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asn1 decoder now handles big integers

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This commit is contained in:
iceman1001 2023-03-13 22:09:30 +01:00
commit 1cc19c3429
1 changed files with 28 additions and 40 deletions
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68
client/src/crypto/asn1dump.c
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@ -26,6 +26,7 @@
#include <string.h>
#include <jansson.h>
#include <mbedtls/asn1.h>
#include "mbedtls/bignum.h" // big num
#include <mbedtls/oid.h>
#include "emv/emv_tags.h"
#include "emv/emvjson.h"
@ -239,36 +240,6 @@ static void asn1_tag_dump_octet_string(const struct tlv *tlv, const struct asn1_
}
}
static uint64_t asn1_value_integer(const struct tlv *tlv, unsigned start, unsigned end) {
uint64_t ret = 0;
unsigned i;
if (end > tlv->len * 2)
return ret;
if (start >= end)
return ret;
if (start & 1) {
ret += tlv->value[start / 2] & 0xf;
i = start + 1;
} else
i = start;
for (; i < end - 1; i += 2) {
ret = ret << 4; // was: ret*=10
ret += tlv->value[i / 2] >> 4;
ret = ret << 4; // was: ret*=10
ret += tlv->value[i / 2] & 0xf;
}
if (end & 1) {
ret = ret << 4; // was: ret*=10
ret += tlv->value[end / 2] >> 4;
}
return ret;
}
static void asn1_tag_dump_boolean(const struct tlv *tlv, const struct asn1_tag *tag, int level) {
PrintAndLogEx(NORMAL, "%*s" NOLF, (level * 4), " ");
if (tlv->len > 0) {
@ -279,17 +250,34 @@ static void asn1_tag_dump_boolean(const struct tlv *tlv, const struct asn1_tag *
}
static void asn1_tag_dump_integer(const struct tlv *tlv, const struct asn1_tag *tag, int level) {
PrintAndLogEx(NORMAL, "%*s" NOLF, (level * 4), " ");
if (tlv->len == 4) {
int32_t val = 0;
for (size_t i = 0; i < tlv->len; i++) {
val = (val << 8) + tlv->value[i];
}
PrintAndLogEx(NORMAL, " value: %d (0x%08X)", val, val);
size_t n = (tlv->len * 2);
char *hex = calloc(n + 1, sizeof(uint8_t));
if (hex == NULL) {
return;
}
uint64_t val = asn1_value_integer(tlv, 0, tlv->len * 2);
PrintAndLogEx(NORMAL, " value: %" PRIu64 " (0x%X)", val, val);
hex_to_buffer((uint8_t*)hex, tlv->value, tlv->len, tlv->len, 0, 0, false);
// results for MPI actions
bool ret = false;
// container of big number
mbedtls_mpi N;
mbedtls_mpi_init(&N);
MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&N, 16, hex));
char s[600] = {0};
size_t slen = 0;
MBEDTLS_MPI_CHK(mbedtls_mpi_write_string(&N, 10, s, sizeof(s), &slen));
if (slen > 0) {
PrintAndLogEx(NORMAL, "%*s value: %s", (level ), "", s);
}
cleanup:
mbedtls_mpi_free(&N);
free(hex);
}
static char *asn1_oid_description(const char *oid, bool with_group_desc) {
@ -343,7 +331,7 @@ static void asn1_tag_dump_object_id(const struct tlv *tlv, const struct asn1_tag
char pstr[300];
mbedtls_oid_get_numeric_string(pstr, sizeof(pstr), &asn1_buf);
PrintAndLogEx(NORMAL, "%*s %s" NOLF, (level * 4), " ", pstr);
PrintAndLogEx(NORMAL, "%*s %s" NOLF, (level), " ", pstr);
char *jsondesc = asn1_oid_description(pstr, true);
if (jsondesc) {