Signature proving payment to destination by only revealing key derivation, not the actual tx secret key

This commit is contained in:
stoffu 2017-03-30 08:22:16 +09:00
parent 038e6cd33e
commit c9e0e944e9
No known key found for this signature in database
GPG Key ID: 41DAB8343A9EC012
4 changed files with 359 additions and 15 deletions

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@ -197,6 +197,13 @@ namespace crypto {
ec_point comm; ec_point comm;
}; };
struct s_comm_2 {
hash msg;
ec_point D;
ec_point X;
ec_point Y;
};
void crypto_ops::generate_signature(const hash &prefix_hash, const public_key &pub, const secret_key &sec, signature &sig) { void crypto_ops::generate_signature(const hash &prefix_hash, const public_key &pub, const secret_key &sec, signature &sig) {
boost::lock_guard<boost::mutex> lock(random_lock); boost::lock_guard<boost::mutex> lock(random_lock);
ge_p3 tmp3; ge_p3 tmp3;
@ -242,6 +249,124 @@ namespace crypto {
return sc_isnonzero(&c) == 0; return sc_isnonzero(&c) == 0;
} }
void crypto_ops::generate_tx_proof(const hash &prefix_hash, const public_key &R, const public_key &A, const public_key &D, const secret_key &r, signature &sig) {
// sanity check
ge_p3 R_p3;
ge_p3 A_p3;
ge_p3 D_p3;
if (ge_frombytes_vartime(&R_p3, &R) != 0) throw std::runtime_error("tx pubkey is invalid");
if (ge_frombytes_vartime(&A_p3, &A) != 0) throw std::runtime_error("recipient view pubkey is invalid");
if (ge_frombytes_vartime(&D_p3, &D) != 0) throw std::runtime_error("key derivation is invalid");
#if !defined(NDEBUG)
{
assert(sc_check(&r) == 0);
// check R == r*G
ge_p3 dbg_R_p3;
ge_scalarmult_base(&dbg_R_p3, &r);
public_key dbg_R;
ge_p3_tobytes(&dbg_R, &dbg_R_p3);
assert(R == dbg_R);
// check D == r*A
ge_p2 dbg_D_p2;
ge_scalarmult(&dbg_D_p2, &r, &A_p3);
public_key dbg_D;
ge_tobytes(&dbg_D, &dbg_D_p2);
assert(D == dbg_D);
}
#endif
// pick random k
ec_scalar k;
random_scalar(k);
// compute X = k*G
ge_p3 X_p3;
ge_scalarmult_base(&X_p3, &k);
// compute Y = k*A
ge_p2 Y_p2;
ge_scalarmult(&Y_p2, &k, &A_p3);
// sig.c = Hs(Msg || D || X || Y)
s_comm_2 buf;
buf.msg = prefix_hash;
buf.D = D;
ge_p3_tobytes(&buf.X, &X_p3);
ge_tobytes(&buf.Y, &Y_p2);
hash_to_scalar(&buf, sizeof(s_comm_2), sig.c);
// sig.r = k - sig.c*r
sc_mulsub(&sig.r, &sig.c, &r, &k);
}
bool crypto_ops::check_tx_proof(const hash &prefix_hash, const public_key &R, const public_key &A, const public_key &D, const signature &sig) {
// sanity check
ge_p3 R_p3;
ge_p3 A_p3;
ge_p3 D_p3;
if (ge_frombytes_vartime(&R_p3, &R) != 0) return false;
if (ge_frombytes_vartime(&A_p3, &A) != 0) return false;
if (ge_frombytes_vartime(&D_p3, &D) != 0) return false;
if (sc_check(&sig.c) != 0 || sc_check(&sig.r) != 0) return false;
// compute sig.c*R
ge_p2 cR_p2;
ge_scalarmult(&cR_p2, &sig.c, &R_p3);
// compute sig.r*G
ge_p3 rG_p3;
ge_scalarmult_base(&rG_p3, &sig.r);
// compute sig.c*D
ge_p2 cD_p2;
ge_scalarmult(&cD_p2, &sig.c, &D_p3);
// compute sig.r*A
ge_p2 rA_p2;
ge_scalarmult(&rA_p2, &sig.r, &A_p3);
// compute X = sig.c*R + sig.r*G
public_key cR;
ge_tobytes(&cR, &cR_p2);
ge_p3 cR_p3;
if (ge_frombytes_vartime(&cR_p3, &cR) != 0) return false;
ge_cached rG_cached;
ge_p3_to_cached(&rG_cached, &rG_p3);
ge_p1p1 X_p1p1;
ge_add(&X_p1p1, &cR_p3, &rG_cached);
ge_p2 X_p2;
ge_p1p1_to_p2(&X_p2, &X_p1p1);
// compute Y = sig.c*D + sig.r*A
public_key cD;
public_key rA;
ge_tobytes(&cD, &cD_p2);
