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Add support for dynamic VIDPID via PHY.
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Signed-off-by: Pol Henarejos <[email protected]>
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@polhenarejos
polhenarejos committed Sep 18, 2024
1 parent 2fca445 commit cf5dbc9
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Showing 3 changed files with 62 additions and 48 deletions.
55 changes: 52 additions & 3 deletions src/fido/cbor_config.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
#include "mbedtls/ecdh.h"
#include "mbedtls/chachapoly.h"
#include "mbedtls/sha256.h"
#include "file.h"

extern uint8_t keydev_dec[32];
extern bool has_keydev_dec;
Expand All @@ -35,7 +36,7 @@ int cbor_config(const uint8_t *data, size_t len) {
CborParser parser;
CborValue map;
CborError error = CborNoError;
uint64_t subcommand = 0, pinUvAuthProtocol = 0, vendorCommandId = 0, newMinPinLength = 0;
uint64_t subcommand = 0, pinUvAuthProtocol = 0, vendorCommandId = 0, newMinPinLength = 0, vendorParam = 0;
CborByteString pinUvAuthParam = { 0 }, vendorAutCt = { 0 };
CborCharString minPinLengthRPIDs[32] = { 0 };
size_t resp_size = 0, raw_subpara_len = 0, minPinLengthRPIDs_len = 0;
Expand Down Expand Up @@ -65,7 +66,7 @@ int cbor_config(const uint8_t *data, size_t len) {
raw_subpara = (uint8_t *) cbor_value_get_next_byte(&_f1);
CBOR_PARSE_MAP_START(_f1, 2)
{
if (subcommand == 0x7f) {
if (subcommand == 0x7f) { // Config Aut
CBOR_FIELD_GET_UINT(subpara, 2);
if (subpara == 0x01) {
CBOR_FIELD_GET_UINT(vendorCommandId, 2);
Expand All @@ -74,7 +75,7 @@ int cbor_config(const uint8_t *data, size_t len) {
CBOR_FIELD_GET_BYTES(vendorAutCt, 2);
}
}
else if (subcommand == 0x03) {
else if (subcommand == 0x03) { // Extensions
CBOR_FIELD_GET_UINT(subpara, 2);
if (subpara == 0x01) {
CBOR_FIELD_GET_UINT(newMinPinLength, 2);
Expand All @@ -94,6 +95,15 @@ int cbor_config(const uint8_t *data, size_t len) {
CBOR_FIELD_GET_BOOL(forceChangePin, 2);
}
}
else if (subcommand == 0x1B) { // PHY
CBOR_FIELD_GET_UINT(subpara, 2);
if (subpara == 0x01) {
CBOR_FIELD_GET_UINT(vendorCommandId, 2);
}
else if (subpara == 0x02) {
CBOR_FIELD_GET_UINT(vendorParam, 2);
}
}
}
CBOR_PARSE_MAP_END(_f1, 2);
raw_subpara_len = cbor_value_get_next_byte(&_f1) - raw_subpara;
Expand Down Expand Up @@ -212,6 +222,45 @@ int cbor_config(const uint8_t *data, size_t len) {
set_opts(get_opts() | FIDO2_OPT_EA);
goto err;
}
#ifndef ENABLE_EMULATION
else if (subcommand == 0x1B) {
uint8_t tmp[PHY_MAX_SIZE];
memset(tmp, 0, sizeof(tmp));
uint16_t opts = 0;
if (file_has_data(ef_phy)) {
memcpy(tmp, file_get_data(ef_phy), MIN(sizeof(tmp), file_get_size(ef_phy)));
if (file_get_size(ef_phy) >= 8) {
opts = (tmp[PHY_OPTS] << 8) | tmp[PHY_OPTS + 1];
}
}
if (vendorCommandId == CTAP_CONFIG_PHY_VIDPID) {
if (vendorParam != 0) {
uint8_t d[4] = { (vendorParam >> 24) & 0xFF, (vendorParam >> 16) & 0xFF, (vendorParam >> 8) & 0xFF, vendorParam & 0xFF };
memcpy(tmp + PHY_VID, d, sizeof(d));
opts |= PHY_OPT_VPID;
}
else {
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
}
}
else if (vendorCommandId == CTAP_CONFIG_PHY_OPTS) {
if (vendorParam != 0) {
uint16_t opt = (uint16_t)vendorParam;
opts = (opts & ~PHY_OPT_MASK) | (opt & PHY_OPT_MASK);
}
else {
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
}
}
else {
CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);
}
tmp[PHY_OPTS] = opts >> 8;
tmp[PHY_OPTS + 1] = opts & 0xff;
file_put_data(ef_phy, tmp, sizeof(tmp));
low_flash_available();
}
#endif
else {
CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);
}
Expand Down
53 changes: 8 additions & 45 deletions src/fido/cbor_vendor.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,14 +37,7 @@ int mse_decrypt_ct(uint8_t *data, size_t len) {
mbedtls_chachapoly_context chatx;
mbedtls_chachapoly_init(&chatx);
mbedtls_chachapoly_setkey(&chatx, mse.key_enc + 12);
int ret = mbedtls_chachapoly_auth_decrypt(&chatx,
len - 16,
mse.key_enc,
mse.Qpt,
65,
data + len - 16,
data,
data);
int ret = mbedtls_chachapoly_auth_decrypt(&chatx, len - 16, mse.key_enc, mse.Qpt, 65, data + len - 16, data, data);
mbedtls_chachapoly_free(&chatx);
return ret;
}
Expand Down Expand Up @@ -112,8 +105,7 @@ int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {
CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 1));
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));

CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, file_get_data(ef_keydev_enc),
file_get_size(ef_keydev_enc)));
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder, file_get_data(ef_keydev_enc), file_get_size(ef_keydev_enc)));
}
else if (vendorCmd == 0x02) {
if (vendorParam.present == false) {
Expand All @@ -140,11 +132,7 @@ int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {
mbedtls_ecdh_context hkey;
mbedtls_ecdh_init(&hkey);
mbedtls_ecdh_setup(&hkey, MBEDTLS_ECP_DP_SECP256R1);
int ret = mbedtls_ecdh_gen_public(&hkey.ctx.mbed_ecdh.grp,
&hkey.ctx.mbed_ecdh.d,
&hkey.ctx.mbed_ecdh.Q,
random_gen,
NULL);
int ret = mbedtls_ecdh_gen_public(&hkey.ctx.mbed_ecdh.grp, &hkey.ctx.mbed_ecdh.d, &hkey.ctx.mbed_ecdh.Q, random_gen, NULL);
mbedtls_mpi_lset(&hkey.ctx.mbed_ecdh.Qp.Z, 1);
if (ret != 0) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
Expand All @@ -160,37 +148,19 @@ int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {

uint8_t buf[MBEDTLS_ECP_MAX_BYTES];
size_t olen = 0;
ret = mbedtls_ecp_point_write_binary(&hkey.ctx.mbed_ecdh.grp,
&hkey.ctx.mbed_ecdh.Qp,
MBEDTLS_ECP_PF_UNCOMPRESSED,
&olen,
mse.Qpt,
sizeof(mse.Qpt));
ret = mbedtls_ecp_point_write_binary(&hkey.ctx.mbed_ecdh.grp, &hkey.ctx.mbed_ecdh.Qp, MBEDTLS_ECP_PF_UNCOMPRESSED, &olen, mse.Qpt,sizeof(mse.Qpt));
if (ret != 0) {
mbedtls_ecdh_free(&hkey);
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}

ret = mbedtls_ecdh_calc_secret(&hkey,
&olen,
buf,
MBEDTLS_ECP_MAX_BYTES,
random_gen,
NULL);
ret = mbedtls_ecdh_calc_secret(&hkey, &olen, buf, MBEDTLS_ECP_MAX_BYTES, random_gen, NULL);
if (ret != 0) {
mbedtls_ecdh_free(&hkey);
mbedtls_platform_zeroize(buf, sizeof(buf));
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
ret = mbedtls_hkdf(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
NULL,
0,
buf,
olen,
mse.Qpt,
sizeof(mse.Qpt),
mse.key_enc,
sizeof(mse.key_enc));
ret = mbedtls_hkdf(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), NULL, 0, buf, olen, mse.Qpt, sizeof(mse.Qpt), mse.key_enc, sizeof(mse.key_enc));
mbedtls_platform_zeroize(buf, sizeof(buf));
if (ret != 0) {
mbedtls_ecdh_free(&hkey);
Expand Down Expand Up @@ -248,22 +218,15 @@ int cbor_vendor_generic(uint8_t cmd, const uint8_t *data, size_t len) {
}
mbedtls_x509write_csr ctx;
mbedtls_x509write_csr_init(&ctx);
snprintf((char *) buffer,
sizeof(buffer),
"C=ES,O=Pico Keys,OU=Authenticator Attestation,CN=Pico Fido EE Serial %s", pico_serial_str);
snprintf((char *) buffer, sizeof(buffer), "C=ES,O=Pico Keys,OU=Authenticator Attestation,CN=Pico Fido EE Serial %s", pico_serial_str);
mbedtls_x509write_csr_set_subject_name(&ctx, (char *) buffer);
mbedtls_pk_context key;
mbedtls_pk_init(&key);
mbedtls_pk_setup(&key, mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY));
key.pk_ctx = &ekey;
mbedtls_x509write_csr_set_key(&ctx, &key);
mbedtls_x509write_csr_set_md_alg(&ctx, MBEDTLS_MD_SHA256);
mbedtls_x509write_csr_set_extension(&ctx,
"\x2B\x06\x01\x04\x01\x82\xE5\x1C\x01\x01\x04",
0xB,
0,
aaguid,
sizeof(aaguid));
mbedtls_x509write_csr_set_extension(&ctx, "\x2B\x06\x01\x04\x01\x82\xE5\x1C\x01\x01\x04", 0xB, 0, aaguid, sizeof(aaguid));
ret = mbedtls_x509write_csr_der(&ctx, buffer, sizeof(buffer), random_gen, NULL);
mbedtls_ecdsa_free(&ekey);
if (ret <= 0) {
Expand Down
2 changes: 2 additions & 0 deletions src/fido/ctap.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,8 @@ typedef struct {

#define CTAP_CONFIG_AUT_ENABLE 0x03e43f56b34285e2
#define CTAP_CONFIG_AUT_DISABLE 0x1831a40f04a25ed9
#define CTAP_CONFIG_PHY_VIDPID 0x6fcb19b0cbe3acfa
#define CTAP_CONFIG_PHY_OPTS 0x969f3b09eceb805f

#define CTAP_VENDOR_CBOR (CTAPHID_VENDOR_FIRST + 1)

Expand Down

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