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emrtd: Improve and clean asn1datalength and asn1fieldlength

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This commit is contained in:
Ave 2020-12-12 20:55:16 +03:00
parent a895fbd3c6
commit 42e6763ea1
1 changed files with 30 additions and 39 deletions
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69
client/src/cmdhfemrtd.c
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@ -108,41 +108,34 @@ static char calculate_check_digit(char *data) {
return cd % 10;
}
static int asn1datalength(uint8_t *datain, int datainlen) {
char *dataintext = sprint_hex_inrow(datain, datainlen);
// lazy - https://stackoverflow.com/a/4214350/3286892
char subbuff[8];
int thing = *(datain + 1);
if (thing <= 0x7f) {
return thing;
} else if (thing == 0x81) {
memcpy(subbuff, &dataintext[2], 3);
subbuff[3] = '\0';
return (int)strtol(subbuff, NULL, 16);
} else if (thing == 0x82) {
memcpy(subbuff, &dataintext[2], 5);
subbuff[5] = '\0';
return (int)strtol(subbuff, NULL, 16);
} else if (thing == 0x83) {
memcpy(subbuff, &dataintext[2], 7);
subbuff[7] = '\0';
return (int)strtol(subbuff, NULL, 16);
static int asn1datalength(uint8_t *datain, int datainlen, int offset) {
PrintAndLogEx(DEBUG, "asn1datalength, datain: %s", sprint_hex_inrow(datain, datainlen));
int lenfield = (int) *(datain + offset);
PrintAndLogEx(DEBUG, "asn1datalength, lenfield: %i", lenfield);
if (lenfield <= 0x7f) {
return lenfield;
} else if (lenfield == 0x81) {
return ((int) *(datain + offset + 1));
} else if (lenfield == 0x82) {
return ((int) *(datain + offset + 1) << 8) | ((int) *(datain + offset + 2));
} else if (lenfield == 0x83) {
return (((int) *(datain + offset + 1) << 16) | ((int) *(datain + offset + 2)) << 8) | ((int) *(datain + offset + 3));
}
return false;
}
static int asn1fieldlength(uint8_t *datain, int datainlen) {
int thing = *(datain + 1);
if (thing <= 0x7f) {
static int asn1fieldlength(uint8_t *datain, int datainlen, int offset) {
PrintAndLogEx(DEBUG, "asn1fieldlength, datain: %s", sprint_hex_inrow(datain, datainlen));
int lenfield = (int) *(datain + offset);
PrintAndLogEx(DEBUG, "asn1fieldlength, thing: %i", lenfield);
if (lenfield <= 0x7f) {
return 1;
} else if (lenfield == 0x81) {
return 2;
} else if (thing == 0x81) {
} else if (lenfield == 0x82) {
return 3;
} else if (lenfield == 0x83) {
return 4;
} else if (thing == 0x82) {
return 6;
} else if (thing == 0x83) {
return 8;
}
return false;
}
@ -310,8 +303,8 @@ static int read_file(uint8_t *dataout, int *dataoutlen) {
return false;
}
int datalen = asn1datalength(response, resplen);
int readlen = datalen - (3 - asn1fieldlength(response, resplen) / 2);
int datalen = asn1datalength(response, resplen, 1);
int readlen = datalen - (3 - asn1fieldlength(response, resplen, 1));
int offset = 4;
int toread;
@ -501,22 +494,20 @@ static bool _secure_read_binary_decrypt(uint8_t *kenc, uint8_t *kmac, uint8_t *s
return false;
}
PrintAndLogEx(DEBUG, "0offset %i on %i: ? (crypt: %s)", offset, bytes_to_read, sprint_hex_inrow(response, resplen));
PrintAndLogEx(DEBUG, "secreadbindec, offset %i on read %i: encrypted: %s", offset, bytes_to_read, sprint_hex_inrow(response, resplen));
cutat = ((int) response[1]) - 1;
PrintAndLogEx(DEBUG, "1offset %i on %i: ? (crypt: %s)", offset, bytes_to_read, sprint_hex_inrow(response, resplen));
des3_decrypt_cbc(iv, kenc, response + 3, cutat, temp);
PrintAndLogEx(DEBUG, "2eoffset %i on %i: ? (crypt: %s)", offset, bytes_to_read, sprint_hex_inrow(response, resplen));
PrintAndLogEx(DEBUG, "2aoffset %i on %i: %s", offset, bytes_to_read, sprint_hex_inrow(temp, cutat));
PrintAndLogEx(DEBUG, "2boffset %i on %i: c %s", offset, bytes_to_read, sprint_hex_inrow(response, resplen));
memcpy(dataout, temp, bytes_to_read);
PrintAndLogEx(DEBUG, "3offset %i on %i: %s (crypt: %s)", offset, bytes_to_read, sprint_hex_inrow(temp, cutat), sprint_hex_inrow(response, resplen));
PrintAndLogEx(DEBUG, "secreadbindec, offset %i on read %i: decrypted: %s", offset, bytes_to_read, sprint_hex_inrow(temp, cutat));
PrintAndLogEx(DEBUG, "secreadbindec, offset %i on read %i: decrypted and cut: %s", offset, bytes_to_read, sprint_hex_inrow(dataout, bytes_to_read));
*dataoutlen = bytes_to_read;
return true;
}
static int secure_read_file(uint8_t *kenc, uint8_t *kmac, uint8_t *ssc, uint8_t *dataout, int *dataoutlen) {
// TODO: join this with regular read file
uint8_t response[500];
int resplen = 0;
uint8_t tempresponse[500];
@ -526,8 +517,8 @@ static int secure_read_file(uint8_t *kenc, uint8_t *kmac, uint8_t *ssc, uint8_t
return false;
}
int datalen = asn1datalength(response, resplen);
int readlen = datalen - (3 - asn1fieldlength(response, resplen) / 2);
int datalen = asn1datalength(response, resplen, 1);
int readlen = datalen - (3 - asn1fieldlength(response, resplen, 1));
int offset = 4;
int toread;