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ctap.c
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ctap.c
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// Copyright 2019 SoloKeys Developers
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cbor.h"
#include "ctap.h"
#include "u2f.h"
#include "ctaphid.h"
#include "ctap_parse.h"
#include "ctap_errors.h"
#include "cose_key.h"
#include "crypto.h"
#include "util.h"
#include "log.h"
#include "device.h"
#include APP_CONFIG
#include "wallet.h"
#include "extensions.h"
#include "device.h"
#include "data_migration.h"
uint8_t PIN_TOKEN[PIN_TOKEN_SIZE];
uint8_t KEY_AGREEMENT_PUB[64];
static uint8_t KEY_AGREEMENT_PRIV[32];
static int8_t PIN_BOOT_ATTEMPTS_LEFT = PIN_BOOT_ATTEMPTS;
AuthenticatorState STATE;
static void ctap_reset_key_agreement();
struct _getAssertionState getAssertionState;
// Generate a mask to keep the confidentiality of the "metadata" field in the credential ID.
// Mask = hmac(device-secret, 14-random-bytes-in-credential-id)
// Masked_output = Mask ^ metadata
static void add_masked_metadata_for_credential(CredentialId * credential, uint32_t metadata){
uint8_t mask[32];
crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY, 0, mask);
crypto_sha256_update(credential->entropy.nonce, CREDENTIAL_NONCE_SIZE - 4);
crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY,0, mask);
credential->entropy.metadata.value = *((uint32_t*)mask) ^ metadata;
}
static uint32_t read_metadata_from_masked_credential(CredentialId * credential){
uint8_t mask[32];
crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY, 0, mask);
crypto_sha256_update(credential->entropy.nonce, CREDENTIAL_NONCE_SIZE - 4);
crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY,0, mask);
return credential->entropy.metadata.value ^ *((uint32_t*)mask);
}
static uint32_t read_cred_protect_from_masked_credential(CredentialId * credential)
{
return read_metadata_from_masked_credential(credential) & 0xffffU;
}
static int32_t read_cose_alg_from_masked_credential(CredentialId * credential)
{
uint8_t alg = (read_metadata_from_masked_credential(credential) >> 16) & 0xffU;
switch (alg)
{
default: // what else?
case CREDID_ALG_ES256:
return COSE_ALG_ES256;
case CREDID_ALG_EDDSA:
return COSE_ALG_EDDSA;
}
}
static uint8_t check_credential_metadata(CredentialId * credential, uint8_t is_verified, uint8_t is_from_credid_list)
{
uint32_t cred_protect = read_cred_protect_from_masked_credential(credential);
switch (cred_protect){
case EXT_CRED_PROTECT_OPTIONAL_WITH_CREDID:
if (!is_from_credid_list) {
if (!is_verified)
{
return CTAP2_ERR_NOT_ALLOWED;
}
}
break;
case EXT_CRED_PROTECT_REQUIRED:
if (!is_verified)
{
return CTAP2_ERR_NOT_ALLOWED;
}
break;
}
return 0;
}
static uint8_t verify_pin_auth_ex(uint8_t * pinAuth, uint8_t *buf, size_t len)
{
uint8_t hmac[32];
crypto_sha256_hmac_init(PIN_TOKEN, PIN_TOKEN_SIZE, hmac);
crypto_sha256_update(buf, len);
crypto_sha256_hmac_final(PIN_TOKEN, PIN_TOKEN_SIZE, hmac);
if (memcmp(pinAuth, hmac, 16) == 0)
{
return 0;
}
else
{
printf2(TAG_ERR,"Pin auth failed\n");
dump_hex1(TAG_ERR,pinAuth,16);
dump_hex1(TAG_ERR,hmac,16);
return CTAP2_ERR_PIN_AUTH_INVALID;
}
}
