Quantum Information Exchange (QIX)

In QKD mode, the proxy receives quantum keys via the serial port in a binary format called QIX.

The frame consists of the following fields:

[sync][key id][key data][status][crc]

• sync is the 2-byte constant {0x5A, 0xA5}
• key id is an unsigned 64-bit key identifier that increments
• key data is the 256-bit random key
• status is a one byte value where:
  • 0x01 - OK: key is safe to use
  • 0xFF - Compromised: key should not be used
  • All other values are undefined and should be consider compromised
• crc is the 32-bit Castagnoli CRC used in the SSP21 standard, calculated over the key id, key data, and status fields

QIX Emulator

The project includes a command line application called qix-emulator that can read and write frames via a serial port.

> qix-emulator --help

       -h, --help
           shows this help message
       -r, --read
           read QIX frames
       -w, --write
           write random QIX frames
       -d, --stdin
           read lines of key data from stdin and write the specified port
       -m, --twrite
           write time-based QIX frames modulo n milliseconds
       -p, --port
           serial port
       -t, --rate
           number of keys per second (write only) - defaults to 1
       -c, --count
           number of frames to transmit (write only) - defaults to 2^64 -1

Simulating a serial port

For testing purposes, you can use socat to create a virtual null-modem serial port pair:

> socat -d -d pty,raw,echo=0 pty,raw,echo=0
2019/05/08 13:02:31 socat[50869] N PTY is /dev/pts/1
2019/05/08 13:02:31 socat[50869] N PTY is /dev/pts/2
2019/05/08 13:02:31 socat[50869] N starting data transfer loop with FDs [5,5] and [7,7]

Reading and writing random frames

You can then start writing and reading on each end of the null-modem pair:

> ./cpp/exe/qix-emulator/qix-emulator -w -p /dev/pts/1
wrote: 0 - ok - 7F 24 C9 E1 91 50 1B 27 24 74 BD 0E ED F9 2D 2F 2B 7A 70 8D 7F DB CB 1D ED 5E 72 51 00 05 EA 0C
wrote: 1 - ok - FF 0E 81 E5 C1 A3 52 CD 43 9A E9 DF 4B 50 CC BB 98 70 7C DD A5 41 24 BB 38 B6 F6 6A 2B B2 45 E3
wrote: 2 - ok - E2 A4 53 E5 9E 88 59 BB 33 25 E8 35 71 16 9A 0D E4 C9 BE EA B1 11 52 A1 15 1A 09 67 D9 C5 DD 6D
wrote: 3 - ok - 96 D8 D8 C0 14 29 9D 00 3E 45 7B 73 0A 84 75 50 DF 94 3A DF A9 8E 24 24 98 87 9F 41 98 E8 93 48
wrote: 4 - ok - 70 0A D4 86 E0 29 93 CC 04 4D 68 A0 89 84 0C F5 EA BB 97 BD 84 0C 9F BC 68 DD 75 C2 76 B9 ED F4

> ./cpp/exe/qix-emulator/qix-emulator -r -p /dev/pts/2
read: 0 - ok - 7F 24 C9 E1 91 50 1B 27 24 74 BD 0E ED F9 2D 2F 2B 7A 70 8D 7F DB CB 1D ED 5E 72 51 00 05 EA 0C
read: 1 - ok - FF 0E 81 E5 C1 A3 52 CD 43 9A E9 DF 4B 50 CC BB 98 70 7C DD A5 41 24 BB 38 B6 F6 6A 2B B2 45 E3
read: 2 - ok - E2 A4 53 E5 9E 88 59 BB 33 25 E8 35 71 16 9A 0D E4 C9 BE EA B1 11 52 A1 15 1A 09 67 D9 C5 DD 6D
read: 3 - ok - 96 D8 D8 C0 14 29 9D 00 3E 45 7B 73 0A 84 75 50 DF 94 3A DF A9 8E 24 24 98 87 9F 41 98 E8 93 48
read: 4 - ok - 70 0A D4 86 E0 29 93 CC 04 4D 68 A0 89 84 0C F5 EA BB 97 BD 84 0C 9F BC 68 DD 75 C2 76 B9 ED F4

If you want to write the same key data to two ports to test a proxy link without QKD hardware, just supply two port arguments:

> ./qix-emulator -w -p /dev/pts/1 -p /dev/pts/2

Reading frames from stdin

The emulator can accept key data from stdin where each line of input consists of 256 1 or 0 characters:

qix-emulator -d -p /dev/pts/0
0101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

An emulator reading the QIX frames from the matching port would see:

qix-emulator -r -p /dev/pts/1
ms(1582915992228) qix-reader info    port open for reading QIX frames on: /dev/pts/1
waiting for QIX frames
press <enter> to terminate
read: 0 - ok - 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55
read: 1 - ok - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00