main.ino

#include "crypto_aead.h"
#include "api.h"
#include "uartp.h"

#define MAX_BYTES 100

//#define DEBUG
#define CRYPTO_BUSY 12

uint8_t npub[CRYPTO_NPUBBYTES];
uint8_t nsec[CRYPTO_NSECBYTES];
uint8_t k[CRYPTO_KEYBYTES];
uint8_t ad[MAX_BYTES];
unsigned long long int adlen;
uint8_t m[MAX_BYTES];
unsigned long long int mlen;
uint8_t c[MAX_BYTES];
unsigned long long int clen;

#ifdef __cplusplus
extern "C" {
#endif

void uart_write(uint8_t x) {
    Serial.write((uint8_t) (x));
}

uint8_t uart_read() {
    int r;
    do {
        r = Serial.read();
    } while (r == -1);
    return (uint8_t) (0xff & r);
}

#ifdef __cplusplus
}
#endif

#ifdef DEBUG
#define DEBUG_BUF_LEN 80
int dbg_printf(const char *format, ...) {
    char printbuf[DEBUG_BUF_LEN+2];

    va_list vargs;
    va_start(vargs, format);
    int r = vsnprintf(printbuf+1, DEBUG_BUF_LEN, format, vargs);
    va_end(vargs);

    if (r < 0) {
        memcpy(printbuf+1, "DEBUG ERROR\r\n", 13);
        r = 13;
    }

    r = r > DEBUG_BUF_LEN ? DEBUG_BUF_LEN : r;
    printbuf[0] = 0xde;  // Debug messages should start with "\xde"
    uartp_send(printbuf, r+1);
    return r;
}
#else
#define dbg_printf(...) (0)
#endif

void assert(bool b) {
    if (b)
        return;
    dbg_printf("Assertion failed\r\n");
    for(;;)
        yield();
}

void setup() {
    Serial.begin(115200);
    pinMode(CRYPTO_BUSY, OUTPUT);
    digitalWrite(CRYPTO_BUSY, HIGH);
    delay(100);
    Serial.print("Hello, World!");
}


void loop() {
    static uint8_t buf[256];
    int res;
    uint16_t len = uartp_recv(buf, 255);
    uint8_t action = buf[0];
    if (len == 0 || len > 255)
        return;

    uint16_t l = len - 1;
    uint16_t rl = 0;
    uint8_t *var = buf+1;
    switch (action) {
        case 'm': assert(l <= MAX_BYTES);        memcpy(m,    var, l); mlen = l; break;
        case 'c': assert(l <= MAX_BYTES);        memcpy(c,    var, l); clen = l; break;
        case 'a': assert(l <= MAX_BYTES);        memcpy(ad,   var, l); adlen = l; break;
        case 'k': assert(l == CRYPTO_KEYBYTES);  memcpy(k,    var, l); break;
        case 'p': assert(l == CRYPTO_NPUBBYTES); memcpy(npub, var, l); break;
        case 's': assert(l == CRYPTO_NSECBYTES); memcpy(nsec, var, l); break;
        case 'e':
			noInterrupts();
			asm("nop");
            digitalWrite(CRYPTO_BUSY, LOW);
            res = crypto_aead_encrypt(c, &clen, m, mlen, ad, adlen, nsec, npub, k);
            digitalWrite(CRYPTO_BUSY, HIGH);
			asm("nop");
			interrupts();
            break;
        case 'd':
			noInterrupts();
			asm("nop");
            digitalWrite(CRYPTO_BUSY, LOW);
            res = crypto_aead_decrypt(m, &mlen, nsec, c, clen, ad, adlen, npub, k);
            digitalWrite(CRYPTO_BUSY, HIGH);
			asm("nop");
			interrupts();
            break;
        case'M': var = m;    rl = mlen; break;
        case'C': var = c;    rl = clen; break;
        case'A': var = ad;   rl = adlen; break;
        case'K': var = k;    rl = CRYPTO_KEYBYTES; break;
        case'P': var = npub; rl = CRYPTO_NPUBBYTES; break;
        case'S': var = nsec; rl = CRYPTO_NSECBYTES; break;
        default:
            dbg_printf("Unknown command\r\n");
            assert(false);
    }
    buf[0] = action;
    memcpy(buf+1, var, rl);
    uartp_send(buf, rl+1);
}