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Fix returning ecdsa response for keys > 512 bits.

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In that case, TLV shall contain 81 length.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2023-02-04 20:26:54 +01:00
parent 7b17cc7b49
commit b300ed87f3
1 changed files with 11 additions and 6 deletions
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17
src/openpgp/openpgp.c
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@@ -1210,15 +1210,20 @@ void make_rsa_response(mbedtls_rsa_context *rsa) {
}
void make_ecdsa_response(mbedtls_ecdsa_context *ecdsa) {
uint8_t pt[MBEDTLS_ECP_MAX_PT_LEN];
size_t plen = 0;
memcpy(res_APDU, "\x7f\x49\x00", 3);
res_APDU_size = 3;
mbedtls_ecp_point_write_binary(&ecdsa->grp, &ecdsa->Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &plen, pt, sizeof(pt));
res_APDU[res_APDU_size++] = 0x7f;
res_APDU[res_APDU_size++] = 0x49;
if (plen >= 128)
res_APDU[res_APDU_size++] = 0x81;
res_APDU[res_APDU_size++] = plen + (plen >= 128 ? 3 : 2);
res_APDU[res_APDU_size++] = 0x86;
res_APDU[res_APDU_size++] = 0;
mbedtls_ecp_point_write_binary(&ecdsa->grp, &ecdsa->Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &plen, res_APDU + res_APDU_size, 4096);
if (plen >= 128)
res_APDU[res_APDU_size++] = 0x81;
res_APDU[res_APDU_size++] = plen;
memcpy(res_APDU + res_APDU_size, pt, plen);
res_APDU_size += plen;
res_APDU[4] = plen;
res_APDU[2] = plen + 2;
}
static int cmd_keypair_gen() {