How Do I Even Smart Contracts?

In diesem Talk beleuchten wir alle Facetten der Smart Contracts. Der Schwerpunkt liegt auf Ethereum, der Blockchain, die die ausführbaren Verträge popularisiert hat. Wir schauen uns an, wo sich deren Entwicklungsmethoden vom klassischen Software Engineering abheben. welche Varianten es sonst noch so gibt und wohin zukünftige Entwicklungen geben. Auch ein kurzer Exkurs in die Korrektheit von Smart Contracts darf nicht fehlen.

Transcript

1. View Slide

2. H o w D o I E v e n
   S m a r t
   C o n t r a c t s ?
   L a r s H u p e l
   I N N O Q T e c h n o l o g y N i g h t
   2 0 1 9 - 1 0 - 1 5
   

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3. E t h e r e u m
   • e i n e d e r j ü n g e r e n B l o c k c h a i n s
   • W ä h r u n g : E t h e r ( E T H )
   • P l a t z 2 – 3 i n M a r k t k a p i t a l i s i e r u n g
   • t e c h n i s c h e N e u e r u n g : P l a t t f o r m f ü r D e c e n t r a l i z e d A p p s
   

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4. D e c e n t r a l i z e d A p p s
   

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5. E t h e r e u m
   Z w e i A r t e n v o n A c c o u n t s :
   1 . E x t e r n a l l y O w n e d
   ( n a t ü r l i c h e P e r s o n )
   2 . S m a r t C o n t r a c t s
   ( j u r i s t i s c h e P e r s o n )
   

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6. S m a r t C o n t r a c t s
   

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7. S m a r t C o n t r a c t s
   . . . s i n d s p e z i e l l e A c c o u n t s m i t e i g e n e r I d e n t i t ä t u n d K o n t o s t a n d
   

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8. S m a r t C o n t r a c t s
   . . . s i n d s p e z i e l l e A c c o u n t s m i t e i g e n e r I d e n t i t ä t u n d K o n t o s t a n d
   . . . h a b e n k e i n e O w n e r s h i p
   

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9. S m a r t C o n t r a c t s
   . . . s i n d s p e z i e l l e A c c o u n t s m i t e i g e n e r I d e n t i t ä t u n d K o n t o s t a n d
   . . . h a b e n k e i n e O w n e r s h i p
   . . . e n t h a l t e n S p e i c h e r z e l l e n m i t v e r ä n d e r l i c h e n W e r t e n
   

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10. S m a r t C o n t r a c t s
    . . . s i n d s p e z i e l l e A c c o u n t s m i t e i g e n e r I d e n t i t ä t u n d K o n t o s t a n d
    . . . h a b e n k e i n e O w n e r s h i p
    . . . e n t h a l t e n S p e i c h e r z e l l e n m i t v e r ä n d e r l i c h e n W e r t e n
    . . . b e s t e h e n a u s u n v e r ä n d e r l i c h e m C o d e
    

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11. S m a r t C o n t r a c t s
    . . . s i n d s p e z i e l l e A c c o u n t s m i t e i g e n e r I d e n t i t ä t u n d K o n t o s t a n d
    . . . h a b e n k e i n e O w n e r s h i p
    . . . e n t h a l t e n S p e i c h e r z e l l e n m i t v e r ä n d e r l i c h e n W e r t e n
    . . . b e s t e h e n a u s u n v e r ä n d e r l i c h e m C o d e
    . . . k ö n n e n m i t a n d e r e n C o n t r a c t s i n t e r a g i e r e n , w e r d e n a b e r n i e
    s e l b s t s t ä n d i g a k t i v
    

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12. V e r g l e i c h : d i g i t a l e r N o t a r
    • R e c h t e u n d P f l i c h t e n
    v e r t r a g l i c h f e s t g e l e g t
    • n e u t r a l e I n s t a n z
    ü b e r w a c h t A b l a u f
    • I n t e r a k t i o n m i t d r i t t e n
    P a r t e i e n
    

