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Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the insecure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

This is not really a limitation of asymmetric encryption, just a limitation on cryptography itselfsecurity. You can't really hold a secure conversation with someone without "meeting" them first, or meeting someone that they trust. Otherwise you could be having an encrypted conversation with anybody, which really defeats the purpose of encryption.

Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the insecure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

This is not really a limitation of asymmetric encryption, just a limitation on cryptography itself. You can't really hold a secure conversation with someone without "meeting" them first, or meeting someone that they trust.

Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the insecure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

This is not really a limitation of asymmetric encryption, just a limitation on security. You can't really hold a secure conversation with someone without "meeting" them first, or meeting someone that they trust. Otherwise you could be having an encrypted conversation with anybody, which really defeats the purpose of encryption.

2 added 2 characters in body
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Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the secureinsecure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

This is not really a limitation of asymmetric encryption, just a limitation on cryptography itself. You can't really hold a secure conversation with someone without "meeting" them first, or meeting someone that they trust.

Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the secure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the insecure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)

This is not really a limitation of asymmetric encryption, just a limitation on cryptography itself. You can't really hold a secure conversation with someone without "meeting" them first, or meeting someone that they trust.

1
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Alice and Bernard need to do at least one of three things:

  1. Exchange keys using another secure channel (perhaps they might have to meet in person)
  2. Exchange keys over the insecure channel, but use a web of trust to verify the keys (they each need to sufficiently trust someone else's keys who trusts someone else's keys, ad nauseum until it forms a path between Alice and Bernard)
  3. Exchange keys over the insecure channel, and then transmit an unforgeable message over the secure channel verifying each others' keys (in practice this may be done by reading a short nonce number out loud over a voice connection on that insecure channel, and checking if both ends have the same nonce, but this only works if you consider human voices to be unforgeable, which may not be true)