hedera.c

#include "hedera.h"

#include <cx.h>
#include <os.h>
#include <string.h>

#include "crypto_helpers.h"
#include "utils.h"
#include <stddef.h>
#include <stdbool.h>

// Constructs the fixed Hedera derivation path: m/44'/3030'/0'/0'/index'
// Used for transaction signing and public key operations
// Only the index parameter varies; all other path components are hardcoded
static void hedera_set_path(uint32_t index, uint32_t path[static 5]) {
    path[0] = PATH_ZERO;   // 44'
    path[1] = PATH_ONE;    // 3030'
    path[2] = PATH_TWO;    // 0'
    path[3] = PATH_THREE;  // 0'
    path[4] = PATH_FOUR;   // index'
}

bool hedera_get_pubkey(uint32_t index, uint8_t raw_pubkey[static RAW_PUBKEY_SIZE]) {
    uint32_t path[5];

    hedera_set_path(index, path);

    if (CX_OK != bip32_derive_with_seed_get_pubkey_256(
                     HDW_ED25519_SLIP10, CX_CURVE_Ed25519, path, 5, raw_pubkey,
                     NULL, CX_SHA512, NULL, 0)) {
        return false;
    }

    return true;
}

bool hedera_sign(uint32_t index, const uint8_t* tx, uint8_t tx_len,
                 /* out */ uint8_t* result, /* out */ size_t* sig_len_out) {
    uint32_t path[5];
    size_t sig_len = 64;

    hedera_set_path(index, path);

    if (CX_OK != bip32_derive_with_seed_eddsa_sign_hash_256(
                     HDW_ED25519_SLIP10, CX_CURVE_Ed25519, path, 5, CX_SHA512,
                     tx,     // hash (really message)
                     tx_len, // hash length (really message length)
                     result, // signature
                     &sig_len, NULL, 0)) {
        return false;
    }
    if (sig_len_out) *sig_len_out = sig_len;
    return true;
}