ge_tobytes(&rA, &rA_p2);
ge_p3 cD_p3;
ge_p3 rA_p3;
if (ge_frombytes_vartime(&cD_p3, &cD) != 0) return false;
if (ge_frombytes_vartime(&rA_p3, &rA) != 0) return false;
ge_cached rA_cached;
ge_p3_to_cached(&rA_cached, &rA_p3);
ge_p1p1 Y_p1p1;
ge_add(&Y_p1p1, &cD_p3, &rA_cached);
ge_p2 Y_p2;
ge_p1p1_to_p2(&Y_p2, &Y_p1p1);
// compute c2 = Hs(Msg || D || X || Y)
s_comm_2 buf;
buf.msg = prefix_hash;
buf.D = D;
ge_tobytes(&buf.X, &X_p2);
ge_tobytes(&buf.Y, &Y_p2);
ec_scalar c2;
hash_to_scalar(&buf, sizeof(s_comm_2), c2);
// test if c2 == sig.c
sc_sub(&c2, &c2, &sig.c);
return sc_isnonzero(&c2) == 0;
}
static void hash_to_ec(const public_key &key, ge_p3 &res) { static void hash_to_ec(const public_key &key, ge_p3 &res) {
hash h; hash h;
ge_p2 point; ge_p2 point;

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@ -123,6 +123,10 @@ namespace crypto {
friend void generate_signature(const hash &, const public_key &, const secret_key &, signature &); friend void generate_signature(const hash &, const public_key &, const secret_key &, signature &);
static bool check_signature(const hash &, const public_key &, const signature &); static bool check_signature(const hash &, const public_key &, const signature &);
friend bool check_signature(const hash &, const public_key &, const signature &); friend bool check_signature(const hash &, const public_key &, const signature &);
static void generate_tx_proof(const hash &, const public_key &, const public_key &, const public_key &, const secret_key &, signature &);
friend void generate_tx_proof(const hash &, const public_key &, const public_key &, const public_key &, const secret_key &, signature &);
static bool check_tx_proof(const hash &, const public_key &, const public_key &, const public_key &, const signature &);
friend bool check_tx_proof(const hash &, const public_key &, const public_key &, const public_key &, const signature &);
static void generate_key_image(const public_key &, const secret_key &, key_image &); static void generate_key_image(const public_key &, const secret_key &, key_image &);
friend void generate_key_image(const public_key &, const secret_key &, key_image &); friend void generate_key_image(const public_key &, const secret_key &, key_image &);
static void generate_ring_signature(const hash &, const key_image &, static void generate_ring_signature(const hash &, const key_image &,
@ -200,6 +204,16 @@ namespace crypto {
return crypto_ops::check_signature(prefix_hash, pub, sig); return crypto_ops::check_signature(prefix_hash, pub, sig);
} }
/* Generation and checking of a tx proof; given a tx pubkey R, the recipient's view pubkey A, and the key
* derivation D, the signature proves the knowledge of the tx secret key r such that R=r*G and D=r*A
*/
inline void generate_tx_proof(const hash &prefix_hash, const public_key &R, const public_key &A, const public_key &D, const secret_key &r, signature &sig) {
crypto_ops::generate_tx_proof(prefix_hash, R, A, D, r, sig);
}
inline bool check_tx_proof(const hash &prefix_hash, const public_key &R, const public_key &A, const public_key &D, const signature &sig) {
return crypto_ops::check_tx_proof(prefix_hash, R, A, D, sig);
}
/* To send money to a key: /* To send money to a key:
* * The sender generates an ephemeral key and includes it in transaction output. * * The sender generates an ephemeral key and includes it in transaction output.
