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MRTD proper parse DO87 multi byte length

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This commit is contained in:
Chris van Marle
2022-10-11 22:13:39 +02:00
parent d3d9b67544
commit 0ab7d91fb4
2 changed files with 22 additions and 11 deletions
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lib/nfc/protocols/mrtd_helpers.c
+16 -5
View File
@@ -1,4 +1,5 @@
#include "mrtd_helpers.h"
#include "../helpers/iso7816.h"
#include <stdio.h> //TODO: remove
#include <stdlib.h>
@@ -185,15 +186,25 @@ uint16_t mrtd_bac_decrypt_verify_sm(const uint8_t* data, size_t data_length, uin
uint16_t ret_code = data[data_length - 10 - 2] <<8 | data[data_length - 10 - 1];
//ntohs(data + data_length - 10 - 2);
if(data[0] == 0x87) {
TlvInfo do87 = iso7816_tlv_select(data, data_length, (uint16_t[]){0x87}, 1);
//printf("DO87.Tag: %X\n", do87.tag);
//printf("DO87.Length: %ld\n", do87.length);
//printf("DO87.Value: ");
//for(uint8_t i=1; i<do87.length; ++i) { printf("%02X ", do87.value[i]); }
//printf("\r\n");
if(do87.tag) {
if(output_written != NULL && output != NULL) {
uint8_t do87_length = data[1] - 1;
mrtd_bac_decrypt(data + 3, do87_length, key_enc, output);
printf("Decrypted: "); for(uint8_t i=0; i<do87_length; ++i) printf("%02X ", output[i]); printf("\r\n");
// Skip the first byte '01'
const uint8_t* encdata = do87.value + 1;
size_t enclength = do87.length - 1;
mrtd_bac_decrypt(encdata, enclength, key_enc, output);
printf("Decrypted: "); for(uint8_t i=0; i<enclength; ++i) printf("%02X ", output[i]); printf("\r\n");
//TODO: function mrtd_bac_unpad?
int padidx;
for(padidx=do87_length-1; padidx>=0; --padidx) {
for(padidx=enclength-1; padidx>=0; --padidx) {
if(output[padidx] == 0x00) {
continue;
} else if(output[padidx] == 0x80) {