uint8_t verify_pin_auth(uint8_t * pinAuth, uint8_t * clientDataHash)
{
return verify_pin_auth_ex(pinAuth, clientDataHash, CLIENT_DATA_HASH_SIZE);
}
uint8_t ctap_get_info(CborEncoder * encoder)
{
int ret;
CborEncoder array;
CborEncoder map;
CborEncoder options;
CborEncoder pins;
uint8_t aaguid[16];
device_read_aaguid(aaguid);
ret = cbor_encoder_create_map(encoder, &map, 8);
check_ret(ret);
{
ret = cbor_encode_uint(&map, RESP_versions); // versions key
check_ret(ret);
{
ret = cbor_encoder_create_array(&map, &array, 3);
check_ret(ret);
{
ret = cbor_encode_text_stringz(&array, "U2F_V2");
check_ret(ret);
ret = cbor_encode_text_stringz(&array, "FIDO_2_0");
check_ret(ret);
ret = cbor_encode_text_stringz(&array, "FIDO_2_1_PRE");
check_ret(ret);
}
ret = cbor_encoder_close_container(&map, &array);
check_ret(ret);
}
ret = cbor_encode_uint(&map, RESP_extensions);
check_ret(ret);
{
ret = cbor_encoder_create_array(&map, &array, 2);
check_ret(ret);
{
ret = cbor_encode_text_stringz(&array, "credProtect");
check_ret(ret);
ret = cbor_encode_text_stringz(&array, "hmac-secret");
check_ret(ret);
}
ret = cbor_encoder_close_container(&map, &array);
check_ret(ret);
}
ret = cbor_encode_uint(&map, RESP_aaguid);
check_ret(ret);
{
ret = cbor_encode_byte_string(&map, aaguid, 16);
check_ret(ret);
}
ret = cbor_encode_uint(&map, RESP_options);
check_ret(ret);
{
ret = cbor_encoder_create_map(&map, &options,5);
check_ret(ret);
{
ret = cbor_encode_text_string(&options, "rk", 2);
check_ret(ret);
{
ret = cbor_encode_boolean(&options, 1); // Capable of storing keys locally
check_ret(ret);
}
ret = cbor_encode_text_string(&options, "up", 2);
check_ret(ret);
{
ret = cbor_encode_boolean(&options, 1); // Capable of testing user presence
check_ret(ret);
}
// NOT [yet] capable of verifying user
// Do not add option if UV isn't supported.
//
// ret = cbor_encode_text_string(&options, "uv", 2);
// check_ret(ret);
// {
// ret = cbor_encode_boolean(&options, 0);
// check_ret(ret);
// }
ret = cbor_encode_text_string(&options, "plat", 4);
check_ret(ret);
{
ret = cbor_encode_boolean(&options, 0); // Not attached to platform
check_ret(ret);
}
ret = cbor_encode_text_string(&options, "credMgmt", 8);
check_ret(ret);
{
ret = cbor_encode_boolean(&options, 1);
check_ret(ret);
}
ret = cbor_encode_text_string(&options, "clientPin", 9);
check_ret(ret);
{
ret = cbor_encode_boolean(&options, ctap_is_pin_set());
check_ret(ret);
}
}
ret = cbor_encoder_close_container(&map, &options);
check_ret(ret);
}
ret = cbor_encode_uint(&map, RESP_maxMsgSize);
check_ret(ret);
{
ret = cbor_encode_int(&map, CTAP_MAX_MESSAGE_SIZE);
check_ret(ret);
}
ret = cbor_encode_uint(&map, RESP_pinProtocols);
check_ret(ret);
{
ret = cbor_encoder_create_array(&map, &pins, 1);
check_ret(ret);
{
ret = cbor_encode_int(&pins, 1);
check_ret(ret);
}
ret = cbor_encoder_close_container(&map, &pins);
check_ret(ret);
}
ret = cbor_encode_uint(&map, 0x07); //maxCredentialCountInList
check_ret(ret);
{
ret = cbor_encode_uint(&map, ALLOW_LIST_MAX_SIZE);
check_ret(ret);
}
ret = cbor_encode_uint(&map, 0x08); // maxCredentialIdLength
check_ret(ret);
{
ret = cbor_encode_uint(&map, 128);
check_ret(ret);
}
}
ret = cbor_encoder_close_container(encoder, &map);
check_ret(ret);