* * To spend the money, the receiver generates a key image from it. * * To spend the money, the receiver generates a key image from it.

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@ -47,6 +47,7 @@
#include "common/command_line.h" #include "common/command_line.h"
#include "common/util.h" #include "common/util.h"
#include "common/dns_utils.h" #include "common/dns_utils.h"
#include "common/base58.h"
#include "p2p/net_node.h" #include "p2p/net_node.h"
#include "cryptonote_protocol/cryptonote_protocol_handler.h" #include "cryptonote_protocol/cryptonote_protocol_handler.h"
#include "simplewallet.h" #include "simplewallet.h"
@ -714,6 +715,8 @@ simple_wallet::simple_wallet()
m_cmd_binder.set_handler("rescan_spent", boost::bind(&simple_wallet::rescan_spent, this, _1), tr("Rescan blockchain for spent outputs")); m_cmd_binder.set_handler("rescan_spent", boost::bind(&simple_wallet::rescan_spent, this, _1), tr("Rescan blockchain for spent outputs"));
m_cmd_binder.set_handler("get_tx_key", boost::bind(&simple_wallet::get_tx_key, this, _1), tr("Get transaction key (r) for a given <txid>")); m_cmd_binder.set_handler("get_tx_key", boost::bind(&simple_wallet::get_tx_key, this, _1), tr("Get transaction key (r) for a given <txid>"));
m_cmd_binder.set_handler("check_tx_key", boost::bind(&simple_wallet::check_tx_key, this, _1), tr("Check amount going to <address> in <txid>")); m_cmd_binder.set_handler("check_tx_key", boost::bind(&simple_wallet::check_tx_key, this, _1), tr("Check amount going to <address> in <txid>"));
m_cmd_binder.set_handler("get_tx_proof", boost::bind(&simple_wallet::get_tx_proof, this, _1), tr("Generate a signature to prove payment to <address> in <txid> using the transaction secret key (r) without revealing it"));
m_cmd_binder.set_handler("check_tx_proof", boost::bind(&simple_wallet::check_tx_proof, this, _1), tr("Check tx proof for payment going to <address> in <txid>"));
m_cmd_binder.set_handler("show_transfers", boost::bind(&simple_wallet::show_transfers, this, _1), tr("show_transfers [in|out|pending|failed|pool] [<min_height> [<max_height>]] - Show incoming/outgoing transfers within an optional height range")); m_cmd_binder.set_handler("show_transfers", boost::bind(&simple_wallet::show_transfers, this, _1), tr("show_transfers [in|out|pending|failed|pool] [<min_height> [<max_height>]] - Show incoming/outgoing transfers within an optional height range"));
m_cmd_binder.set_handler("unspent_outputs", boost::bind(&simple_wallet::unspent_outputs, this, _1), tr("unspent_outputs [<min_amount> <max_amount>] - Show unspent outputs within an optional amount range)")); m_cmd_binder.set_handler("unspent_outputs", boost::bind(&simple_wallet::unspent_outputs, this, _1), tr("unspent_outputs [<min_amount> <max_amount>] - Show unspent outputs within an optional amount range)"));
m_cmd_binder.set_handler("rescan_bc", boost::bind(&simple_wallet::rescan_blockchain, this, _1), tr("Rescan blockchain from scratch")); m_cmd_binder.set_handler("rescan_bc", boost::bind(&simple_wallet::rescan_blockchain, this, _1), tr("Rescan blockchain from scratch"));
@ -3232,6 +3235,85 @@ bool simple_wallet::get_tx_key(const std::vector<std::string> &args_)
} }
} }
//---------------------------------------------------------------------------------------------------- //----------------------------------------------------------------------------------------------------
bool simple_wallet::get_tx_proof(const std::vector<std::string> &args)