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14. E t h e r e u m V i r t u a l M a c h i n e
    

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15. V i r t u e l l e M a s c h i n e n
    s i n d M i s c h f o r m e n
    z w i s c h e n I n t e r p r e t e r
    u n d C o m p i l e r
    

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16. W a s k a n n d i e E V M ?
    1 . a r i t h m e t i s c h e O p e r a t i o n e n
    2 . b i t w e i s e & l o g i s c h e O p e r a t i o n e n
    3 . H a s h e s ( m e i s t S H A - 3 )
    4 . U m g e b u n g s i n f o r m a t i o n ( K o n t o s t a n d , A u f r u f e r , . . . )
    5 . B l o c k i n f o r m a t i o n ( Z e i t s t e m p e l , B l o c k n u m m e r , . . . )
    6 . S t a c k - u n d S p e i c h e r o p e r a t i o n e n
    7 . S p r ü n g e
    8 . L o g g i n g
    9 . K o n t o o p e r a t i o n e n ( E r z e u g u n g , Z a h l u n g , A u f r u f , . . . )
    

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17. • S m a r t C o n t r a c t s w e r d e n v o n
    a l l e n M i n e r n a u s g e f ü h r t
    

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18. • S m a r t C o n t r a c t s w e r d e n v o n
    a l l e n M i n e r n a u s g e f ü h r t
    • B e r e c h n u n g d e r
    T r a n s a k t i o n s g e b ü h r a n h a n d
    d e r A u s f ü h r u n g s d a u e r
    

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19. • S m a r t C o n t r a c t s w e r d e n v o n
    a l l e n M i n e r n a u s g e f ü h r t
    • B e r e c h n u n g d e r
    T r a n s a k t i o n s g e b ü h r a n h a n d
    d e r A u s f ü h r u n g s d a u e r
    • U s e r m u s s e i n e T a n k g r ö ß e
    u n d e i n e n S p r i t p r e i s a n g e b e n
    

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20. • S m a r t C o n t r a c t s w e r d e n v o n
    a l l e n M i n e r n a u s g e f ü h r t
    • B e r e c h n u n g d e r
    T r a n s a k t i o n s g e b ü h r a n h a n d
    d e r A u s f ü h r u n g s d a u e r
    • U s e r m u s s e i n e T a n k g r ö ß e
    u n d e i n e n S p r i t p r e i s a n g e b e n
    • j e d e O p e r a t i o n h a t e i n e n
    d e f i n i e r t e n V e r b r a u c h
    

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22. P r o g r a m m i e r u n g & T o o l s
    

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23. E i n e i n f a c h e r C o n t r a c t
    608060405234801561001057600080fd5b506000808190555033600160006101000a81548173ffff
    ffffffffffffffffffffffffffffffffffff021916908373ffffffffffffffffffffffffffffffff
    ffffffff1602179055506101be806100686000396000f30060806040526004361061004c57600035
    7c0100000000000000000000000000000000000000000000000000000000900463ffffffff168063
    3ccfd60b146100515780638f9595d414610068575b600080fd5b34801561005d57600080fd5b5061
    0066610086565b005b61007061011d565b6040518082815260200191505060405180910390f35b60
    0160009054906101000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffff
    ffffffffffffffffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614
    15156100e257600080fd5b600160009054906101000a900473ffffffffffffffffffffffffffffff
    ffffffffff1673ffffffffffffffffffffffffffffffffffffffff16ff5b60006001600090549061
    01000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffff
    ffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614151561017b5760
    0080fd5b3460008082825401925050819055506000549050905600a165627a7a72305820b4d2d5a2
    acfa0e197908c7c57826d35a987f64b29f8b97020a4ca96f63ce66630029
    

