4 ms·

This kinda raises question. I for one would not use encryption just to maximize bandwith efficiency. Deep space program are no where close to being a tactical a

by pothibo 14y ago

This kinda raises question. I for one would not use encryption just to maximize bandwith efficiency. Deep space program are no where close to being a tactical advantage over another country. I wouldn't see why someone would like to screw it up. On the other side, there's always a moron out there to crash the party. So even if I wouldn't use encryption, I wouldn't be surprised if they use it.

nitrogen 14y ago
I for one would not use encryption just to maximize bandwith efficiency. Encryption typically doesn't make messages longer.
- pothibo 14y ago
  We're not talking about your average data. We're talking about optimized data. Of course there's an overhead. EDIT: removed specific type of data
  - accountoftheday 14y ago
    There isn't. You could easily achieve zero overhead by shipping a rover with a OTP for time-keyed IVs and just not do any padding.
  - nitrogen 14y ago
    I'm not sure what you mean by "optimized" data. Edit: my very rudimentary understanding of information theory tells me that there's no "average" or "optimized" data, only varying amounts of entropy (AKA compressibility). My limited knowledge of radio and electrical transmission says that transmitted data is encoded to make effective use of the transmission medium (e.g. 8b/10b encoding, 8-to-14 modulation, TMDS). So, if by "optimized" data you mean "high entropy" data, encryption should have no effect on that. Or, if by "optimized" you mean encoded for the transmission channel, you would run your encryption process before the channel encoding process.
    - deleted 14y ago
      [deleted]
    - pothibo 14y ago
      At first, I wouldn't have thought that they would use encoding to maximize efficiency. But now that I think about it, their goal isn't efficiency but rather consistency. So yeah I was wrong. Maybe I thought this was more primitive than what it really is :/
      - nitrogen 14y ago
        You seem to be trying to say something, but it's not coming across. What is primitive? How is it primitive? How do you describe the difference between efficiency and consistency in your usage? Is English not your primary language? My exposure to this stuff is limited to a few exercises in a Matlab class years ago, plus what I read on HN and Wikipedia. Based on what I understand, from a data transmission perspective, there is no difference between efficiency and consistency. There is a theoretical maximum amount of data that can be transmitted using a given medium, bandwidth, and error rate. The only goal is to get as close to that maximum as possible. Also, there's no shame in admitting you're wrong. In fact, every opportunity to be wrong is an opportunity to learn.
        pothibo 14y ago
        Yeah, english isn't my primary language and I haven't spoken it in a long time so sorry if I can't make my point across :) I'm not ashamed for being wrong. If that'd be the case I would have been ashamed my whole life heh. When I said consistency I was referring to low-error rate in the signal. I should have said that but couldn't find the correct word for it. Efficiency meant efficiency in the bandwidth usage. So in that sense, there's always a tradeoff between efficiency (use 100% of the bandwidth to transmit real data) and consistency (make sure that 100% of the sent data is error-free) Now, when I first wrote my comment. I had the feeling that communication was very basic commands. like a 2 bit integer for movement direction (00 up, 01 down, 10 left, 11right). So if you'd use such a scheme to communicate instruction to the rover, there would be an obvious overhead (encoding 2 bit into 4, 10, etc). But now that I really think about it, instruction sent to the rover are probably very complex, which increase entropy, which in the end, made my first assumption wrong, is this clear? I hope it is ;) If not, I can rephrase !

by pothibo 14y ago

nitrogen 14y ago

I for one would not use encryption just to maximize bandwith efficiency. Encryption typically doesn't make messages longer.

pothibo 14y ago
We're not talking about your average data. We're talking about optimized data. Of course there's an overhead. EDIT: removed specific type of data
- accountoftheday 14y ago
  There isn't. You could easily achieve zero overhead by shipping a rover with a OTP for time-keyed IVs and just not do any padding.
- nitrogen 14y ago
  I'm not sure what you mean by "optimized" data. Edit: my very rudimentary understanding of information theory tells me that there's no "average" or "optimized" data, only varying amounts of entropy (AKA compressibility). My limited knowledge of radio and electrical transmission says that transmitted data is encoded to make effective use of the transmission medium (e.g. 8b/10b encoding, 8-to-14 modulation, TMDS). So, if by "optimized" data you mean "high entropy" data, encryption should have no effect on that. Or, if by "optimized" you mean encoded for the transmission channel, you would run your encryption process before the channel encoding process.
  - deleted 14y ago
    [deleted]
  - pothibo 14y ago
    At first, I wouldn't have thought that they would use encoding to maximize efficiency. But now that I think about it, their goal isn't efficiency but rather consistency. So yeah I was wrong. Maybe I thought this was more primitive than what it really is :/
    - nitrogen 14y ago
      You seem to be trying to say something, but it's not coming across. What is primitive? How is it primitive? How do you describe the difference between efficiency and consistency in your usage? Is English not your primary language? My exposure to this stuff is limited to a few exercises in a Matlab class years ago, plus what I read on HN and Wikipedia. Based on what I understand, from a data transmission perspective, there is no difference between efficiency and consistency. There is a theoretical maximum amount of data that can be transmitted using a given medium, bandwidth, and error rate. The only goal is to get as close to that maximum as possible. Also, there's no shame in admitting you're wrong. In fact, every opportunity to be wrong is an opportunity to learn.
      - pothibo 14y ago
        Yeah, english isn't my primary language and I haven't spoken it in a long time so sorry if I can't make my point across :) I'm not ashamed for being wrong. If that'd be the case I would have been ashamed my whole life heh. When I said consistency I was referring to low-error rate in the signal. I should have said that but couldn't find the correct word for it. Efficiency meant efficiency in the bandwidth usage. So in that sense, there's always a tradeoff between efficiency (use 100% of the bandwidth to transmit real data) and consistency (make sure that 100% of the sent data is error-free) Now, when I first wrote my comment. I had the feeling that communication was very basic commands. like a 2 bit integer for movement direction (00 up, 01 down, 10 left, 11right). So if you'd use such a scheme to communicate instruction to the rover, there would be an obvious overhead (encoding 2 bit into 4, 10, etc). But now that I really think about it, instruction sent to the rover are probably very complex, which increase entropy, which in the end, made my first assumption wrong, is this clear? I hope it is ;) If not, I can rephrase !