return CTAP1_ERR_SUCCESS;
}
static int ctap_add_cose_key(CborEncoder * cose_key, uint8_t * x, uint8_t * y, uint8_t credtype, int32_t algtype)
{
int ret;
CborEncoder map;
ret = cbor_encoder_create_map(cose_key, &map, algtype != COSE_ALG_EDDSA? 5 : 4);
check_ret(ret);
{
ret = cbor_encode_int(&map, COSE_KEY_LABEL_KTY);
check_ret(ret);
ret = cbor_encode_int(&map, algtype != COSE_ALG_EDDSA? COSE_KEY_KTY_EC2 : COSE_KEY_KTY_OKP);
check_ret(ret);
}
{
ret = cbor_encode_int(&map, COSE_KEY_LABEL_ALG);
check_ret(ret);
ret = cbor_encode_int(&map, algtype);
check_ret(ret);
}
{
ret = cbor_encode_int(&map, COSE_KEY_LABEL_CRV);
check_ret(ret);
ret = cbor_encode_int(&map, algtype != COSE_ALG_EDDSA? COSE_KEY_CRV_P256: COSE_KEY_CRV_ED25519);
check_ret(ret);
}
{
ret = cbor_encode_int(&map, COSE_KEY_LABEL_X);
check_ret(ret);
ret = cbor_encode_byte_string(&map, x, 32);
check_ret(ret);
}
if (algtype != COSE_ALG_EDDSA)
{
ret = cbor_encode_int(&map, COSE_KEY_LABEL_Y);
check_ret(ret);
ret = cbor_encode_byte_string(&map, y, 32);
check_ret(ret);
}
ret = cbor_encoder_close_container(cose_key, &map);
check_ret(ret);
return 0;
}
static int ctap_generate_cose_key(CborEncoder * cose_key, uint8_t * hmac_input, int len, uint8_t credtype, int32_t algtype)
{
uint8_t x[32], y[32];
if (credtype != PUB_KEY_CRED_PUB_KEY)
{
printf2(TAG_ERR,"Error, pubkey credential type not supported\n");
return -1;
}
switch(algtype)
{
case COSE_ALG_ES256:
if (device_is_nfc() == NFC_IS_ACTIVE) device_set_clock_rate(DEVICE_LOW_POWER_FAST);
crypto_ecc256_derive_public_key(hmac_input, len, x, y);
if (device_is_nfc() == NFC_IS_ACTIVE) device_set_clock_rate(DEVICE_LOW_POWER_IDLE);
break;
case COSE_ALG_EDDSA:
if (device_is_nfc() == NFC_IS_ACTIVE) device_set_clock_rate(DEVICE_LOW_POWER_FAST);
crypto_ed25519_derive_public_key(hmac_input, len, x);
if (device_is_nfc() == NFC_IS_ACTIVE) device_set_clock_rate(DEVICE_LOW_POWER_IDLE);
break;
default:
printf2(TAG_ERR,"Error, COSE alg %d not supported\n", algtype);
return -1;
}
int ret = ctap_add_cose_key(cose_key, x, y, credtype, algtype);
check_ret(ret);
return 0;
}
void make_auth_tag(uint8_t * rpIdHash, uint8_t * nonce, uint32_t count, uint8_t * tag)
{
uint8_t hashbuf[32];
memset(hashbuf,0,sizeof(hashbuf));
crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY, 0, hashbuf);
crypto_sha256_update(rpIdHash, 32);
crypto_sha256_update(nonce, CREDENTIAL_NONCE_SIZE);
crypto_sha256_update((uint8_t*)&count, 4);
crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY,0,hashbuf);
memmove(tag, hashbuf, CREDENTIAL_TAG_SIZE);
}
void ctap_flush_state()
{
authenticator_write_state(&STATE);
}
static uint32_t auth_data_update_count(CTAP_authDataHeader * authData)
{
uint32_t count = ctap_atomic_count( 0 );
if (count == 0) // count 0 will indicate invalid token
{
count = ctap_atomic_count( 0 );
}
uint8_t * byte = (uint8_t*) &authData->signCount;
*byte++ = (count >> 24) & 0xff;
*byte++ = (count >> 16) & 0xff;
*byte++ = (count >> 8) & 0xff;
*byte++ = (count >> 0) & 0xff;
return count;
}
static void ctap_increment_rk_store()
{
STATE.rk_stored++;
ctap_flush_state();
}
static void ctap_decrement_rk_store()
{
STATE.rk_stored--;
ctap_flush_state();
}
// Return 1 if rk is valid, 0 if not.