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24. E i n e i n f a c h e r C o n t r a c t
    608060405234801561001057600080fd5b506000808190555033600160006101000a81548173ffff
    ffffffffffffffffffffffffffffffffffff021916908373ffffffffffffffffffffffffffffffff
    ffffffff1602179055506101be806100686000396000f30060806040526004361061004c57600035
    7c0100000000000000000000000000000000000000000000000000000000900463ffffffff168063
    3ccfd60b146100515780638f9595d414610068575b600080fd5b34801561005d57600080fd5b5061
    0066610086565b005b61007061011d565b6040518082815260200191505060405180910390f35b60
    0160009054906101000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffff
    ffffffffffffffffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614
    15156100e257600080fd5b600160009054906101000a900473ffffffffffffffffffffffffffffff
    ffffffffff1673ffffffffffffffffffffffffffffffffffffffff16ff5b60006001600090549061
    01000a900473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffff
    ffffffffffffffff163373ffffffffffffffffffffffffffffffffffffffff1614151561017b5760
    0080fd5b3460008082825401925050819055506000549050905600a165627a7a72305820b4d2d5a2
    acfa0e197908c7c57826d35a987f64b29f8b97020a4ca96f63ce66630029
    

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25. S o l i d i t y
    • p o p u l ä r s t e H o c h s p r a c h e f ü r E V M - B y t e c o d e
    • g e t y p t , o b j e k t o r i e n t i e r t
    • s y n t a k t i s c h a n J a v a s c r i p t a n g e l e h n t
    

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26. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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27. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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28. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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29. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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30. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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31. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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32. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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33. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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34. pragma solidity ^0.4.22;
    contract Wallet {
    uint256 balance;
    address owner;
    constructor () public {
    balance = 0;
    owner = msg.sender;
    }
    function addfund() payable public returns (uint256) {
    require (msg.sender == owner);
    balance += msg.value;
    return balance;
    }
    function withdraw() public {
    require (msg.sender == owner);
    selfdestruct(owner);
    }
    }
    

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35. M e t a m a s k
    • B r o w s e r - P l u g i n z u r V e r w a l t u n g v o n
    E t h e r e u m - A d r e s s e n
    • k o m m u n z i e r t ü b e r R P C m i t B l o c k c h a i n - K n o t e n
    • i n t e g r i e r t m i t w e b 3 . j s
    

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36. View Slide

37. B e i s p i e l e
    

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38. B e i s p i e l e
    

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39. B e i s p i e l e
    • M u l t i - S i g n a t u r - W a l l e t s
    

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40. B e i s p i e l e
    • M u l t i - S i g n a t u r - W a l l e t s
    • E R C - 2 0 - T o k e n
    

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41. B e i s p i e l e
    • M u l t i - S i g n a t u r - W a l l e t s
    • E R C - 2 0 - T o k e n
    • H a n d e l s b ö r s e n
    

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42. B e i s p i e l e
    • M u l t i - S i g n a t u r - W a l l e t s
    • E R C - 2 0 - T o k e n
    • H a n d e l s b ö r s e n
    • W e t t e n
    

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43. B e i s p i e l e
    • M u l t i - S i g n a t u r - W a l l e t s
    • E R C - 2 0 - T o k e n
    • H a n d e l s b ö r s e n
    • W e t t e n
    • C r y p t o k i t t i e s
    

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44. K o m p o n e n t e n e i n e r D a p p
    • W e b a p p l i k a t i o n m i t J S ( m e i s t o p e n s o u r c e )
    • S m a r t C o n t r a c t ( s )
    • B l o c k c h a i n
    

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45. S o f t w a r e q u a l i t ä t
    

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46. E n t w i c k l u n g s - W o r k f l o w
    

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47. E n t w i c k l u n g s - W o r k f l o w
    1 . C o n t r a c t i n S o l i d i t y e n t w i c k e l n
    

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48. E n t w i c k l u n g s - W o r k f l o w
    1 . C o n t r a c t i n S o l i d i t y e n t w i c k e l n
    2 . m i t R e m i x / M e t a m a s k a u s r o l l e n
    

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49. E n t w i c k l u n g s - W o r k f l o w
    1 . C o n t r a c t i n S o l i d i t y e n t w i c k e l n
    2 . m i t R e m i x / M e t a m a s k a u s r o l l e n
    3 . ? ? ?
    

