Lightning Network: asymmetry in the information tracked by each participant?












3














In following paper, written by Christian Decker et al., there is a paragraph that is not clear to me.



eltoo: A Simple Layer2 Protocol for Bitcoin




"The central idea of Lightning is to invalidate an old state by
punishing the participant publishing it, and claiming all the funds in
the channel. This however introduces an intrinsic asymmetry in the
information tracked by each participant. The replaced states turn into
toxic information
as soon as they are replaced, and leaking that
information may result in funds being stolen. The asymmetry also
limits Lightning to two participants."




There are following points that are not clear to me:



(1) Does asymmetry mean the information tracked by each participant (payer and recipient) are NOT the same (or are NOT equal)?



(2) What is the reason of this asymmetry?



(3) What does "turn into toxic information" mean?



(4) The last sentence: "asymmetry also limits Lightning to two participants", Does it mean that we can expect a payment transaction can have more than two participants? since a payment logically has only two participants: a payer and a recipient.










share|improve this question





























    3














    In following paper, written by Christian Decker et al., there is a paragraph that is not clear to me.



    eltoo: A Simple Layer2 Protocol for Bitcoin




    "The central idea of Lightning is to invalidate an old state by
    punishing the participant publishing it, and claiming all the funds in
    the channel. This however introduces an intrinsic asymmetry in the
    information tracked by each participant. The replaced states turn into
    toxic information
    as soon as they are replaced, and leaking that
    information may result in funds being stolen. The asymmetry also
    limits Lightning to two participants."




    There are following points that are not clear to me:



    (1) Does asymmetry mean the information tracked by each participant (payer and recipient) are NOT the same (or are NOT equal)?



    (2) What is the reason of this asymmetry?



    (3) What does "turn into toxic information" mean?



    (4) The last sentence: "asymmetry also limits Lightning to two participants", Does it mean that we can expect a payment transaction can have more than two participants? since a payment logically has only two participants: a payer and a recipient.










    share|improve this question



























      3












      3








      3







      In following paper, written by Christian Decker et al., there is a paragraph that is not clear to me.



      eltoo: A Simple Layer2 Protocol for Bitcoin




      "The central idea of Lightning is to invalidate an old state by
      punishing the participant publishing it, and claiming all the funds in
      the channel. This however introduces an intrinsic asymmetry in the
      information tracked by each participant. The replaced states turn into
      toxic information
      as soon as they are replaced, and leaking that
      information may result in funds being stolen. The asymmetry also
      limits Lightning to two participants."




      There are following points that are not clear to me:



      (1) Does asymmetry mean the information tracked by each participant (payer and recipient) are NOT the same (or are NOT equal)?



      (2) What is the reason of this asymmetry?



      (3) What does "turn into toxic information" mean?



      (4) The last sentence: "asymmetry also limits Lightning to two participants", Does it mean that we can expect a payment transaction can have more than two participants? since a payment logically has only two participants: a payer and a recipient.










      share|improve this question















      In following paper, written by Christian Decker et al., there is a paragraph that is not clear to me.



      eltoo: A Simple Layer2 Protocol for Bitcoin




      "The central idea of Lightning is to invalidate an old state by
      punishing the participant publishing it, and claiming all the funds in
      the channel. This however introduces an intrinsic asymmetry in the
      information tracked by each participant. The replaced states turn into
      toxic information
      as soon as they are replaced, and leaking that
      information may result in funds being stolen. The asymmetry also
      limits Lightning to two participants."




      There are following points that are not clear to me:



      (1) Does asymmetry mean the information tracked by each participant (payer and recipient) are NOT the same (or are NOT equal)?



      (2) What is the reason of this asymmetry?



      (3) What does "turn into toxic information" mean?



      (4) The last sentence: "asymmetry also limits Lightning to two participants", Does it mean that we can expect a payment transaction can have more than two participants? since a payment logically has only two participants: a payer and a recipient.







      security lightning-network payment terminology






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited 1 hour ago

























      asked 3 hours ago









      sas

      333213




      333213






















          1 Answer
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          2














          When two channel participants open a channel or update it, they exchange commitment transactions. Each of these commitment transactions allows one party to unilaterally close the channel.



          The commitment transactions are asymmetric in that they lock the closing party's funds when broadcasted, i.e. Alice's commitment transaction locks Alice's funds, Bob's commitment transaction locks Bob's funds. The counterparty's funds are immediately available for spending. The lock on the closing party's funds gives the counterparty time to impound the closing party's funds if an outdated state was broadcast.



          Once a channel is updated, the outdated channel state is "toxic" in the sense that (accidentally) using the outdated commitment transaction to close the channel will cost the user all their funds in the channel.



