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feat: add function to get and hash tx.data
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@keiff3r
keiff3r committed Sep 12, 2024
1 parent 63a1fa5 commit 7b02581
Showing 1 changed file with 78 additions and 56 deletions.
134 changes: 78 additions & 56 deletions src/handler/withdraw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,10 @@
#define AMOUNT_SIZE_IN_BYTES 8
#define AMOUNT_SIZE_IN_CHARS 16 + 10

// Constants for hash computation

////////////////////////

static unsigned char const BSM_SIGN_MAGIC[] = {'\x18', 'B', 'i', 't', 'c', 'o', 'i', 'n', ' ',

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Unused static variable Note

Static variable BSM_SIGN_MAGIC is never read.
'S', 'i', 'g', 'n', 'e', 'd', ' ', 'M', 'e',
's', 's', 'a', 'g', 'e', ':', '\n'};
Expand Down Expand Up @@ -144,32 +148,14 @@ void add_leading_zeroes(uint8_t* dest_buffer,
memcpy(dest_buffer + buffer_offset, src_buffer, src_size);
}

/**
* @brief Fetches a chunk of data from a Merkle tree and adds it to a hash.
*
* This function retrieves a specific chunk of data from a Merkle tree using the provided
* dispatcher context and Merkle root. The retrieved chunk is then added to a hash buffer
* at a specified offset and hashed using the provided SHA-3 context.
*
* @param dc Pointer to the dispatcher context. (in)
* @param data_merkle_root Pointer to the Merkle root of the data. (in)
* @param n_chunks Total number of chunks in the Merkle tree. (in)
* @param chunk_index Index of the chunk to fetch. (in)
* @param hash Pointer to the SHA-3 hash context. (in/out)
* @param buffer_offset Offset within the hash buffer where the chunk data should be added. (in)
* @param chunk_offset Offset within the chunk data to start copying from. (in)
* @param chunk_data_size Size of the chunk data to copy. (in)
*
* @return void
*/
void fetch_and_add_chunk_to_hash(dispatcher_context_t* dc,
uint8_t* data_merkle_root,
size_t n_chunks,
cx_sha3_t* hash_context,
size_t chunk_index,
cx_sha3_t* hash,
size_t buffer_offset,
size_t chunk_offset,
size_t chunk_data_size) {
size_t chunk_data_size,
bool abi_encode) {
uint8_t data_chunk[CHUNK_SIZE_IN_BYTES];
int current_chunk_len = call_get_merkle_leaf_element(dc,
data_merkle_root,
Expand All @@ -179,34 +165,70 @@ void fetch_and_add_chunk_to_hash(dispatcher_context_t* dc,
CHUNK_SIZE_IN_BYTES);
if (current_chunk_len < 0) {
SEND_SW(dc, SW_WRONG_DATA_LENGTH);
ui_post_processing_confirm_withdraw(dc, false);

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has no external side effects).
return;
}
size_t input_buffer_size;
uint8_t input_buffer[32];

if (abi_encode) {
input_buffer_size = 32;
add_leading_zeroes(input_buffer,
sizeof(input_buffer),
data_chunk + chunk_offset,
chunk_data_size);
} else {
input_buffer_size = chunk_data_size;
memcpy(input_buffer, data_chunk + chunk_offset, input_buffer_size);
}
uint8_t hash_buffer[32];
add_leading_zeroes(hash_buffer,
sizeof(hash_buffer),
data_chunk + chunk_offset,
chunk_data_size);
CX_THROW(cx_hash_no_throw((cx_hash_t*) hash,
0, // mode
hash_buffer, // input
sizeof(hash_buffer), // input length
NULL, // output
0)); // output length
CX_THROW(cx_hash_no_throw((cx_hash_t*) hash_context,
0, // mode
input_buffer, // input data
input_buffer_size, // input length
NULL, // output (intermediate)
0)); // no output yet
}

void compute_hash(dispatcher_context_t* dc,
uint8_t* data_merkle_root,
size_t n_chunks,
cx_sha3_t* hash) {
CX_THROW(cx_keccak_init_no_throw(hash, 256));

fetch_and_add_chunk_to_hash(dc,
data_merkle_root,
n_chunks,
0,
hash,
12,
0,
ADDRESS_SIZE_IN_BYTES);
void fetch_and_hash_tx_data(dispatcher_context_t* dc,
uint8_t* data_merkle_root,
size_t n_chunks,
cx_sha3_t* hash_context,
uint8_t* output_buffer) {
// Fetch and add the first 4 bytes of the tx.data to the hash
fetch_and_add_chunk_to_hash(dc, data_merkle_root, n_chunks, hash_context, 4, 0, 4, false);
// Fetch and add the other value is tx.data to the hash
for (size_t i = 5; i < n_chunks; i++) {
// Fetch and add data[32] to the hash
fetch_and_add_chunk_to_hash(dc, data_merkle_root, n_chunks, hash_context, i, 0, 32, false);
// Fetch and add data[32] to the hash
fetch_and_add_chunk_to_hash(dc, data_merkle_root, n_chunks, hash_context, i, 32, 32, false);
}
// Finalize the hash and store the result in output_hash
CX_THROW(cx_hash_no_throw((cx_hash_t*) hash_context,
CX_LAST, // final block mode
NULL, // no more input
0, // no more input length
output_buffer, // output hash buffer
32)); // output hash length (32 bytes)
}

void compute_tx_hash(dispatcher_context_t* dc,
uint8_t* data_merkle_root,
size_t n_chunks,
u_int8_t output_buffer[32]) {
cx_sha3_t hash_context;

// Initialize the SHA-3 context for Keccak-256 (256-bit output)
CX_THROW(cx_keccak_init_no_throw(&hash_context, 256));
u_int8_t keccak_of_tx_data[32];
// Compute keccak256 hash of the tx_data_data
fetch_and_hash_tx_data(dc, data_merkle_root, n_chunks, &hash_context, keccak_of_tx_data);

// Abi.encode 1
// Abi.encode 2
// Compute keccak256 hash of abi.encode 2
// Abi.encodePacked
// Keccak256 hash of abi.encodePacked
}

void handler_withdraw(dispatcher_context_t* dc, uint8_t protocol_version) {
Expand Down Expand Up @@ -238,22 +260,22 @@ void handler_withdraw(dispatcher_context_t* dc, uint8_t protocol_version) {
}

#ifndef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
// ui_pre_processing_message();
if (!display_data_content_and_confirm(dc, data_merkle_root, n_chunks)) {
SEND_SW(dc, SW_DENY);
ui_post_processing_confirm_withdraw(dc, false);
return;
}
// // ui_pre_processing_message();
// if (!display_data_content_and_confirm(dc, data_merkle_root, n_chunks)) {
// SEND_SW(dc, SW_DENY);
// ui_post_processing_confirm_withdraw(dc, false);
// return;
// }

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#endif
// COMPUTE THE HASH THAT WE WILL SIGN
cx_sha3_t hash;
compute_hash(dc, data_merkle_root, n_chunks, &hash);
uint8_t tx_hash[32];
compute_tx_hash(dc, data_merkle_root, n_chunks, tx_hash);
// SIGN MESSAGE (the message is the hash previously computed)
uint8_t sig[MAX_DER_SIG_LEN];

// Send the response to the JS Library
uint8_t sig[65];
SEND_RESPONSE(dc, sig, sizeof(sig), SW_OK);

ui_post_processing_confirm_withdraw(dc, true);

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return;
}

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