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50. • S m a r t C o n t r a c t s s i n d
    u n v e r ä n d e r l i c h
    

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51. • S m a r t C o n t r a c t s s i n d
    u n v e r ä n d e r l i c h
    • T r a n s a k t i o n e n s i n d e n d g ü l t i g
    

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52. • S m a r t C o n t r a c t s s i n d
    u n v e r ä n d e r l i c h
    • T r a n s a k t i o n e n s i n d e n d g ü l t i g
    • e s g i b t k e i n e K o n t r o l l i n s t a n z
    *
    

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53. • S m a r t C o n t r a c t s s i n d
    u n v e r ä n d e r l i c h
    • T r a n s a k t i o n e n s i n d e n d g ü l t i g
    • e s g i b t k e i n e K o n t r o l l i n s t a n z
    *
    • F e h l e r s i n d n i c h t k o r r i g i e r b a r
    *
    

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54. F a t a l e F e h l e r
    T h e D A O ( 2 0 1 6 )
    • D e c e n t r a l i z e d A u t o n o m o u s O r g a n i z a t i o n
    • e i n e A r t d i g i t a l e r G e b e r v o n W a g n i s k a p i t a l
    • I d e e : I n v e s t o r * i n n e n s t i m m e n ü b e r K a p i t a l n u t z u n g a b
    • B u g i m C o n t r a c t f ü h r t e z u m A b g r e i f e n v o n 5 0 M i l l i o n e n U S D
    

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55. F a t a l e F e h l e r
    P a r i t y W a l l e t ( 2 0 1 7 )
    • O n l i n e W a l l e t f ü r E t h e r u n d a n d e r e T o k e n
    • B u g i m C o n t r a c t f ü h r t e z u m A b g r e i f e n v o n 3 0 M i l l i o n e n U S D
    

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56. F a t a l e F e h l e r
    P a r i t y W a l l e t ( 2 0 1 7 )
    • O n l i n e W a l l e t f ü r E t h e r u n d a n d e r e T o k e n
    • B u g i m C o n t r a c t f ü h r t e z u m A b g r e i f e n v o n 3 0 M i l l i o n e n U S D
    • w e i t e r e r B u g f ü h r t e z u m T o t a l v e r l u s t v o n 3 6 0 M i l l i o n e n U S D
    

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57. Q u a l i t ä t s s i c h e r u n g
    T r u f f l e : F r a m e w o r k f ü r d e n g e s a m t e n E n t w i c k l u n g s z y k l u s
    • T e s t i n g ( S o l i d i t y u n d J a v a S c r i p t )
    • D e p l o y m e n t
    • M i g r a t i o n s
    

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58. C o d e i s L a w
    “ H o w e v e r , t h e s e m o r e c o m p l e x a g r e e m e n t s , w i t h g r e a t e r e n g a g e m e n t
    w i t h r e a l w o r l d g o o d s a n d s e r v i c e s , h i g h l i g h t t h e n e c e s s i t y o f e f f e c t i v e
    d i s p u t e r e s o l u t i o n , a s w e l l a s i n d i c a t e a n e c e s s a r y i n t e r r e l a t i o n w i t h
    t e r r i t o r i a l l e g a l s y s t e m s .
    