static int ctap_rk_is_valid(CTAP_residentKey * rk)
{
return (rk->id.count > 0 && rk->id.count != 0xffffffff);
}
static int load_nth_valid_rk(int n, CTAP_residentKey * rk) {
int valid_count = 0;
unsigned int i;
for (i = 0; i < ctap_rk_size(); i++)
{
ctap_load_rk(i, rk);
if ( ctap_rk_is_valid(rk) ) {
if (valid_count == n) {
return i;
}
valid_count++;
}
}
return -1;
}
static int is_matching_rk(CTAP_residentKey * rk, CTAP_residentKey * rk2)
{
return (memcmp(rk->id.rpIdHash, rk2->id.rpIdHash, 32) == 0) &&
(memcmp(rk->user.id, rk2->user.id, rk->user.id_size) == 0) &&
(rk->user.id_size == rk2->user.id_size);
}
static int is_cred_id_matching_rk(CredentialId * credId, CTAP_residentKey * rk)
{
return (memcmp(credId, &rk->id, sizeof(CredentialId)) == 0);
}
static int ctap_make_extensions(CTAP_extensions * ext, uint8_t * ext_encoder_buf, unsigned int * ext_encoder_buf_size)
{
CborEncoder extensions;
int ret;
uint8_t extensions_used = 0;
uint8_t hmac_secret_output_is_valid = 0;
uint8_t hmac_secret_requested_is_valid = 0;
uint8_t cred_protect_is_valid = 0;
uint8_t hmac_secret_output[64];
uint8_t shared_secret[32];
uint8_t hmac[32];
uint8_t credRandom[32];
uint8_t saltEnc[64];
if (ext->hmac_secret_present == EXT_HMAC_SECRET_PARSED)
{
printf1(TAG_CTAP, "Processing hmac-secret..\r\n");
memmove(saltEnc, ext->hmac_secret.saltEnc, sizeof(saltEnc));
crypto_ecc256_shared_secret((uint8_t*) &ext->hmac_secret.keyAgreement.pubkey,
KEY_AGREEMENT_PRIV,
shared_secret);
crypto_sha256_init();
crypto_sha256_update(shared_secret, 32);
crypto_sha256_final(shared_secret);
crypto_sha256_hmac_init(shared_secret, 32, hmac);
crypto_sha256_update(saltEnc, ext->hmac_secret.saltLen);
crypto_sha256_hmac_final(shared_secret, 32, hmac);
if (memcmp(ext->hmac_secret.saltAuth, hmac, 16) == 0)
{
printf1(TAG_CTAP, "saltAuth is valid\r\n");
}
else
{
printf1(TAG_CTAP, "saltAuth is invalid\r\n");
return CTAP2_ERR_EXTENSION_FIRST;
}
// Generate credRandom
crypto_sha256_hmac_init(CRYPTO_TRANSPORT_KEY2, 0, credRandom);
crypto_sha256_update((uint8_t*)&ext->hmac_secret.credential->id, sizeof(CredentialId));
crypto_sha256_update(&getAssertionState.user_verified, 1);
crypto_sha256_hmac_final(CRYPTO_TRANSPORT_KEY2, 0, credRandom);
// Decrypt saltEnc
crypto_aes256_init(shared_secret, NULL);
crypto_aes256_decrypt(saltEnc, ext->hmac_secret.saltLen);
// Generate outputs
crypto_sha256_hmac_init(credRandom, 32, hmac_secret_output);
crypto_sha256_update(saltEnc, 32);
crypto_sha256_hmac_final(credRandom, 32, hmac_secret_output);
if (ext->hmac_secret.saltLen == 64)
{
crypto_sha256_hmac_init(credRandom, 32, hmac_secret_output + 32);
crypto_sha256_update(saltEnc + 32, 32);
crypto_sha256_hmac_final(credRandom, 32, hmac_secret_output + 32);
}
// Encrypt for final output
crypto_aes256_init(shared_secret, NULL);
crypto_aes256_encrypt(hmac_secret_output, ext->hmac_secret.saltLen);
extensions_used += 1;
hmac_secret_output_is_valid = 1;
}
else if (ext->hmac_secret_present == EXT_HMAC_SECRET_REQUESTED)
