hedera.c

#include <os.h>
#include "globals.h"
#include "printf.h"
#include "hedera.h"

void hedera_derive_keypair(
    uint32_t index,
    /* out */ cx_ecfp_private_key_t* secret, 
    /* out */ cx_ecfp_public_key_t* public
) {
    static uint8_t seed[32];
    static uint32_t path[5];
    static cx_ecfp_private_key_t pk;

    path[0] = 44 | 0x80000000;
    path[1] = 3030 | 0x80000000;
    path[2] = index | 0x80000000;
    path[3] = 0x80000000;
    path[4] = 0x80000000;

    os_perso_derive_node_bip32_seed_key(
        HDW_ED25519_SLIP10, 
        CX_CURVE_Ed25519, 
        path, 
        5, 
        seed, 
        NULL, 
        NULL, 
        0
    );

    cx_ecfp_init_private_key(
        CX_CURVE_Ed25519, 
        seed, 
        sizeof(seed), 
        &pk
    );

    if (public) {
        cx_ecfp_init_public_key(
            CX_CURVE_Ed25519, 
            NULL, 
            0, 
            public
        );
        cx_ecfp_generate_pair(
            CX_CURVE_Ed25519, 
            public, 
            &pk, 
            1
        );
    }

    if (secret) {
        *secret = pk;
    }

    os_memset(seed, 0, sizeof(seed));
    os_memset(&pk, 0, sizeof(pk));
}

void hedera_sign(
    uint32_t index,
    const uint8_t* tx,
    uint8_t tx_len,
    /* out */ uint8_t* result
) {
    static cx_ecfp_private_key_t pk;

    // Get Keys
    hedera_derive_keypair(index, &pk, NULL);

    // Sign Transaction
    // <cx.h> 2283
    // Claims to want Hashes, but other apps use the message itself
    // and complain that the documentation is wrong
    cx_eddsa_sign(
        &pk,                             // private key
        0,                               // mode (UNSUPPORTED)
        CX_SHA512,                       // hashID
        tx,                              // hash (really message)
        tx_len,                          // hash length (really message length)
        NULL,                            // context (UNUSED)
        0,                               // context length (0)
        result,                          // signature
        64,                              // signature length
        NULL                             // info
    );

    // Clear private key
    os_memset(&pk, 0, sizeof(pk));
}

char* hedera_format_tinybar(uint64_t tinybar) {
    static char buf[HBAR_BUF_SIZE];
    static uint64_t hbar;
    static uint64_t hbar_f;
    static int cnt;
    
    os_memset(buf, '\0', HBAR_BUF_SIZE);
    cnt = 0;
    
    hbar = tinybar / HBAR;
    hbar_f = tinybar % HBAR; 

    cnt = hedera_snprintf(buf, HBAR_BUF_SIZE, "%llu", hbar);

    if (hbar_f != 0) {
        cnt += hedera_snprintf(buf + cnt, HBAR_BUF_SIZE - cnt, ".%.8llu", hbar_f);
    }

    buf[cnt] = '\0';
    return buf;
}