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59. C o d e i s L a w
    “ H o w e v e r , t h e s e m o r e c o m p l e x a g r e e m e n t s , w i t h g r e a t e r e n g a g e m e n t
    w i t h r e a l w o r l d g o o d s a n d s e r v i c e s , h i g h l i g h t t h e n e c e s s i t y o f e f f e c t i v e
    d i s p u t e r e s o l u t i o n , a s w e l l a s i n d i c a t e a n e c e s s a r y i n t e r r e l a t i o n w i t h
    t e r r i t o r i a l l e g a l s y s t e m s .
    C o n t e s t a t i o n m e c h a n i s m s a r e n e c e s s a r y t o ‘ s o f t e n ’ t h e e f f e c t s o f s e l f -
    e x e c u t i n g ‘ s m a r t c o n t r a c t s ’, a n d m a k e t r a n s a c t i o n s r e v e r s i b l e , a l l o w -
    i n g t h e o u t c o m e s o f d i s p u t e r e s o l u t i o n t o b e e n f o r c e d .
    ”
    G o l d e n f e i n & L a t e r : “ L e g a l E n g i n e e r i n g o n t h e B l o c k c h a i n : ‘ S m a r t C o n t r a c t s ’ a s L e g a l C o n d u c t ” ( 2 0 1 8 )
    

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60. H ü r d e n f ü r S m a r t C o n t r a c t s
    • b i s h e r k e i n e e t a b l i e r t e n f o r m a l e n M e t h o d e n
    • u n k l a r e J u r i s d i k t i o n
    • N a c h v o l l z i e h b a r k e i t d e s C o d e s
    

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61. S m a r t C o n t r a c t s ?
    “ T h e r e a r e o n l y t w o t h i n g s y o u n e e d t o k n o w a b o u t s m a r t c o n t r a c t s :
    1 . T h e y ’ r e n o t s m a r t .
    2 . T h e y ’ r e n o t c o n t r a c t s . ”
    P h i l i p W a d l e r ( a t F u l l S t a c k F e s t : https://twitter.com/steveklabnik/status/1169599735956672513)
    

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62. R u s t & W e b A s s e m b l y
    

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63. R u s t & W e b A s s e m b l y
    R u s t
    • m a s c h i n e n n a h e S p r a c h e v o n
    M o z i l l a
    • F o k u s a u f S p e i c h e r s i c h e r h e i t
    • k e i n G C
    �
    W e b A s s e m b l y
    • A s s e m b l e r s p r a c h e f ü r d e n
    B r o w s e r
    • l ä u f t i n d e r J S - S a n d b o x
    • k e i n Z u g r i f f a u f d e n D O M
    

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64. E W A S M
    • W e b A s s e m b l y a u f d e r E V M :
    v i e l v e r s p r e c h e n d e E n t w i c k l u n g
    • d e r z e i t n o c h u n s p e z i f i z i e r t
    • e x p e r i m e n t e l l e I m p l e m e n t i e r u n g i n
    P a r i t y
    

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65. F a z i t
    

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66. F a z i t
    • E t h e r e u m i s t b i s h e r g r ö ß t e P l a t t f o r m f ü r D a p p s
    • h o h e E n t w i c k l u n g s g e s c h w i n d i g k e i t
    • l e i d e t a n m a n g e l h a f t e m S p r a c h d e s i g n
    • P r o o f o f A u t h o r i t y u n d E W A S M v i e l v e r s p r e c h e n d , a b e r n o c h i n d e n
    K i n d e r s c h u h e n
    

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67. Q & A
    L a r s H u p e l
    �
    l a r s . h u p e l @ i n n o q . c o m
    � @ l a r s r _ h
    w w w . i n n o q . c o m
    i n n o Q D e u t s c h l a n d G m b H
    K r i s c h e r s t r . 1 0 0
    4 0 7 8 9 M o n h e i m a . R h .
    G e r m a n y
    + 4 9 2 1 7 3 3 3 6 6 - 0
    O h l a u e r S t r . 4 3
    1 0 9 9 9 B e r l i n
    G e r m a n y
    L u d w i g s t r . 1 8 0 E
    6 3 0 6 7 O f f e n b a c h
    G e r m a n y
    K r e u z s t r . 1 6
    8 0 3 3 1 M ü n c h e n
    G e r m a n y
    c / o W e W o r k
    H e r m a n n s t r a s s e 1 3
    2 0 0 9 5 H a m b u r g
    G e r m a n y
    i n n o Q S c h w e i z G m b H
    G e w e r b e s t r . 1 1
    C H - 6 3 3 0 C h a m
    S w i t z e r l a n d
    + 4 1 4 1 7 4 3 0 1 1 1
    A l b u l a s t r . 5 5
    8 0 4 8 Z ü r i c h
    S w i t z e r l a n d
    