{
extensions_used += 1;
hmac_secret_requested_is_valid = 1;
}
if (ext->cred_protect != EXT_CRED_PROTECT_INVALID) {
if (
ext->cred_protect == EXT_CRED_PROTECT_OPTIONAL ||
ext->cred_protect == EXT_CRED_PROTECT_OPTIONAL_WITH_CREDID ||
ext->cred_protect == EXT_CRED_PROTECT_REQUIRED
)
{
extensions_used += 1;
cred_protect_is_valid = 1;
}
}
if (extensions_used > 0)
{
// output
cbor_encoder_init(&extensions, ext_encoder_buf, *ext_encoder_buf_size, 0);
{
CborEncoder extension_output_map;
ret = cbor_encoder_create_map(&extensions, &extension_output_map, extensions_used);
check_ret(ret);
if (hmac_secret_output_is_valid) {
{
ret = cbor_encode_text_stringz(&extension_output_map, "hmac-secret");
check_ret(ret);
ret = cbor_encode_byte_string(&extension_output_map, hmac_secret_output, ext->hmac_secret.saltLen);
check_ret(ret);
}
}
if (cred_protect_is_valid) {
{
ret = cbor_encode_text_stringz(&extension_output_map, "credProtect");
check_ret(ret);
ret = cbor_encode_int(&extension_output_map, ext->cred_protect);
check_ret(ret);
}
}
if (hmac_secret_requested_is_valid) {
{
ret = cbor_encode_text_stringz(&extension_output_map, "hmac-secret");
check_ret(ret);
ret = cbor_encode_boolean(&extension_output_map, 1);
check_ret(ret);
}
}
ret = cbor_encoder_close_container(&extensions, &extension_output_map);
check_ret(ret);
}
*ext_encoder_buf_size = cbor_encoder_get_buffer_size(&extensions, ext_encoder_buf);
} else
{
*ext_encoder_buf_size = 0;
}
return 0;
}
static unsigned int get_credential_id_size(int type)
{
if (type == PUB_KEY_CRED_CTAP1)
return U2F_KEY_HANDLE_SIZE;
if (type == PUB_KEY_CRED_CUSTOM)
return getAssertionState.customCredIdSize;
return sizeof(CredentialId);
}
static int ctap2_user_presence_test()
{
device_set_status(CTAPHID_STATUS_UPNEEDED);
int ret = ctap_user_presence_test(CTAP2_UP_DELAY_MS);
if ( ret > 1 )
{
return CTAP2_ERR_PROCESSING;
}
else if ( ret > 0 )
{
return CTAP1_ERR_SUCCESS;
}
else if (ret < 0)
{
return CTAP2_ERR_KEEPALIVE_CANCEL;
}
else
{
return CTAP2_ERR_ACTION_TIMEOUT;
}
}
static int ctap_make_auth_data(struct rpId * rp, CborEncoder * map, uint8_t * auth_data_buf, uint32_t * len, CTAP_credInfo * credInfo, CTAP_extensions * extensions)
{
CborEncoder cose_key;
unsigned int auth_data_sz = sizeof(CTAP_authDataHeader);
uint32_t count;
CTAP_residentKey rk, rk2;
CTAP_authData * authData = (CTAP_authData *)auth_data_buf;
uint8_t * cose_key_buf = auth_data_buf + sizeof(CTAP_authData);
// memset(&cose_key, 0, sizeof(CTAP_residentKey));
memset(&rk, 0, sizeof(CTAP_residentKey));
memset(&rk2, 0, sizeof(CTAP_residentKey));
if((sizeof(CTAP_authDataHeader)) > *len)
{
printf1(TAG_ERR,"assertion fail, auth_data_buf must be at least %d bytes\n", sizeof(CTAP_authData) - sizeof(CTAP_attestHeader));
exit(1);
}
crypto_sha256_init();
crypto_sha256_update(rp->id, rp->size);
crypto_sha256_final(authData->head.rpIdHash);
count = auth_data_update_count(&authData->head);
int but;
but = ctap2_user_presence_test();
