = VGroup()
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self.proofs_of_work = VGroup()
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self.add_foreground_mobject(self.proofs_of_work)
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for miner in miners:
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block = self.get_block()
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block.scale_to_fit_width(1.5*miner.get_width())
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block.next_to(miner, UP)
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transactions = self.get_block_filler(block)
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block.add(transactions)
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proof_of_work = self.get_rand_int_mob()
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prev_hash = TextMobject("Prev hash").highlight(BLUE)
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for mob, vect in (proof_of_work, DOWN), (prev_hash, UP):
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mob.scale_to_fit_height(0.1*block.get_height())
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mob.next_to(
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block.get_edge_center(vect), -vect,
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buff = 0.05*block.get_height()
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)
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block.add(mob)
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block.proof_of_work = proof_of_work
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block.prev_hash = prev_hash
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self.proofs_of_work.add(proof_of_work)
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miner.block = block
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miner_blocks.add(block)
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self.add(miner_blocks)
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def find_proof_of_work(self):
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fraud_block = self.fraud_block
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chain = self.block_chain
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self.proofs_of_work.add(self.fraud_block.proof_of_work)
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self.dither(3)
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self.proofs_of_work.remove(self.fraud_block.proof_of_work)
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fraud_block.proof_of_work.highlight(GREEN)
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self.play(
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Indicate(fraud_block.proof_of_work),
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self.alice.change, "hooray"
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)
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self.dither()
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block = fraud_block.copy()
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block.generate_target()
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block.target.replace(chain.blocks[-1], stretch = True)
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arrow = chain.arrows[-1].copy()
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VGroup(arrow, block.target).next_to(
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chain.blocks[-1], RIGHT, buff = 0
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)
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self.remove(fraud_block)
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self.clean_fraud_block_content()
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self.fraud_fork_head = block
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self.fraud_fork_arrow = arrow
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self.play(MoveToTarget(block))
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self.play(ShowCreation(arrow))
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self.play(self.alice.change, "happy")
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self.dither()
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def receive_broadcast_from_other_miners(self):
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winner = self.miners[-1]
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proof_of_work = winner.block.proof_of_work
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self.proofs_of_work.remove(proof_of_work)
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proof_of_work.highlight(GREEN)
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self.play(
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Indicate(proof_of_work),
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winner.change, "hooray"
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)
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block = winner.block.copy()
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proof_of_work.highlight(WHITE)
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self.remove(winner.block)
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ff_head = self.fraud_fork_head
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ff_arrow = self.fraud_fork_arrow
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arrow = ff_arrow.copy()
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movers = [ff_head, ff_arrow, block, arrow]
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for mover in movers:
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mover.generate_target()
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block.target.replace(ff_head, stretch = True)
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dist = 0.5*ff_head.get_height() + MED_SMALL_BUFF
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block.target.shift(dist*DOWN)
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ff_head.target.shift(dist*UP)
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arrow.target[1].shift(dist*DOWN)
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arrow.target.points[-2:] += dist*DOWN
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ff_arrow.target[1].shift(dist*UP)
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ff_arrow.target.points[-2:] += dist*UP
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self.revert_to_original_skipping_status()
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self.play(
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Broadcast(block),
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*[
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MoveToTarget(
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mover, run_time = 3,
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rate_func = squish_rate_func(smooth, 0.3, 0.8)
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)
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for mover in movers
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]
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)
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self.play(
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FadeIn(winner.block),
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winner.change_mode, "plain",
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self.alice.change, "sassy",
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)
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self.proofs_of_work.add(winner.block.proof_of_work)
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self.dither(2)
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self.play(
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self.alice.change, "pondering",
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FadeIn(self.fraud_block)
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)
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self.proofs_of_work.add(self.fraud_block.proof_of_work)
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self.valid_fork_head = block
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def race_between_alice_and_miners(self):
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last_fraud_block = self.fraud_fork_head
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last_valid_block = self.valid_fork_head
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chain = self.block_chain
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winners = [
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"Alice", "Alice",
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"Miners", "Miners", "Miners",
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"Alice", "Miners", "Miners", "Miners",
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"Alice", "Miners", "Miners"
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]
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for winner in winners:
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self.dither(2)
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if winner == "Alice":
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block = self.fraud_block
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prev_block = last_fraud_block
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else:
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block = random.choice(self.miners).block
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prev_block = last_valid_block
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block_copy = block.deepcopy()
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block_copy.proof_of_work.highlight(GREEN)
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block_copy.generate_target()
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block_copy.target.replace(chain.blocks[1], stretch = True)
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arrow = chain.arrows[0].copy()
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VGroup(arrow, block_copy.target).next_to(
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prev_block, RIGHT, buff = 0
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)
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anims = [
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MoveToTarget(block_copy, run_time = 2),
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ShowCreation(
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arrow,
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run_time = 2,
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rate_func = squish_rate_func(smooth, 0.5, 1),
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),
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FadeIn(block),
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]
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if winner == "Alice":
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last_fraud_block = block_copy
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else:
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last_valid_block = block_copy
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anims.append(Broadcast(block, run_time = 2))
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self.play(*anims)
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#####
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def dither(self, time = 1):
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self.play(
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Animation(VGroup(*self.foreground_mobjects)),
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run_time = time
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)
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def update_frame(self, *args, **kwargs):
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self.update_proofs_of_work()
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Scene.update_frame(self, *args, **kwargs)
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def update_proofs_of_work(self):
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self.proof_of_work_update_counter += 1
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if self.proof_of_work_update_counter%self.n_frames_per_pow != 0:
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return
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for proof_of_work in self.proofs_of_work:
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new_pow = self.get_rand_int_mob()
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new_pow.replace(proof_of_work, dim_to_match = 1)
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Transform(proof_of_work, new_pow).update(1)
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def get_rand_int_mob(self):
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e = self.n_proof_of_work_digits
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return Integer(random.randint(10**e, 10**(e+1)))
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def clean_fraud_block_content(self):
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content = self.fraud_block.content
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payments = content[1]
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content.remove(payments)
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transactions = self.get_block_filler(self.fraud_block)
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content.add(transactions)
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def get_block_filler(self, block):
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result = TextMobject("$\\langle$Transactions$\\rangle$")
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result.scale_to_fit_width(0.8*block.get_width())
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result.move_to(block)
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return result
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