diff --git a/app/src/crypto_helper.c b/app/src/crypto_helper.c
index 2e1bd15..9d71915 100644
--- a/app/src/crypto_helper.c
+++ b/app/src/crypto_helper.c
@@ -39,7 +39,7 @@ zxerr_t crypto_sha256(const uint8_t *input, uint16_t inputLen, uint8_t *output,
     MEMZERO(output, outputLen);
 
 #if defined(TARGET_NANOS) || defined(TARGET_NANOS2) || defined(TARGET_NANOX) || defined(TARGET_STAX)
-    cx_hash_sha256(input, inputLen, output, CX_SHA256_SIZE);
+    CHECK_CXERROR(cx_hash_sha256(input, inputLen, output, CX_SHA256_SIZE));
 #else
     picohash_ctx_t ctx;
     picohash_init_sha256(&ctx);
diff --git a/app/src/parser_impl.c b/app/src/parser_impl.c
index d7d6f86..df0d471 100644
--- a/app/src/parser_impl.c
+++ b/app/src/parser_impl.c
@@ -118,7 +118,7 @@ static parser_error_t parser_get_network_id(parser_context_t *c, parser_tx_t *v)
 
 static parser_error_t parser_verify_codec(parser_context_t *ctx) {
     uint16_t codec = 0;
-    read_u16(ctx, &codec);
+    CHECK_ERROR(read_u16(ctx, &codec));
     if (codec != 0) {
         return parser_invalid_codec;
     }
diff --git a/app/src/parser_impl_common.c b/app/src/parser_impl_common.c
index a840c1b..fae5607 100644
--- a/app/src/parser_impl_common.c
+++ b/app/src/parser_impl_common.c
@@ -48,6 +48,11 @@ static const uint32_t chain_lookup_len = sizeof(chain_lookup_table) / sizeof(cha
     CTX_CHECK_AVAIL((CTX), (SIZE))       \
     (CTX)->offset += (SIZE);
 
+#define CTX_CHECK_BUFFER(CTX)                                  \
+    if ((CTX) == NULL || ((CTX)->offset > (CTX)->bufferLen)) { \
+        return parser_unexpected_buffer_end;                   \
+    }
+
 parser_error_t read_u64(parser_context_t *ctx, uint64_t *result) {
     if (result == NULL) {
         return parser_unexpected_error;
@@ -109,6 +114,16 @@ parser_error_t read_u8(parser_context_t *ctx, uint8_t *result) {
     return parser_ok;
 }
 
+parser_error_t checkAvailableBytes(parser_context_t *ctx, uint16_t buffLen) {
+    CTX_CHECK_AVAIL(ctx, buffLen)
+    return parser_ok;
+}
+
+parser_error_t verifyContext(parser_context_t *ctx) {
+    CTX_CHECK_BUFFER(ctx)
+    return parser_ok;
+}
+
 parser_error_t verifyBytes(parser_context_t *ctx, uint16_t buffLen) {
     CTX_CHECK_AVAIL(ctx, buffLen)
     CTX_CHECK_AND_ADVANCE(ctx, buffLen)
diff --git a/app/src/parser_impl_common.h b/app/src/parser_impl_common.h
index 8ded570..5e7f5ba 100644
--- a/app/src/parser_impl_common.h
+++ b/app/src/parser_impl_common.h
@@ -26,6 +26,8 @@ parser_error_t read_u32(parser_context_t *ctx, uint32_t *result);
 parser_error_t read_u64(parser_context_t *ctx, uint64_t *result);
 parser_error_t verifyBytes(parser_context_t *ctx, uint16_t buffLen);
 parser_error_t readBytes(parser_context_t *ctx, uint8_t *buff, uint16_t buffLen);
+parser_error_t checkAvailableBytes(parser_context_t *ctx, uint16_t buffLen);
+parser_error_t verifyContext(parser_context_t *ctx);
 
 parser_error_t parser_get_chain_id(parser_context_t *c, parser_tx_t *v);
 parser_error_t parser_get_chain_alias(const uint8_t *blockchain_id, char *chain);
diff --git a/app/src/parser_print_common.c b/app/src/parser_print_common.c
index 8959b46..f98b0f5 100644
--- a/app/src/parser_print_common.c
+++ b/app/src/parser_print_common.c
@@ -22,8 +22,6 @@
 #include "zxformat.h"
 #include "zxmacros.h"
 