          Updating a channel to make a payment in the punishment-based channel setup requires a procedure with multiple roundtrips in a specific order to ensure that there is no disadvantageous intermittent state for either party. If it were possible to map this on a multiparty setup, it would be extremely complex. In Eltoo broadcasting an outdated state is dealt with by updating to the latest state. Since channel state can thusly be symmetric, it is trivial to have channels with more than two parties.






          share|improve this answer





















          • Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
            – sas
            23 mins ago











          Your Answer








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          1 Answer
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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2














          When two channel participants open a channel or update it, they exchange commitment transactions. Each of these commitment transactions allows one party to unilaterally close the channel.



          The commitment transactions are asymmetric in that they lock the closing party's funds when broadcasted, i.e. Alice's commitment transaction locks Alice's funds, Bob's commitment transaction locks Bob's funds. The counterparty's funds are immediately available for spending. The lock on the closing party's funds gives the counterparty time to impound the closing party's funds if an outdated state was broadcast.



          Once a channel is updated, the outdated channel state is "toxic" in the sense that (accidentally) using the outdated commitment transaction to close the channel will cost the user all their funds in the channel.



          Updating a channel to make a payment in the punishment-based channel setup requires a procedure with multiple roundtrips in a specific order to ensure that there is no disadvantageous intermittent state for either party. If it were possible to map this on a multiparty setup, it would be extremely complex. In Eltoo broadcasting an outdated state is dealt with by updating to the latest state. Since channel state can thusly be symmetric, it is trivial to have channels with more than two parties.






          share|improve this answer





















          • Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
            – sas
            23 mins ago
















          2














          When two channel participants open a channel or update it, they exchange commitment transactions. Each of these commitment transactions allows one party to unilaterally close the channel.



          The commitment transactions are asymmetric in that they lock the closing party's funds when broadcasted, i.e. Alice's commitment transaction locks Alice's funds, Bob's commitment transaction locks Bob's funds. The counterparty's funds are immediately available for spending. The lock on the closing party's funds gives the counterparty time to impound the closing party's funds if an outdated state was broadcast.



          Once a channel is updated, the outdated channel state is "toxic" in the sense that (accidentally) using the outdated commitment transaction to close the channel will cost the user all their funds in the channel.



          Updating a channel to make a payment in the punishment-based channel setup requires a procedure with multiple roundtrips in a specific order to ensure that there is no disadvantageous intermittent state for either party. If it were possible to map this on a multiparty setup, it would be extremely complex. In Eltoo broadcasting an outdated state is dealt with by updating to the latest state. Since channel state can thusly be symmetric, it is trivial to have channels with more than two parties.






          share|improve this answer





















          • Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
            – sas
            23 mins ago














          2












          2








          2






          When two channel participants open a channel or update it, they exchange commitment transactions. Each of these commitment transactions allows one party to unilaterally close the channel.



          The commitment transactions are asymmetric in that they lock the closing party's funds when broadcasted, i.e. Alice's commitment transaction locks Alice's funds, Bob's commitment transaction locks Bob's funds. The counterparty's funds are immediately available for spending. The lock on the closing party's funds gives the counterparty time to impound the closing party's funds if an outdated state was broadcast.



          Once a channel is updated, the outdated channel state is "toxic" in the sense that (accidentally) using the outdated commitment transaction to close the channel will cost the user all their funds in the channel.



          Updating a channel to make a payment in the punishment-based channel setup requires a procedure with multiple roundtrips in a specific order to ensure that there is no disadvantageous intermittent state for either party. If it were possible to map this on a multiparty setup, it would be extremely complex. In Eltoo broadcasting an outdated state is dealt with by updating to the latest state. Since channel state can thusly be symmetric, it is trivial to have channels with more than two parties.






          share|improve this answer












          When two channel participants open a channel or update it, they exchange commitment transactions. Each of these commitment transactions allows one party to unilaterally close the channel.



          The commitment transactions are asymmetric in that they lock the closing party's funds when broadcasted, i.e. Alice's commitment transaction locks Alice's funds, Bob's commitment transaction locks Bob's funds. The counterparty's funds are immediately available for spending. The lock on the closing party's funds gives the counterparty time to impound the closing party's funds if an outdated state was broadcast.



          Once a channel is updated, the outdated channel state is "toxic" in the sense that (accidentally) using the outdated commitment transaction to close the channel will cost the user all their funds in the channel.



          Updating a channel to make a payment in the punishment-based channel setup requires a procedure with multiple roundtrips in a specific order to ensure that there is no disadvantageous intermittent state for either party. If it were possible to map this on a multiparty setup, it would be extremely complex. In Eltoo broadcasting an outdated state is dealt with by updating to the latest state. Since channel state can thusly be symmetric, it is trivial to have channels with more than two parties.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 1 hour ago









          Murch

          34.6k27112324




          34.6k27112324












          • Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
            – sas
            23 mins ago


















          • Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
            – sas
            23 mins ago
















          Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
          – sas
          23 mins ago




          Thank you. Just when you say we can have channels with more than two parties, do you mean that we can have a bidirectional payment channel between e.g. 4 participants (payer/recipient) like this figure? ( imgur.com/5KVLP6G ) Or do you mean something else? And does eltoo such a capability? Thanks
          – sas
          23 mins ago


















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