implement single account mode

src/securityPolicy.c

@@ -2,6 +2,7 @@
 #include "addressUtilsByron.h"
 #include "bip44.h"
 #include "cardano.h"
+#include "singleAccount.h"
 
 #include "securityPolicy.h"
 
@@ -365,6 +366,7 @@ security_policy_t policyForSignTxOutputAddressParams(
 	case SIGN_TX_SIGNINGMODE_POOL_REGISTRATION_OPERATOR:
 	case SIGN_TX_SIGNINGMODE_ORDINARY_TX: {
 		DENY_UNLESS(determineSpendingChoice(params->type) == SPENDING_PATH);
+		DENY_IF(violatesSingleAccount(&params->spendingKeyPath));
 		SHOW_UNLESS(is_standard_base_address(params));
 		ALLOW();
 		break;
@@ -504,6 +506,7 @@ security_policy_t policyForSignTxCertificateStaking(
 	case SIGN_TX_SIGNINGMODE_ORDINARY_TX:
 		DENY_UNLESS(stakeCredential->type == STAKE_CREDENTIAL_KEY_PATH);
 		DENY_UNLESS(bip44_isOrdinaryStakingKeyPath(&stakeCredential->keyPath));
+		DENY_IF(violatesSingleAccount(&stakeCredential->keyPath));
 		break;
 	case SIGN_TX_SIGNINGMODE_MULTISIG_TX:
 		DENY_UNLESS(stakeCredential->type == STAKE_CREDENTIAL_SCRIPT_HASH);
@@ -606,6 +609,7 @@ security_policy_t policyForSignTxStakePoolRegistrationOwner(
 {
 	if (owner->keyReferenceType == KEY_REFERENCE_PATH) {
 		DENY_UNLESS(bip44_isOrdinaryStakingKeyPath(&owner->path));
+		DENY_IF(violatesSingleAccount(&owner->path));
 	}
 
 	switch (txSigningMode) {
@@ -675,6 +679,7 @@ security_policy_t policyForSignTxWithdrawal(
 	case SIGN_TX_SIGNINGMODE_ORDINARY_TX:
 		DENY_UNLESS(stakeCredential->type == STAKE_CREDENTIAL_KEY_PATH);
 		DENY_UNLESS(bip44_isOrdinaryStakingKeyPath(&stakeCredential->keyPath));
+		DENY_IF(violatesSingleAccount(&stakeCredential->keyPath));
 		SHOW();
 		break;
 
@@ -694,6 +699,8 @@ static inline security_policy_t _ordinaryWitnessPolicy(const bip44_path_t* path,
 {
 	switch (bip44_classifyPath(path)) {
 	case PATH_ORDINARY_SPENDING_KEY:
+		DENY_IF(violatesSingleAccount(path));
+		// intentional fallthrough
 	case PATH_ORDINARY_STAKING_KEY:
 	case PATH_POOL_COLD_KEY:
 		WARN_UNLESS(bip44_isPathReasonable(path));

src/signTx.h

@@ -54,12 +54,19 @@ enum {
 	SIGN_MAX_WITNESSES = SIGN_MAX_INPUTS + SIGN_MAX_OUTPUTS + SIGN_MAX_CERTIFICATES + SIGN_MAX_REWARD_WITHDRAWALS,
 };
 
+typedef struct {
+	bool pathSet;
+	bip44_path_t path;
+} single_account_data_t;
+
 typedef struct {
 	// significantly affects restrictions on the tx
 	sign_tx_signingmode_t txSigningMode;
 
 	uint8_t networkId; // part of Shelley address
 	uint32_t protocolMagic; // part of Byron address
+
+	single_account_data_t singleAccountData;
 } common_tx_data_t;
 
 typedef struct {

src/singleAccount.c

@@ -0,0 +1,24 @@
+#include "state.h"
+
+static common_tx_data_t* commonData = &(instructionState.signTxContext.commonTxData);
+
+bool violatesSingleAccount(const bip44_path_t* path)
+{
+    if (!bip44_hasOrdinaryWalletKeyPrefix(path) || !bip44_containsAccount(path)) {
+        return false;
+    }
+    if (commonData->singleAccountData.pathSet) {
+        const uint32_t storedAccount = bip44_getAccount(&commonData->singleAccountData.path);
+        if (bip44_getAccount(path) != storedAccount) {
+            return true;
+        }
+        if ((bip44_hasByronPrefix(path) || bip44_hasByronPrefix(&commonData->singleAccountData.path))
+            && storedAccount != 0) {
+            return true;
+        }
+    } else {
+        memcpy(&commonData->singleAccountData.path, path, SIZEOF(*path));
+        commonData->singleAccountData.pathSet = true;
+    }
+    return false;
+}

src/singleAccount.h

@@ -0,0 +1,8 @@
+#ifndef H_CARDANO_APP_SINGLE_ACCOUNT
+#define H_CARDANO_APP_SINGLE_ACCOUNT
+
+#include "bip44.h"
+
+bool violatesSingleAccount(const bip44_path_t* path);
+
+#endif  // H_CARDANO_APP_SINGLE_ACCOUNT