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pi1/01-find-range
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README.md
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README.md

Experimental Results

We have different results from the different steps taken, that we used to compare the contents of different memory ranges and later on the different approaches for the puf. Just the first step was taken on different devices, as the later approaches based on these results.

01-find-range

The first step was logging different memory ranges to kernel log to find an appropiate one for a potential puf.

Possible Address space

To locate the DRAM, we used some trial-and-error for different ranges, based on the chip documentation

  • Physical 0x30000000 works
  • Physical 0xc0000000 does not work
  • Virtual 0xc0000000 does not work
  • Physical 0x00000000 works
  • Physical 0x00000000 -> 0x000000FF looks like SDRAM Register, as from 0x000000FF on it, contents are 0x55555555

Possible Ranges

Now we read the content of the memory on different ranges and different devices several times after boot, to see which could be used as PUF

  • Base Addr: 0x00000000: Same (Device level, register + X)
  • Base Addr: 0x00e00000: Really different (Application Data?)
  • Base Addr: 0x10000000: Same (device level), Quite Similar (Both PIs)
  • Base Addr: 0x20000000: Same (device level), Similarr (Both PIs)
  • Base Addr: 0x30000000: Really different

02-inv-neumann-puf

We implemented the Von Neumann correction algorithm. We inverted it and compared after several boot, where we took a short break and a long break between the boots.

03-final-inverted-normal-neumann-puf

As after inverting it, we had a strong bias for 11, we apply the common Von Neumann correction algorithm afterwards.

File Tree

├── pi1
│   └── 01-find-range
│       ├── addr1.txt
│       └── addr2.txt
├── pi2
│   ├── 01-find-range
│   │   ├── addr1_pi2.txt
│   │   ├── addr2_pi2.txt
│   │   ├── addr3_pi2.txt
│   │   ├── addr4_pi2.txt
│   │   ├── addr5_pi2.txt
│   │   ├── addr6_pi2.txt
│   │   ├── addr_blank.txt
│   │   ├── addresses_1.txt
│   │   └── addresses_2.txt
│   ├── 02-inv-neumann-puf
│   │   ├── test1.txt
│   │   ├── test2.txt
│   │   ├── test3.txt
│   │   ├── test4.txt
│   │   ├── test5.txt
│   │   └── test6.txt
│   ├── 03-final-inverted-normal-neumann-puf
│   │   ├── test1.txt
│   │   ├── test2.txt
│   │   └── test3.txt
│   └── 03-final-inverted-normal-neumann-puf-binary
│       ├── test1.bin
│       ├── test1_binary_repr.txt
│       ├── test1_bits_only.txt
│       ├── test2.bin
│       ├── test2_binary_repr.txt
│       └── test2_bits_only.txt