if (CTAP2_ERR_PROCESSING == but)
{
authData->head.flags = (0 << 0); // User presence disabled
}
else
{
check_retr(but);
authData->head.flags = (1 << 0); // User presence
}
device_set_status(CTAPHID_STATUS_PROCESSING);
authData->head.flags |= (ctap_is_pin_set() << 2);
if (credInfo != NULL)
{
// add attestedCredentialData
authData->head.flags |= (1 << 6);//include attestation data
cbor_encoder_init(&cose_key, cose_key_buf, *len - sizeof(CTAP_authData), 0);
device_read_aaguid(authData->attest.aaguid);
authData->attest.credLenL = sizeof(CredentialId) & 0x00FF;
authData->attest.credLenH = (sizeof(CredentialId) & 0xFF00) >> 8;
memset((uint8_t*)&authData->attest.id, 0, sizeof(CredentialId));
ctap_generate_rng(authData->attest.id.entropy.nonce, CREDENTIAL_NONCE_SIZE);
uint8_t alg = credInfo->COSEAlgorithmIdentifier == COSE_ALG_EDDSA? CREDID_ALG_EDDSA : CREDID_ALG_ES256;
add_masked_metadata_for_credential(&authData->attest.id, extensions->cred_protect | (alg << 16));
authData->attest.id.count = count;
memmove(authData->attest.id.rpIdHash, authData->head.rpIdHash, 32);
// Make a tag we can later check to make sure this is a token we made
make_auth_tag(authData->head.rpIdHash, authData->attest.id.entropy.nonce, count, authData->attest.id.tag);
// resident key
if (credInfo->rk)
{
memmove(&rk.id, &authData->attest.id, sizeof(CredentialId));
memmove(&rk.user, &credInfo->user, sizeof(CTAP_userEntity));
// Copy rpId to RK, but it could be cropped.
int rp_id_size = rp->size < sizeof(rk.rpId) ? rp->size : sizeof(rk.rpId);
memmove(rk.rpId, rp->id, rp_id_size);
rk.rpIdSize = rp_id_size;
unsigned int index = STATE.rk_stored;
unsigned int i;
for (i = 0; i < index; i++)
{
int raw_i = load_nth_valid_rk(i, &rk2);
if (is_matching_rk(&rk, &rk2))
{
ctap_overwrite_rk(raw_i, &rk);
goto done_rk;
}
}
for (i = 0; i < ctap_rk_size(); i++){
ctap_load_rk(i, &rk2);
if ( ! ctap_rk_is_valid(&rk2) ){
ctap_increment_rk_store();
ctap_store_rk(i, &rk);
printf1(TAG_GREEN, "Created rk %d:", i); dump_hex1(TAG_GREEN, rk.id.rpIdHash, 32);
goto done_rk;
}
}
printf2(TAG_ERR, "Out of memory for resident keys\r\n");
return CTAP2_ERR_KEY_STORE_FULL;
}
done_rk:
printf1(TAG_GREEN, "MADE credId: "); dump_hex1(TAG_GREEN, (uint8_t*) &authData->attest.id, sizeof(CredentialId));
ctap_generate_cose_key(&cose_key, (uint8_t*)&authData->attest.id, sizeof(CredentialId), credInfo->publicKeyCredentialType, credInfo->COSEAlgorithmIdentifier);
auth_data_sz = sizeof(CTAP_authData) + cbor_encoder_get_buffer_size(&cose_key, cose_key_buf);
}
*len = auth_data_sz;
return 0;
}
/**
*
* @param in_sigbuf IN location to deposit signature (must be 64 bytes)
* @param out_sigder OUT location to deposit der signature (must be 72 bytes)
* @return length of der signature
* // FIXME add tests for maximum and minimum length of the input and output
*/
int ctap_encode_der_sig(const uint8_t * const in_sigbuf, uint8_t * const out_sigder)
{
// Need to caress into dumb der format ..