-#define ALPHABET_ENCODE "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
-
 #if defined(TARGET_NANOS) || defined(TARGET_NANOS2) || defined(TARGET_NANOX) || defined(TARGET_STAX)
 #include "cx.h"
 #include "cx_sha256.h"
@@ -106,10 +104,10 @@ parser_error_t printAddress(const uint8_t *pubkey, network_id_e network_id, char
     const char *hrp = "";
     switch (network_id) {
         case songbird:
-            hrp = " song";
+            hrp = "song";
             break;
         case coston:
-            hrp = " costwo";
+            hrp = "costwo";
             break;
         case coston2:
             hrp = "costwo";
@@ -161,7 +159,7 @@ parser_error_t printNodeId(const uint8_t *nodeId, char *outVal, uint16_t outValL
     // Calculate SHA256 checksum
     uint8_t checksum[CX_SHA256_SIZE] = {0};
 #if defined(TARGET_NANOS) || defined(TARGET_NANOS2) || defined(TARGET_NANOX) || defined(TARGET_STAX)
-    cx_hash_sha256(nodeId, NODE_ID_LEN, checksum, CX_SHA256_SIZE);
+    CHECK_CXERROR(cx_hash_sha256(nodeId, NODE_ID_LEN, checksum, CX_SHA256_SIZE));
 #else
     picohash_ctx_t ctx;
     picohash_init_sha256(&ctx);
diff --git a/app/src/tx_cchain.c b/app/src/tx_cchain.c
index eb46b0a..d4474be 100644
--- a/app/src/tx_cchain.c
+++ b/app/src/tx_cchain.c
@@ -22,6 +22,7 @@
 
 static parser_error_t parser_handle_cchain_export(parser_context_t *c, parser_tx_t *v) {
     // Get destination chain
+    CHECK_ERROR(checkAvailableBytes(c, BLOCKCHAIN_ID_LEN));
     v->tx.c_export_tx.destination_chain = c->buffer + c->offset;
     if (!MEMCMP(v->tx.c_export_tx.destination_chain, v->blockchain_id, BLOCKCHAIN_ID_LEN)) {
         return parser_unexpected_chain;
@@ -35,6 +36,7 @@ static parser_error_t parser_handle_cchain_export(parser_context_t *c, parser_tx
     }
 
     // Pointer to inputs
+    CHECK_ERROR(verifyContext(c));
     v->tx.c_export_tx.evm_inputs.ins = c->buffer + c->offset;
     CHECK_ERROR(parse_evm_inputs(c, &v->tx.c_export_tx.evm_inputs));
 
@@ -46,6 +48,7 @@ static parser_error_t parser_handle_cchain_export(parser_context_t *c, parser_tx
 
     // Pointer to outputs
     if (v->tx.c_export_tx.secp_outs.n_outs > 0) {
+        CHECK_ERROR(verifyContext(c));
         v->tx.c_export_tx.secp_outs.outs = c->buffer + c->offset;
         v->tx.c_export_tx.secp_outs.outs_offset = c->offset;
         CHECK_ERROR(parse_transferable_secp_output(c, &v->tx.c_export_tx.secp_outs, false));
@@ -56,6 +59,7 @@ static parser_error_t parser_handle_cchain_export(parser_context_t *c, parser_tx
 
 static parser_error_t parser_handle_cchain_import(parser_context_t *c, parser_tx_t *v) {
     // Get source chain
+    CHECK_ERROR(checkAvailableBytes(c, BLOCKCHAIN_ID_LEN));
     v->tx.c_import_tx.source_chain = c->buffer + c->offset;
     if (!MEMCMP(v->tx.c_import_tx.source_chain, v->blockchain_id, BLOCKCHAIN_ID_LEN)) {
         return parser_unexpected_chain;
@@ -69,6 +73,7 @@ static parser_error_t parser_handle_cchain_import(parser_context_t *c, parser_tx
     }
 
     // Pointer to inputs
+    CHECK_ERROR(verifyContext(c));
     v->tx.c_import_tx.secp_inputs.ins = c->buffer + c->offset;
     CHECK_ERROR(parse_transferable_secp_input(c, &v->tx.c_import_tx.secp_inputs));
 
@@ -80,6 +85,7 @@ static parser_error_t parser_handle_cchain_import(parser_context_t *c, parser_tx
 
     // Pointer to outputs
     if (v->tx.c_import_tx.evm_outs.n_outs > 0) {
+        CHECK_ERROR(verifyContext(c));
         v->tx.c_import_tx.evm_outs.outs = c->buffer + c->offset;
         v->tx.c_import_tx.evm_outs.outs_offset = c->offset;
         CHECK_ERROR(parse_evm_output(c, &v->tx.c_import_tx.evm_outs));
diff --git a/app/src/tx_pchain.c b/app/src/tx_pchain.c
index c65a5fc..dbb78b8 100644
--- a/app/src/tx_pchain.c
+++ b/app/src/tx_pchain.c
@@ -29,6 +29,7 @@ static parser_error_t parser_base_tx(parser_context_t *c, transferable_in_secp_t
 
     // Pointer to outputs
     if (outputs->n_outs > 0) {
+        CHECK_ERROR(verifyContext(c));
         outputs->outs = c->buffer + c->offset;
         CHECK_ERROR(parse_transferable_secp_output(c, outputs, true));
     }
@@ -38,6 +39,7 @@ static parser_error_t parser_base_tx(parser_context_t *c, transferable_in_secp_t
 