{
if(args.size() != 2 && args.size() != 3) {
fail_msg_writer() << tr("usage: get_tx_proof <txid> <dest_address> [<tx_key>]");
return true;
}
if (m_wallet->ask_password() && !get_and_verify_password()) { return true; }
cryptonote::blobdata txid_data;
if(!epee::string_tools::parse_hexstr_to_binbuff(args[0], txid_data) || txid_data.size() != sizeof(crypto::hash))
{
fail_msg_writer() << tr("failed to parse txid");
return true;
}
crypto::hash txid = *reinterpret_cast<const crypto::hash*>(txid_data.data());
cryptonote::account_public_address address;
bool has_payment_id;
crypto::hash8 payment_id;
if(!cryptonote::get_account_address_from_str_or_url(address, has_payment_id, payment_id, m_wallet->testnet(), args[1]))
{
fail_msg_writer() << tr("failed to parse address");
return true;
}
LOCK_IDLE_SCOPE();
crypto::secret_key tx_key, tx_key2;
bool r = m_wallet->get_tx_key(txid, tx_key);
cryptonote::blobdata tx_key_data;
if (args.size() == 3)
{
if(!epee::string_tools::parse_hexstr_to_binbuff(args[2], tx_key_data) || tx_key_data.size() != sizeof(crypto::secret_key))
{
fail_msg_writer() << tr("failed to parse tx_key");
return true;
}
tx_key2 = *reinterpret_cast<const crypto::secret_key*>(tx_key_data.data());
}
if (r)
{
if (args.size() == 3 && tx_key != rct::sk2rct(tx_key2))
{
fail_msg_writer() << tr("Tx secret key was found for the given txid, but you've also provided another tx secret key which doesn't match the found one.");
return true;
}
}
else
{
if (tx_key_data.empty())
{
fail_msg_writer() << tr("Tx secret key wasn't found in the wallet file. Provide it as the optional third parameter if you have it elsewhere.");
return true;
}
tx_key = tx_key2;
}
crypto::public_key R;
crypto::secret_key_to_public_key(tx_key, R);
crypto::public_key rA = rct::rct2pk(rct::scalarmultKey(rct::pk2rct(address.m_view_public_key), rct::sk2rct(tx_key)));
crypto::signature sig;
try
{
crypto::generate_tx_proof(txid, R, address.m_view_public_key, rA, tx_key, sig);
}
catch (const std::runtime_error &e)
{
fail_msg_writer() << e.what();
return true;
}
std::string sig_str = std::string("ProofV1") +
tools::base58::encode(std::string((const char *)&rA, sizeof(crypto::public_key))) +
tools::base58::encode(std::string((const char *)&sig, sizeof(crypto::signature)));
success_msg_writer() << tr("Signature: ") << sig_str;
return true;
}
//----------------------------------------------------------------------------------------------------
bool simple_wallet::check_tx_key(const std::vector<std::string> &args_) bool simple_wallet::check_tx_key(const std::vector<std::string> &args_)
{ {
std::vector<std::string> local_args = args_; std::vector<std::string> local_args = args_;
@ -3278,6 +3360,18 @@ bool simple_wallet::check_tx_key(const std::vector<std::string> &args_)
return true; return true;
} }
crypto::key_derivation derivation;
if (!crypto::generate_key_derivation(address.m_view_public_key, tx_key, derivation))
{
fail_msg_writer() << tr("failed to generate key derivation from supplied parameters");
return true;
}
return check_tx_key_helper(txid, address, derivation);
}
//----------------------------------------------------------------------------------------------------
bool simple_wallet::check_tx_key_helper(const crypto::hash &txid, const cryptonote::account_public_address &address, const crypto::key_derivation &derivation)
{
COMMAND_RPC_GET_TRANSACTIONS::request req; COMMAND_RPC_GET_TRANSACTIONS::request req;
