306 lines
11 KiB
C
306 lines
11 KiB
C
/* Driver for the Infinite Noise Multiplier USB stick */
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// Required to include clock_gettime
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#define _POSIX_C_SOURCE 200809L
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#include <stdint.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <ftdi.h>
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#include "infnoise.h"
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#include "KeccakF-1600-interface.h"
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// Extract the INM output from the data received. Basically, either COMP1 or COMP2
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// changes, not both, so alternate reading bits from them. We get 1 INM bit of output
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// per byte read. Feed bits from the INM to the health checker. Return the expected
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// bits of entropy.
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static uint32_t extractBytes(uint8_t *bytes, uint8_t *inBuf) {
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inmClearEntropyLevel();
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//printf("New batch\n");
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uint32_t i;
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for(i = 0u; i < BUFLEN/8u; i++) {
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uint32_t j;
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uint8_t byte = 0u;
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for(j = 0u; j < 8u; j++) {
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//printf("%x ", inBuf[i*8u + j] & ~MASK);
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uint8_t val = inBuf[i*8u + j];
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uint8_t evenBit = (val >> COMP2) & 1u;
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uint8_t oddBit = (val >> COMP1) & 1u;
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bool even = j & 1u; // Use the even bit if j is odd
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uint8_t bit = even? evenBit : oddBit;
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byte = (byte << 1u) | bit;
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// This is a good place to feed the bit from the INM to the health checker.
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//printf("Address: %u, adding evenBit:%u oddBit:%u even:%u\n", addr, evenBit, oddBit, even);
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if(!inmHealthCheckAddBit(evenBit, oddBit, even)) {
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fputs("Health check of Infinite Noise Multiplier failed!\n", stderr);
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exit(1);
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}
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}
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//printf("extracted byte:%x\n", byte);
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bytes[i] = byte;
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}
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return inmGetEntropyLevel();
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}
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// Write the bytes to either stdout, or /dev/random.
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static void outputBytes(uint8_t *bytes, uint32_t length, uint32_t entropy, bool writeDevRandom) {
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if(!writeDevRandom) {
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if(fwrite(bytes, 1, length, stdout) != length) {
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fputs("Unable to write output from Infinite Noise Multiplier\n", stderr);
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exit(1);
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}
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} else {
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inmWaitForPoolToHaveRoom();
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inmWriteEntropyToPool(bytes, length, entropy);
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}
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}
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// Whiten the output, if requested, with a Keccak sponge. Output bytes only if the health
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// checker says it's OK. Using outputMultiplier > 1 is a nice way to generate a lot more
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// cryptographically secure pseudo-random data than the INM generates. If
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// outputMultiplier is 0, we output only as many bits as we measure in entropy.
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// This allows a user to generate hundreds of MiB per second if needed, for use
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// as cryptogrpahic keys.
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static uint32_t processBytes(uint8_t *keccakState, uint8_t *bytes, uint32_t entropy, bool raw,
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bool writeDevRandom, uint32_t outputMultiplier) {
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//Use the lower of the measured entropy and the provable lower bound on
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//average entropy.
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if(entropy > inmExpectedEntropyPerBit*BUFLEN/INM_ACCURACY) {
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entropy = inmExpectedEntropyPerBit*BUFLEN/INM_ACCURACY;
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}
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if(raw) {
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// In raw mode, we just output raw data from the INM.
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outputBytes(bytes, BUFLEN/8u, entropy, writeDevRandom);
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return BUFLEN/8u;
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}
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// Note that BUFLEN has to be less than 1600 by enough to make the sponge secure,
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// since outputing all 1600 bits would tell an attacker the Keccak state, allowing
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// him to predict any further output, when outputMultiplier > 1, until the next call
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// to processBytes. All 512 bits are absorbed before sqeezing data out to insure that
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// we instantly recover (reseed) from a state compromise, which is when an attacker
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// gets a snapshot of the keccak state. BUFLEN must be a multiple of 64, since
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// Keccak-1600 uses 64-bit "lanes".
