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check FIDO2 credential IDs in U2F

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This commit is contained in:
Conor Patrick 2019-10-08 15:32:20 -04:00
parent ff88660027
commit 82551c0b1c
2 changed files with 36 additions and 17 deletions
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41
fido2/u2f.c
View File

@ -26,6 +26,7 @@ static int16_t u2f_authenticate(struct u2f_authenticate_request * req, uint8_t c
int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len); int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len);
void u2f_reset_response(); void u2f_reset_response();
void make_auth_tag(uint8_t * rpIdHash, uint8_t * nonce, uint32_t count, uint8_t * tag);
static CTAP_RESPONSE * _u2f_resp = NULL; static CTAP_RESPONSE * _u2f_resp = NULL;
@ -160,9 +161,9 @@ static void dump_signature_der(uint8_t * sig)
len = ctap_encode_der_sig(sig, sigder); len = ctap_encode_der_sig(sig, sigder);
u2f_response_writeback(sigder, len); u2f_response_writeback(sigder, len);
} }
static int8_t u2f_load_key(struct u2f_key_handle * kh, uint8_t * appid) static int8_t u2f_load_key(struct u2f_key_handle * kh, uint8_t khl, uint8_t * appid)
{ {
crypto_ecc256_load_key((uint8_t*)kh, U2F_KEY_HANDLE_SIZE, NULL, 0); crypto_ecc256_load_key((uint8_t*)kh, khl, NULL, 0);
return 0; return 0;
} }
@ -187,21 +188,40 @@ int8_t u2f_new_keypair(struct u2f_key_handle * kh, uint8_t * appid, uint8_t * pu
// Return 1 if authenticate, 0 if not. // Return 1 if authenticate, 0 if not.
int8_t u2f_authenticate_credential(struct u2f_key_handle * kh, uint8_t * appid) int8_t u2f_authenticate_credential(struct u2f_key_handle * kh, uint8_t key_handle_len, uint8_t * appid)
{ {
printf1(TAG_U2F, "checked CRED SIZE %d. (FIDO2: %d)\n", key_handle_len, sizeof(CredentialId));
uint8_t tag[U2F_KEY_HANDLE_TAG_SIZE]; uint8_t tag[U2F_KEY_HANDLE_TAG_SIZE];
if (key_handle_len == sizeof(CredentialId))
{
printf1(TAG_U2F, "FIDO2 key handle detected.\n");
CredentialId * cred = (CredentialId *) kh;
// FIDO2 credential.
if (memcmp(cred->rpIdHash, appid, 32) != 0)
{
printf1(TAG_U2F, "APPID does not match rpIdHash.\n");
return 0;
}
make_auth_tag(appid, cred->nonce, cred->count, tag);
if (memcmp(cred->tag, tag, CREDENTIAL_TAG_SIZE) == 0){
return 1;
}
}else if (key_handle_len == U2F_KEY_HANDLE_KEY_SIZE)
{
u2f_make_auth_tag(kh, appid, tag); u2f_make_auth_tag(kh, appid, tag);
if (memcmp(kh->tag, tag, U2F_KEY_HANDLE_TAG_SIZE) == 0) if (memcmp(kh->tag, tag, U2F_KEY_HANDLE_TAG_SIZE) == 0)
{ {
return 1; return 1;
} }
else }
{
printf1(TAG_U2F, "key handle + appid not authentic\n"); printf1(TAG_U2F, "key handle + appid not authentic\n");
printf1(TAG_U2F, "calc tag: \n"); dump_hex1(TAG_U2F,tag, U2F_KEY_HANDLE_TAG_SIZE); printf1(TAG_U2F, "calc tag: \n"); dump_hex1(TAG_U2F,tag, U2F_KEY_HANDLE_TAG_SIZE);
printf1(TAG_U2F, "inp tag: \n"); dump_hex1(TAG_U2F,kh->tag, U2F_KEY_HANDLE_TAG_SIZE); printf1(TAG_U2F, "inp tag: \n"); dump_hex1(TAG_U2F,kh->tag, U2F_KEY_HANDLE_TAG_SIZE);
return 0;
}
} }
@ -216,7 +236,7 @@ static int16_t u2f_authenticate(struct u2f_authenticate_request * req, uint8_t c
if (control == U2F_AUTHENTICATE_CHECK) if (control == U2F_AUTHENTICATE_CHECK)
{ {
printf1(TAG_U2F, "CHECK-ONLY\r\n"); printf1(TAG_U2F, "CHECK-ONLY\r\n");
if (u2f_authenticate_credential(&req->kh, req->app)) if (u2f_authenticate_credential(&req->kh, req->khl, req->app))
{ {
return U2F_SW_CONDITIONS_NOT_SATISFIED; return U2F_SW_CONDITIONS_NOT_SATISFIED;
} }
@ -227,9 +247,8 @@ static int16_t u2f_authenticate(struct u2f_authenticate_request * req, uint8_t c
} }
if ( if (
(control != U2F_AUTHENTICATE_SIGN && control != U2F_AUTHENTICATE_SIGN_NO_USER) || (control != U2F_AUTHENTICATE_SIGN && control != U2F_AUTHENTICATE_SIGN_NO_USER) ||
req->khl != U2F_KEY_HANDLE_SIZE || (!u2f_authenticate_credential(&req->kh, req->khl, req->app)) || // Order of checks is important
(!u2f_authenticate_credential(&req->kh, req->app)) || // Order of checks is important u2f_load_key(&req->kh, req->khl, req->app) != 0
u2f_load_key(&req->kh, req->app) != 0
) )
{ {

2
fido2/u2f.h
View File

@ -103,7 +103,7 @@ void u2f_request(struct u2f_request_apdu* req, CTAP_RESPONSE * resp);
// @len data length // @len data length
void u2f_request_nfc(uint8_t * header, uint8_t * data, int datalen, CTAP_RESPONSE * resp); void u2f_request_nfc(uint8_t * header, uint8_t * data, int datalen, CTAP_RESPONSE * resp);
int8_t u2f_authenticate_credential(struct u2f_key_handle * kh, uint8_t * appid); int8_t u2f_authenticate_credential(struct u2f_key_handle * kh, uint8_t key_handle_len, uint8_t * appid);
int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len); int8_t u2f_response_writeback(const uint8_t * buf, uint16_t len);
void u2f_reset_response(); void u2f_reset_response();