COMMAND_RPC_GET_TRANSACTIONS::response res; COMMAND_RPC_GET_TRANSACTIONS::response res;
req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid)); req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid));
@ -3311,13 +3405,6 @@ bool simple_wallet::check_tx_key(const std::vector<std::string> &args_)
return true; return true;
} }
crypto::key_derivation derivation;
if (!crypto::generate_key_derivation(address.m_view_public_key, tx_key, derivation))
{
fail_msg_writer() << tr("failed to generate key derivation from supplied parameters");
return true;
}
uint64_t received = 0; uint64_t received = 0;
try { try {
for (size_t n = 0; n < tx.vout.size(); ++n) for (size_t n = 0; n < tx.vout.size(); ++n)
@ -3340,14 +3427,6 @@ bool simple_wallet::check_tx_key(const std::vector<std::string> &args_)
{ {
rct::key Ctmp; rct::key Ctmp;
//rct::key amount_key = rct::hash_to_scalar(rct::scalarmultKey(rct::pk2rct(address.m_view_public_key), rct::sk2rct(tx_key))); //rct::key amount_key = rct::hash_to_scalar(rct::scalarmultKey(rct::pk2rct(address.m_view_public_key), rct::sk2rct(tx_key)));
crypto::key_derivation derivation;
bool r = crypto::generate_key_derivation(address.m_view_public_key, tx_key, derivation);
if (!r)
{
LOG_ERROR("Failed to generate key derivation to decode rct output " << n);
amount = 0;
}
else
{ {
crypto::secret_key scalar1; crypto::secret_key scalar1;
crypto::derivation_to_scalar(derivation, n, scalar1); crypto::derivation_to_scalar(derivation, n, scalar1);
@ -3404,6 +3483,129 @@ bool simple_wallet::check_tx_key(const std::vector<std::string> &args_)
return true; return true;
} }
//---------------------------------------------------------------------------------------------------- //----------------------------------------------------------------------------------------------------
bool simple_wallet::check_tx_proof(const std::vector<std::string> &args)
{
if(args.size() != 3) {
fail_msg_writer() << tr("usage: check_tx_proof <txid> <address> <signature>");
return true;
}
if (!try_connect_to_daemon())
return true;
// parse txid
cryptonote::blobdata txid_data;
if(!epee::string_tools::parse_hexstr_to_binbuff(args[0], txid_data) || txid_data.size() != sizeof(crypto::hash))
{
fail_msg_writer() << tr("failed to parse txid");
return true;
}
crypto::hash txid = *reinterpret_cast<const crypto::hash*>(txid_data.data());
// parse address
cryptonote::account_public_address address;
bool has_payment_id;
crypto::hash8 payment_id;
if(!cryptonote::get_account_address_from_str_or_url(address, has_payment_id, payment_id, m_wallet->testnet(), args[1]))
{
fail_msg_writer() << tr("failed to parse address");
return true;
}
// parse pubkey r*A & signature
std::string sig_str = args[2];
const size_t header_len = strlen("ProofV1");
if (sig_str.size() < header_len || sig_str.substr(0, header_len) != "ProofV1")
{
fail_msg_writer() << tr("Signature header check error");
return true;
}
crypto::public_key rA;
crypto::signature sig;
const size_t rA_len = tools::base58::encode(std::string((const char *)&rA, sizeof(crypto::public_key))).size();
const size_t sig_len = tools::base58::encode(std::string((const char *)&sig, sizeof(crypto::signature))).size();
std::string rA_decoded;
std::string sig_decoded;
if (!tools::base58::decode(sig_str.substr(header_len, rA_len), rA_decoded))
{
fail_msg_writer() << tr("Signature decoding error");
return true;
}
if (!tools::base58::decode(sig_str.substr(header_len + rA_len, sig_len), sig_decoded))
