123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327 |
- #include "ecdsa_utils.h"
- #include <string.h>
- #define DER_INTEGER_MAX_LEN 0x7F
- #define DER_SEQUENCE_MAX_LEN 0x7F
- #define ASN1_DER_TAG_OFFSET 0
- #define ASN1_DER_LEN_OFFSET 1
- #define ASN1_DER_VAL_OFFSET 2
- #define DER_TAG_INTEGER 0x02
- #define DER_TAG_SEQUENCE 0x30
- #define DER_UINT_MASK 0x80
- static size_t encode_der_integer(const uint8_t* data, size_t data_len,
- uint8_t* out_buf, size_t out_buf_len)
- {
-
- const uint8_t* const out_end = out_buf + out_buf_len - 1;
-
- uint8_t* const tag_field = &out_buf[ASN1_DER_TAG_OFFSET];
- uint8_t* const length_field = &out_buf[ASN1_DER_LEN_OFFSET];
- uint8_t* const integer_field_start = &out_buf[ASN1_DER_VAL_OFFSET];
-
- uint8_t* integer_field_cur = integer_field_start;
-
- const uint8_t* cur_data = data;
- const uint8_t* const data_end = data + data_len;
-
- if (data_len == 0) {
- return 0;
- }
-
- for(; cur_data < (data_end - 1); cur_data++) {
- if (*cur_data != 0x00) {
- break;
- }
- }
-
- if (*cur_data & DER_UINT_MASK) {
- integer_field_cur++;
- }
-
- const size_t write_length = data_end - cur_data;
-
- if ((integer_field_cur + write_length - 1) > out_end) {
-
- return 0;
- }
-
- const size_t integer_len = (integer_field_cur + write_length) - integer_field_start;
- if (integer_len > DER_INTEGER_MAX_LEN) {
-
- return 0;
- }
-
- memcpy(integer_field_cur, cur_data, write_length);
- *tag_field = DER_TAG_INTEGER;
- *length_field = integer_len;
-
- if (integer_field_cur != integer_field_start) {
- *integer_field_start = 0x00;
- }
- return integer_len + ASN1_DER_VAL_OFFSET;
- }
- bool ecdsa_rs_to_asn1_integers(const uint8_t* r, const uint8_t* s, size_t rs_len,
- uint8_t* asn_sig, size_t* asn_sig_len)
- {
- if (r == NULL || s == NULL || asn_sig == NULL || asn_sig_len == NULL) {
-
- return false;
- }
-
- const size_t out_len_r = encode_der_integer(r, rs_len, asn_sig, *asn_sig_len);
- if (out_len_r == 0) {
-
- return false;
- }
- uint8_t* const s_start = asn_sig + out_len_r;
- const size_t s_len = *asn_sig_len - out_len_r;
-
- const size_t out_len_s = encode_der_integer(s, rs_len, s_start, s_len);
- if (out_len_s == 0) {
-
- return false;
- }
- *asn_sig_len = out_len_r + out_len_s;
- return true;
- }
- bool ecdsa_rs_to_asn1_signature(const uint8_t* r, const uint8_t* s, size_t rs_len,
- uint8_t* asn_sig, size_t* asn_sig_len)
- {
- if (r == NULL || s == NULL || asn_sig == NULL || asn_sig_len == NULL) {
-
- return false;
- }
- if (*asn_sig_len < ASN1_DER_VAL_OFFSET) {
-
- return false;
- }
-
- uint8_t* const tag_field = &asn_sig[ASN1_DER_TAG_OFFSET];
- uint8_t* const length_field = &asn_sig[ASN1_DER_LEN_OFFSET];
- uint8_t* const value_field_start = &asn_sig[ASN1_DER_VAL_OFFSET];
-
- size_t integers_len = *asn_sig_len - ASN1_DER_VAL_OFFSET;
- if (!ecdsa_rs_to_asn1_integers(r, s, rs_len, value_field_start, &integers_len)) {
-
- return false;
- }
- if (integers_len > DER_SEQUENCE_MAX_LEN) {
-
- return false;
- }
-
- *tag_field = DER_TAG_SEQUENCE;
- *length_field = integers_len;
- *asn_sig_len = integers_len + ASN1_DER_VAL_OFFSET;
- return true;
- }
- static size_t decode_asn1_uint(const uint8_t* asn1, size_t asn1_len,
- uint8_t* out_int, size_t* out_int_len)
- {
- if (asn1_len < (ASN1_DER_VAL_OFFSET + 1)) {
-
- return 0;
- }
-
- const uint8_t* const asn1_end = asn1 + asn1_len;
-
- const uint8_t* const tag_field = &asn1[ASN1_DER_TAG_OFFSET];
- const uint8_t* const length_field = &asn1[ASN1_DER_LEN_OFFSET];
- if (*tag_field != DER_TAG_INTEGER) {
-
- return 0;
- }
- if (*length_field == 0 || *length_field > DER_INTEGER_MAX_LEN) {
-
- return 0;
- }
- uint8_t integer_length = *length_field;
- const uint8_t* integer_field_cur = &asn1[ASN1_DER_VAL_OFFSET];
- if ((integer_field_cur + integer_length - 1) > (asn1_end - 1)) {
-
- return 0;
- }
-
- if (integer_length > 1) {
- if (*integer_field_cur == 0x00) {
-
- integer_length--;
- integer_field_cur++;
- }
- if (*integer_field_cur == 0x00) {
-
- return 0;
- }
- }
- if (integer_length > *out_int_len) {
-
- return 0;
- }
-
- const size_t padding = *out_int_len - integer_length;
- memset(out_int, 0, padding);
- memcpy(out_int + padding, integer_field_cur, integer_length);
- *out_int_len = integer_length;
-
- return integer_field_cur + integer_length - tag_field;
- }
- bool asn1_to_ecdsa_rs_sep(const uint8_t* asn1, size_t asn1_len,
- uint8_t* r, size_t* r_len,
- uint8_t* s, size_t* s_len)
- {
- if (asn1 == NULL || r == NULL || r_len == NULL || s == NULL || s_len == NULL) {
-
- return false;
- }
-
- const size_t consumed_r = decode_asn1_uint(asn1, asn1_len, r, r_len);
- if (consumed_r == 0) {
-
- return false;
- }
- const uint8_t* const asn1_s = asn1 + consumed_r;
- const size_t asn1_s_len = asn1_len - consumed_r;
-
- const size_t consumed_s = decode_asn1_uint(asn1_s, asn1_s_len, s, s_len);
- if (consumed_s == 0) {
-
- return false;
- }
- return true;
- }
- bool asn1_to_ecdsa_rs(const uint8_t* asn1, size_t asn1_len,
- uint8_t* rs, size_t rs_len)
- {
- if (asn1 == NULL || rs == NULL || rs_len == 0) {
-
- return false;
- }
- if ((rs_len % 2) != 0) {
-
- return false;
- }
- const size_t component_length = rs_len / 2;
- size_t r_len = component_length;
- size_t s_len = component_length;
- return asn1_to_ecdsa_rs_sep(asn1, asn1_len, rs, &r_len, rs + component_length, &s_len);
- }
|