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KeccakAbsorb(keccakState, bytes, BUFLEN/64u);
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uint8_t dataOut[16u*8u];
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if(outputMultiplier == 0u) {
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// Output all the bytes of entropy we have
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KeccakExtract(keccakState, dataOut, (entropy + 63u)/64u);
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outputBytes(dataOut, entropy/8u, entropy & 0x7u, writeDevRandom);
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return entropy/8u;
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}
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// Output 256*outputMultipler bytes.
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uint32_t numBits = outputMultiplier*256u;
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uint32_t bytesWritten = 0u;
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while(numBits > 0u) {
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// Write up to 1024 bits at a time.
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uint32_t bytesToWrite = 1024u/8u;
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if(bytesToWrite > numBits/8u) {
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bytesToWrite = numBits/8u;
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}
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KeccakExtract(keccakState, dataOut, bytesToWrite/8u);
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uint32_t entropyThisTime = entropy;
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if(entropyThisTime > 8u*bytesToWrite) {
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entropyThisTime = 8u*bytesToWrite;
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}
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outputBytes(dataOut, bytesToWrite, entropyThisTime, writeDevRandom);
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bytesWritten += bytesToWrite;
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numBits -= bytesToWrite*8u;
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entropy -= entropyThisTime;
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if(numBits > 0u) {
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KeccakPermutation(keccakState);
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}
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}
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if(bytesWritten != outputMultiplier*(256u/8u)) {
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fprintf(stderr, "Internal error outputing bytes\n");
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exit(1);
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}
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return bytesWritten;
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}
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// Initialize the Infinite Noise Multiplier USB ineterface.
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static bool initializeUSB(struct ftdi_context *ftdic, char **message) {
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*message = NULL;
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// Initialize FTDI context
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ftdi_init(ftdic);
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// Open FTDI device based on FT240X vendor & product IDs
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if(ftdi_usb_open(ftdic, 0x0403, 0x6015) < 0) {
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if(!isSuperUser()) {
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*message = "Can't find Infinite Noise Multiplier. Try running as super user?\n";
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} else {
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*message = "Can't find Infinite Noise Multiplier\n";
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}
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return false;
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}
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// Set high baud rate
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int rc = ftdi_set_baudrate(ftdic, 30000);
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if(rc == -1) {
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*message = "Invalid baud rate\n";
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return false;
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} else if(rc == -2) {
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*message = "Setting baud rate failed\n";
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return false;
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} else if(rc == -3) {
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*message = "Infinite Noise Multiplier unavailable\n";
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return false;
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}
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// Enable syncrhonous bitbang mode
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rc = ftdi_set_bitmode(ftdic, MASK, BITMODE_SYNCBB);
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if(rc == -1) {
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*message = "Can't enable bit-bang mode\n";
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return false;
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} else if(rc == -2) {
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*message = "Infinite Noise Multiplier unavailable\n";
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return false;
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}
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// Just test to see that we can write and read.
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uint8_t buf[64u] = {0u,};
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if(ftdi_write_data(ftdic, buf, 64) != 64) {
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*message = "USB write failed\n";
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return false;
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}
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if(ftdi_read_data(ftdic, buf, 64) != 64) {
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*message = "USB read failed\n";
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return false;
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}
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return true;
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}
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// Return the differnece in the times as a double in microseconds.