{
fail_msg_writer() << tr("Signature decoding error");
return true;
}
if (sizeof(crypto::public_key) != rA_decoded.size() || sizeof(crypto::signature) != sig_decoded.size())
{
fail_msg_writer() << tr("Signature decoding error");
return true;
}
memcpy(&rA, rA_decoded.data(), sizeof(crypto::public_key));
memcpy(&sig, sig_decoded.data(), sizeof(crypto::signature));
// fetch tx pubkey from the daemon
COMMAND_RPC_GET_TRANSACTIONS::request req;
COMMAND_RPC_GET_TRANSACTIONS::response res;
req.txs_hashes.push_back(epee::string_tools::pod_to_hex(txid));
if (!net_utils::invoke_http_json("/gettransactions", req, res, m_http_client) ||
(res.txs.size() != 1 && res.txs_as_hex.size() != 1))
{
fail_msg_writer() << tr("failed to get transaction from daemon");
return true;
}
cryptonote::blobdata tx_data;
bool ok;
if (res.txs.size() == 1)
ok = string_tools::parse_hexstr_to_binbuff(res.txs.front().as_hex, tx_data);
else
ok = string_tools::parse_hexstr_to_binbuff(res.txs_as_hex.front(), tx_data);
if (!ok)
{
fail_msg_writer() << tr("failed to parse transaction from daemon");
return true;
}
crypto::hash tx_hash, tx_prefix_hash;
cryptonote::transaction tx;
if (!cryptonote::parse_and_validate_tx_from_blob(tx_data, tx, tx_hash, tx_prefix_hash))
{
fail_msg_writer() << tr("failed to validate transaction from daemon");
return true;
}
if (tx_hash != txid)
{
fail_msg_writer() << tr("failed to get the right transaction from daemon");
return true;
}
crypto::public_key R = get_tx_pub_key_from_extra(tx);
if (R == null_pkey)
{
fail_msg_writer() << tr("Tx pubkey was not found");
return true;
}
// check signature
if (crypto::check_tx_proof(txid, R, address.m_view_public_key, rA, sig))
{
success_msg_writer() << tr("Good signature");
}
else
{
fail_msg_writer() << tr("Bad signature");
return true;
}
// obtain key derivation by multiplying scalar 1 to the pubkey r*A included in the signature
crypto::key_derivation derivation;
if (!crypto::generate_key_derivation(rA, rct::rct2sk(rct::I), derivation))
{
fail_msg_writer() << tr("failed to generate key derivation");
return true;
}
return check_tx_key_helper(txid, address, derivation);
}
//----------------------------------------------------------------------------------------------------
static std::string get_human_readable_timestamp(uint64_t ts) static std::string get_human_readable_timestamp(uint64_t ts)
{ {
char buffer[64]; char buffer[64];

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@ -154,6 +154,9 @@ namespace cryptonote
bool set_log(const std::vector<std::string> &args); bool set_log(const std::vector<std::string> &args);
bool get_tx_key(const std::vector<std::string> &args); bool get_tx_key(const std::vector<std::string> &args);
bool check_tx_key(const std::vector<std::string> &args); bool check_tx_key(const std::vector<std::string> &args);
bool check_tx_key_helper(const crypto::hash &txid, const cryptonote::account_public_address &address, const crypto::key_derivation &derivation);
bool get_tx_proof(const std::vector<std::string> &args);
bool check_tx_proof(const std::vector<std::string> &args);
bool show_transfers(const std::vector<std::string> &args); bool show_transfers(const std::vector<std::string> &args);
bool unspent_outputs(const std::vector<std::string> &args); bool unspent_outputs(const std::vector<std::string> &args);
bool rescan_blockchain(const std::vector<std::string> &args); bool rescan_blockchain(const std::vector<std::string> &args);