     // Pointer to inputs
     if (inputs->n_ins > 0) {
+        CHECK_ERROR(verifyContext(c));
         inputs->ins = c->buffer + c->offset;
         CHECK_ERROR(parse_transferable_secp_input(c, inputs));
     }
@@ -57,6 +59,7 @@ parser_error_t parser_handle_p_export_tx(parser_context_t *c, parser_tx_t *v) {
     CHECK_ERROR(parser_base_tx(c, &v->tx.p_export_tx.base_secp_ins, &v->tx.p_export_tx.base_secp_outs));
 
     // Get destination chain
+    CHECK_ERROR(checkAvailableBytes(c, BLOCKCHAIN_ID_LEN));
     v->tx.p_export_tx.destination_chain = c->buffer + c->offset;
     if (!MEMCMP(PIC(v->tx.p_export_tx.destination_chain), v->blockchain_id, BLOCKCHAIN_ID_LEN)) {
         return parser_unexpected_chain;
@@ -70,6 +73,7 @@ parser_error_t parser_handle_p_export_tx(parser_context_t *c, parser_tx_t *v) {
     }
 
     // Pointer to outputs
+    CHECK_ERROR(verifyContext(c));
     v->tx.p_export_tx.secp_outs.outs = c->buffer + c->offset;
     v->tx.p_export_tx.secp_outs.outs_offset = c->offset;
     CHECK_ERROR(parse_transferable_secp_output(c, &v->tx.p_export_tx.secp_outs, true));
@@ -82,6 +86,7 @@ parser_error_t parser_handle_p_import_tx(parser_context_t *c, parser_tx_t *v) {
     CHECK_ERROR(parser_base_tx(c, &v->tx.p_import_tx.base_secp_ins, &v->tx.p_import_tx.base_secp_outs));
 
     // Get source chain
+    CHECK_ERROR(checkAvailableBytes(c, BLOCKCHAIN_ID_LEN));
     v->tx.p_import_tx.source_chain = c->buffer + c->offset;
     if (!MEMCMP(v->tx.p_import_tx.source_chain, v->blockchain_id, BLOCKCHAIN_ID_LEN)) {
         return parser_unexpected_chain;
@@ -95,6 +100,7 @@ parser_error_t parser_handle_p_import_tx(parser_context_t *c, parser_tx_t *v) {
     }
 
     // Pointer to inputs
+    CHECK_ERROR(verifyContext(c));
     v->tx.p_import_tx.secp_ins.ins = c->buffer + c->offset;
     v->tx.p_import_tx.secp_ins.ins_offset = c->offset;
     CHECK_ERROR(parse_transferable_secp_input(c, &v->tx.p_import_tx.secp_ins));
@@ -107,6 +113,7 @@ parser_error_t parser_handle_add_delegator_validator(parser_context_t *c, parser
     CHECK_ERROR(parser_base_tx(c, &v->tx.add_del_val_tx.base_secp_ins, &v->tx.add_del_val_tx.base_secp_outs));
 
     // Node ID
+    CHECK_ERROR(verifyContext(c));
     v->tx.add_del_val_tx.node_id = c->buffer + c->offset;
     CHECK_ERROR(verifyBytes(c, NODE_ID_LEN));
 
@@ -130,6 +137,7 @@ parser_error_t parser_handle_add_delegator_validator(parser_context_t *c, parser
     }
 
     // Pointer to outputs
+    CHECK_ERROR(verifyContext(c));
     v->tx.add_del_val_tx.staked_outs.outs = c->buffer + c->offset;
     CHECK_ERROR(parse_transferable_secp_output(c, &v->tx.add_del_val_tx.staked_outs, false));
 
@@ -138,6 +146,7 @@ parser_error_t parser_handle_add_delegator_validator(parser_context_t *c, parser
     }
 
     // Pointer to owners output
+    CHECK_ERROR(verifyContext(c));
     v->tx.add_del_val_tx.owners_out.outs = c->buffer + c->offset;
     v->tx.add_del_val_tx.owners_out.n_outs = 1;
     CHECK_ERROR(parse_secp_owners_output(c, &v->tx.add_del_val_tx.owners_out));
diff --git a/docs/APDUSPEC.md b/docs/APDUSPEC.md
index b7331c8..ab492a2 100644
--- a/docs/APDUSPEC.md
+++ b/docs/APDUSPEC.md
@@ -54,7 +54,7 @@ The general structure of commands and responses is as follows:
 | INS   | byte (1) | Instruction ID         | 0x00     |
 | P1    | byte (1) | Parameter 1            | ignored  |
 | P2    | byte (1) | Parameter 2            | ignored  |
-| L     | byte (1) | Bytes in payload       | 0x0      |
+| L     | byte (1) | Bytes in payload       | 0        |
 
 #### Response