client/src/crypto/asn1utils.c

   1 //-----------------------------------------------------------------------------
   2 // Copyright (C) 2018 Merlok
   3 //
   4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   5 // at your option, any later version. See the LICENSE.txt file for the text of
   6 // the license.
   7 //-----------------------------------------------------------------------------
   8 // asn.1 utils
   9 //-----------------------------------------------------------------------------
  10
  11 #include "asn1utils.h"
  12 #include <ctype.h>
  13 #include <stdlib.h>
  14 #include <mbedtls/asn1.h>
  15 #include "ui.h"  // Print...
  16 #include "emv/tlv.h"
  17 #include "asn1dump.h"
  18 #include "util.h"
  19
  20 int ecdsa_asn1_get_signature(uint8_t *signature, size_t signaturelen, uint8_t *rval, uint8_t *sval) {
  21     if (!signature || !signaturelen || !rval || !sval)
  22         return PM3_EINVARG;
  23
  24     int res = PM3_SUCCESS;
  25     unsigned char *p = signature;
  26     const unsigned char *end = p + signaturelen;
  27     size_t len;
  28     mbedtls_mpi xmpi;
  29
  30     if ((res = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) == 0) {
  31         mbedtls_mpi_init(&xmpi);
  32         res = mbedtls_asn1_get_mpi(&p, end, &xmpi);
  33         if (res) {
  34             mbedtls_mpi_free(&xmpi);
  35             goto exit;
  36         }
  37
  38         res = mbedtls_mpi_write_binary(&xmpi, rval, 32);
  39         mbedtls_mpi_free(&xmpi);
  40         if (res)
  41             goto exit;
  42
  43         mbedtls_mpi_init(&xmpi);
  44         res = mbedtls_asn1_get_mpi(&p, end, &xmpi);
  45         if (res) {
  46             mbedtls_mpi_free(&xmpi);
  47             goto exit;
  48         }
  49
  50         res = mbedtls_mpi_write_binary(&xmpi, sval, 32);
  51         mbedtls_mpi_free(&xmpi);
  52         if (res)
  53             goto exit;
  54
  55         // check size
  56         if (end != p)
  57             return PM3_ESOFT;
  58     }
  59
  60 exit:
  61     return res;
  62 }
  63
  64 static void asn1_print_cb(void *data, const struct tlv *tlv, int level, bool is_leaf) {
  65     bool candump = true;
  66     asn1_tag_dump(tlv, level, &candump);
  67     if (is_leaf && candump) {
  68         print_buffer(tlv->value, tlv->len, level + 1);
  69     }
  70 }
  71
  72 int asn1_print(uint8_t *asn1buf, size_t asn1buflen, const char *indent) {
  73
  74     struct tlvdb *t = tlvdb_parse_multi(asn1buf, asn1buflen);
  75     if (t) {
  76         tlvdb_visit(t, asn1_print_cb, NULL, 0);
  77         tlvdb_free(t);
  78     } else {
  79         PrintAndLogEx(ERR, "Can't parse data as TLV tree");
  80         return PM3_ESOFT;
  81     }
  82
  83     return PM3_SUCCESS;
  84 }
  85
  86