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68. L A R S H U P E L
    C o n s u l t a n t
    i n n o Q D e u t s c h l a n d G m b H
    L a r s e n j o y s p r o g r a m m i n g i n a v a r i e t y o f l a n -
    g u a g e s , i n c l u d i n g S c a l a , H a s k e l l , a n d R u s t . H e i s
    k n o w n a s a f r e q u e n t c o n f e r e n c e s p e a k e r a n d o n e
    o f t h e f o u n d e r s o f t h e T y p e l e v e l i n i t i a t i v e w h i c h
    i s d e d i c a t e d t o p r o v i d i n g p r i n c i p l e d , t y p e - d r i v e n
    S c a l a l i b r a r i e s .
    

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69. B i l d q u e l l e n
    P y r a m i d e :
    https://pixabay.com/illustrations/pyramid-
    sky-reflection-ancient-1076828/
    D e c e n t r a l i z e d A p p s : https:
    //medium.com/swlh/understanding-dapps-
    decentralized-applications-8f3668ebdc9a
    S m a r t C o n t r a c t : http://instaco.de/,
    https://www.ethereum.org/token
    A k t e n : https://pixabay.com/photos/files-
    ddr-archive-1633406/
    E t h e r e u m T r a n s a c t i o n s :
    https://medium.com/@preethikasireddy/how-
    does-ethereum-work-anyway-22d1df506369
    P l a t i n e :
    https://commons.wikimedia.org/wiki/File:
    Computer_Circuit_Board_MOD_45153619.jpg,
    H a r l a n d Q u a r r i n g t o n , O G L 1 . 0
    G a s P u m p :
    https://commons.wikimedia.org/wiki/File:
    Antique_yard_vintage_gas_pumps,_Washington_
    LCCN2010630650.tif, L i b r a r y o f C o n g r e s s
    T r e a t y o f R o m e :
    https://en.wikipedia.org/wiki/File:
    Treaty_of_Rome.jpg, a u t h o r u n k n o w n
    S c a r e d c a t :
    https://pixabay.com/vectors/cat-scared-
    hunched-spooky-black-30788/
    C o i n s : https://pixabay.com/photos/money-
    coins-euro-coins-currency-515058/
    R a t i f i k a t i o n d e s G r u n d g e s e t z e s : https:
    //de.wikipedia.org/w/index.php?title=Datei:
    Grundgesetz_Ratifikationsunterschriften.
    jpg&filetimestamp=20110526174813&
    N Y S E : https://pixabay.com/photos/stock-
    exchange-trading-floor-738671/
    P o k e r c h i p s :
    https://pixabay.com/photos/chips-play-
    poker-casino-gambling-2038348/
    C o n t r a c t U M L : https://github.com/Azure-
    Samples/blockchain/blob/master/ledger/
    template/ethereum-on-azure/permissioning-
    contracts/validation-set/media/contract-
    uml.png
    S e r v e r r a c k :
    https://pixabay.com/photos/server-cloud-
    development-business-1235959/
    L i g h t n i n g :
    https://pixabay.com/photos/lightning-storm-
    weather-sky-399853/
    F e r r i s t h e C r a b :
    https://www.rust-lang.org/what/wasm, M I T
    C o n s t r u c t i o n s i t e :
    https://pixabay.com/photos/building-
    construction-site-cranes-768815/
    R a i l r o a d : https://pixabay.com/photos/track-
    railway-line-rail-traffic-3670209/
    

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