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Added support for silent authentication.

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Fixes #91.

It requires FIDO22 credential protocol, meaning that old credentials have to be reissued.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2025-02-08 15:00:12 +01:00
parent 353d782970
commit f43bc9701f
4 changed files with 140 additions and 64 deletions
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102
src/fido/cbor_get_assertion.c
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@@ -279,6 +279,8 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
}
}
bool silent = (up == false && uv == false);
if (allowList_len > 0) {
for (size_t e = 0; e < allowList_len; e++) {
if (allowList[e].type.present == false || allowList[e].id.present == false) {
@@ -288,7 +290,6 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
continue;
}
if (credential_load(allowList[e].id.data, allowList[e].id.len, rp_id_hash, &creds[creds_len]) != 0) {
CBOR_FREE_BYTE_STRING(allowList[e].id);
credential_free(&creds[creds_len]);
}
else {
@@ -342,15 +343,32 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
}
}
if (numberOfCredentials == 0) {
CBOR_ERROR(CTAP2_ERR_NO_CREDENTIALS);
if (silent && allowList_len > 0) {
for (size_t e = 0; e < allowList_len; e++) {
if (allowList[e].type.present == false || allowList[e].id.present == false) {
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
}
if (strcmp(allowList[e].type.data, "public-key") != 0) {
continue;
}
if (credential_verify(allowList[e].id.data, allowList[e].id.len, rp_id_hash, true) == 0) {
numberOfCredentials++;
}
}
}
if (numberOfCredentials == 0) {
CBOR_ERROR(CTAP2_ERR_NO_CREDENTIALS);
}
}
for (int i = 0; i < numberOfCredentials; i++) {
for (int j = i + 1; j < numberOfCredentials; j++) {
if (creds[j].creation > creds[i].creation) {
Credential tmp = creds[j];
creds[j] = creds[i];
creds[i] = tmp;
if (!silent) {
for (int i = 0; i < numberOfCredentials; i++) {
for (int j = i + 1; j < numberOfCredentials; j++) {
if (creds[j].creation > creds[i].creation) {
Credential tmp = creds[j];
creds[j] = creds[i];
creds[i] = tmp;
}
}
}
}
@@ -380,8 +398,8 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
CBOR_ERROR(CTAP2_ERR_INVALID_OPTION);
}
if (up == false && uv == false) {
selcred = &creds[0];
if (silent && !resident) {
// Silent authentication, do nothing
}
else {
selcred = &creds[0];
@@ -410,16 +428,18 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
int ret = 0;
uint8_t largeBlobKey[32] = {0};
if (extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
ret = credential_derive_large_blob_key(selcred->id.data, selcred->id.len, largeBlobKey);
if (ret != 0) {
CBOR_ERROR(CTAP2_ERR_PROCESSING);
if (selcred) {
if (extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
ret = credential_derive_large_blob_key(selcred->id.data, selcred->id.len, largeBlobKey);
if (ret != 0) {
CBOR_ERROR(CTAP2_ERR_PROCESSING);
}
}
}
size_t ext_len = 0;
uint8_t ext[512] = {0};
if (extensions.present == true) {
if (selcred && extensions.present == true) {
cbor_encoder_init(&encoder, ext, sizeof(ext), 0);
int l = 0;
if (options.up == pfalse) {
@@ -530,32 +550,39 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
const mbedtls_md_info_t *md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
mbedtls_ecdsa_context ekey;
mbedtls_ecdsa_init(&ekey);
ret = fido_load_key((int)selcred->curve, selcred->id.data, &ekey);
if (ret != 0) {
if (derive_key(rp_id_hash, false, selcred->id.data, MBEDTLS_ECP_DP_SECP256R1, &ekey) != 0) {
mbedtls_ecdsa_free(&ekey);
CBOR_ERROR(CTAP1_ERR_OTHER);
}
}
if (ekey.grp.id == MBEDTLS_ECP_DP_SECP384R1) {
md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA384);
}
else if (ekey.grp.id == MBEDTLS_ECP_DP_SECP521R1) {
md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA512);
}
ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
size_t olen = 0;
ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
if (selcred) {
ret = fido_load_key((int)selcred->curve, selcred->id.data, &ekey);
if (ret != 0) {
if (derive_key(rp_id_hash, false, selcred->id.data, MBEDTLS_ECP_DP_SECP256R1, &ekey) != 0) {
mbedtls_ecdsa_free(&ekey);
CBOR_ERROR(CTAP1_ERR_OTHER);
}
}
if (ekey.grp.id == MBEDTLS_ECP_DP_SECP384R1) {
md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA384);
}
else if (ekey.grp.id == MBEDTLS_ECP_DP_SECP521R1) {
md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA512);
}
ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
}
else {
// Bogus signature
olen = 64;
memset(sig, 0x0B, olen);
}
mbedtls_ecdsa_free(&ekey);
uint8_t lfields = 3;
if (selcred->opts.present == true && selcred->opts.rk == ptrue) {
if (selcred && selcred->opts.present == true && selcred->opts.rk == ptrue) {
lfields++;
}
if (numberOfCredentials > 1 && next == false) {
lfields++;
}
if (extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
if (selcred && extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
lfields++;
}
cbor_encoder_init(&encoder, ctap_resp->init.data + 1, CTAP_MAX_CBOR_PAYLOAD, 0);
@@ -564,7 +591,12 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));
CBOR_CHECK(cbor_encoder_create_map(&mapEncoder, &mapEncoder2, 2));
CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "id"));
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, selcred->id.data, selcred->id.len));
if (selcred) {
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, selcred->id.data, selcred->id.len));
}
else {
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, (uint8_t *)"\x00\x01\x00\x01\x00\x01\x00\x01\x00\x01\x00\x01\x00\x01\x00\x01", 16));
}
CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "type"));
CBOR_CHECK(cbor_encode_text_stringz(&mapEncoder2, "public-key"));
CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2));
@@ -574,7 +606,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x03));
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, sig, olen));
if (selcred->opts.present == true && selcred->opts.rk == ptrue) {
if (selcred && selcred->opts.present == true && selcred->opts.rk == ptrue) {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x04));
uint8_t lu = 1;
if (numberOfCredentials > 1 && allowList_len == 0) {
@@ -605,7 +637,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x05));
CBOR_CHECK(cbor_encode_uint(&mapEncoder, numberOfCredentials));
}
if (extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
if (selcred && extensions.largeBlobKey == ptrue && selcred->extensions.largeBlobKey == ptrue) {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x07));
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, largeBlobKey, sizeof(largeBlobKey)));
}