I've read the linked document, but this feels like magic to me. Is the general idea something like : i can hear the CPU is doing 10 additions, then 20 substractions, twenty times in a row, so i can tell by knowing the algorithm used that the CPU is computing a public key and that it must be between 1 billion and 1.5 billion ?
No, more like the CPU will, in some cases, need to do more work if the key is X and less work if the key is Y, and we specially craft our plain-text to have many X/Y pairs as possible, so that we can hear the capacitors working harder when decrypting.
Comments
I've read the linked document, but this feels like magic to me. Is the general idea something like : i can hear the CPU is doing 10 additions, then 20 substractions, twenty times in a row, so i can tell by knowing the algorithm used that the CPU is computing a public key and that it must be between 1 billion and 1.5 billion ?
No, more like the CPU will, in some cases, need to do more work if the key is X and less work if the key is Y, and we specially craft our plain-text to have many X/Y pairs as possible, so that we can hear the capacitors working harder when decrypting.