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static double diffTime(struct timespec *start, struct timespec *end) {
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uint32_t seconds = end->tv_sec - start->tv_sec;
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int32_t nanoseconds = end->tv_nsec - start->tv_nsec;
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return seconds*1.0e6 + nanoseconds/1000.0;
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}
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int main(int argc, char **argv)
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{
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struct ftdi_context ftdic;
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bool raw = false;
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bool debug = false;
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bool writeDevRandom = false;
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bool noOutput = false;
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uint32_t outputMultiplier = 0u; // We output all the entropy when outputMultiplier == 0
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int xArg;
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bool multiplierAssigned = false;
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bool pidFile = false;
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char *pidFileName = NULL;
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bool runDaemon = false;
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// Process arguments
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for(xArg = 1; xArg < argc; xArg++) {
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if(!strcmp(argv[xArg], "--raw")) {
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raw = true;
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} else if(!strcmp(argv[xArg], "--debug")) {
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debug = true;
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} else if(!strcmp(argv[xArg], "--dev-random")) {
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writeDevRandom = true;
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} else if(!strcmp(argv[xArg], "--no-output")) {
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noOutput = true;
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} else if(!strcmp(argv[xArg], "--multiplier") && xArg+1 < argc) {
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xArg++;
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multiplierAssigned = true;
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int tmpOutputMult = atoi(argv[xArg]);
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if(tmpOutputMult < 0) {
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fputs("Multiplier must be >= 0\n", stderr);
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return 1;
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}
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outputMultiplier = tmpOutputMult;
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} else if(!strcmp(argv[xArg], "--pidfile")) {
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xArg++;
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pidFileName = argv[xArg];
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pidFile = true;
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if(pidFileName == NULL || !strcmp("",pidFileName)) {
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fputs("--pidfile without file name\n", stderr);
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return 1;
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}
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} else if(!strcmp(argv[xArg], "--daemon")) {
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runDaemon = true;
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} else {
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fputs("Usage: infnoise [options]\n"
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"Options are:\n"
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" --debug - turn on some debug output\n"
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" --dev-random - write entropy to /dev/random instead of stdout\n"
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" --raw - do not whiten the output\n"
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" --multiplier <value> - write 256 bits * value for each 512 bits written to\n"
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" the Keccak sponge. Default of 0 means write all the entropy.\n"
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" --no-output - do not write random output data\n"
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" --pidfile <file> - write process ID to file\n"
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" --daemon - run in the background\n", stderr);
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return 1;
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}
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}
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if(!multiplierAssigned && writeDevRandom) {
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outputMultiplier = 2u; // Don't throw away entropy when writing to /dev/random unless told to do so
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}
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// Optionally run in the background and optionally write a PID-file
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startDaemon(runDaemon, pidFile, pidFileName);
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if(writeDevRandom) {
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inmWriteEntropyStart(BUFLEN/8u, debug);
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}
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if(!inmHealthCheckStart(PREDICTION_BITS, DESIGN_K, debug)) {
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fputs("Can't intialize health checker\n", stderr);
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return 1;
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}
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KeccakInitialize();
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uint8_t keccakState[KeccakPermutationSizeInBytes];
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KeccakInitializeState(keccakState);
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char *message;
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if(!initializeUSB(&ftdic, &message)) {
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// Sometimes have to do it twice - not sure why
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if(!initializeUSB(&ftdic, &message)) {
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fputs(message, stderr);
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return 1;
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}
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}
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// Endless loop: set SW1EN and SW2EN alternately
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uint32_t i;
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uint8_t outBuf[BUFLEN], inBuf[BUFLEN];
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for(i = 0u; i < BUFLEN; i++) {
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// Alternate Ph1 and Ph2
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outBuf[i] = i & 1? (1 << SWEN2) : (1 << SWEN1);
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}
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uint64_t totalBytesWritten = 0u;
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while(true) {
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struct timespec start;
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clock_gettime(CLOCK_REALTIME, &start);
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if(ftdi_write_data(&ftdic, outBuf, BUFLEN) != BUFLEN) {
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fputs("USB write failed\n", stderr);
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return 1;
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}
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if(ftdi_read_data(&ftdic, inBuf, BUFLEN) != BUFLEN) {
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fputs("USB read failed\n", stderr);
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return 1;
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}
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struct timespec end;
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clock_gettime(CLOCK_REALTIME, &end);
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uint32_t us = diffTime(&start, &end);
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//printf("diffTime:%u us\n", us);
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if(us <= MAX_MICROSEC_FOR_SAMPLES) {
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uint8_t bytes[BUFLEN/8u];
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uint32_t entropy = extractBytes(bytes, inBuf);
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if(!noOutput && inmHealthCheckOkToUseData() && inmEntropyOnTarget(entropy, BUFLEN)) {
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uint64_t prevTotalBytesWritten = totalBytesWritten;
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totalBytesWritten += processBytes(keccakState, bytes, entropy, raw, writeDevRandom, outputMultiplier);
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if(debug && (1u << 20u)*(totalBytesWritten/(1u << 20u)) > (1u << 20u)*(prevTotalBytesWritten/(1u << 20u))) {
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fprintf(stderr, "Output %lu bytes\n", (unsigned long)totalBytesWritten);
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}
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}
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}
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}
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return 0;
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}
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