uint8_t i;
uint8_t lead_s = 0; // leading zeros
uint8_t lead_r = 0;
for (i=0; i < 32; i++)
{
if (in_sigbuf[i] == 0)
{
lead_r++;
}
else
{
break;
}
}
for (i=0; i < 32; i++)
{
if (in_sigbuf[i+32] == 0)
{
lead_s++;
}
else
{
break;
}
}
int8_t pad_s = ((in_sigbuf[32 + lead_s] & 0x80) == 0x80);
int8_t pad_r = ((in_sigbuf[0 + lead_r] & 0x80) == 0x80);
memset(out_sigder, 0, 72);
out_sigder[0] = 0x30;
out_sigder[1] = 0x44 + pad_s + pad_r - lead_s - lead_r;
// R ingredient
out_sigder[2] = 0x02;
out_sigder[3 + pad_r] = 0;
out_sigder[3] = 0x20 + pad_r - lead_r;
memmove(out_sigder + 4 + pad_r, in_sigbuf + lead_r, 32u - lead_r);
// S ingredient
out_sigder[4 + 32 + pad_r - lead_r] = 0x02;
out_sigder[5 + 32 + pad_r + pad_s - lead_r] = 0;
out_sigder[5 + 32 + pad_r - lead_r] = 0x20 + pad_s - lead_s;
memmove(out_sigder + 6 + 32 + pad_r + pad_s - lead_r, in_sigbuf + 32u + lead_s, 32u - lead_s);
return 0x46 + pad_s + pad_r - lead_r - lead_s;
}
// require load_key prior to this
// @data data to hash before signature, MUST have room to append clientDataHash for ED25519
// @clientDataHash for signature
// @tmp buffer for hash. (can be same as data if data >= 32 bytes)
// @sigbuf OUT location to deposit signature (must be 64 bytes)
// @sigder OUT location to deposit der signature (must be 72 bytes)
// @return length of der signature
int ctap_calculate_signature(uint8_t * data, int datalen, uint8_t * clientDataHash, uint8_t * hashbuf, uint8_t * sigbuf, uint8_t * sigder, int32_t alg)
{
// calculate attestation sig
if (alg == COSE_ALG_EDDSA)
{
crypto_ed25519_sign(data, datalen, clientDataHash, CLIENT_DATA_HASH_SIZE, sigder); // not DER, just plain binary!
return 64;
}
else
{
crypto_sha256_init();
crypto_sha256_update(data, datalen);
crypto_sha256_update(clientDataHash, CLIENT_DATA_HASH_SIZE);
crypto_sha256_final(hashbuf);
crypto_ecc256_sign(hashbuf, 32, sigbuf);
return ctap_encode_der_sig(sigbuf,sigder);
}
}
uint8_t ctap_add_attest_statement(CborEncoder * map, uint8_t * sigder, int len)
{
int ret;
uint8_t cert[1024];
uint16_t cert_size = device_attestation_cert_der_get_size();
if (cert_size > sizeof(cert)){
printf2(TAG_ERR,"Certificate is too large for CTAP2 buffer\r\n");
return CTAP2_ERR_PROCESSING;
}
device_attestation_read_cert_der(cert);
CborEncoder stmtmap;
CborEncoder x5carr;
ret = cbor_encode_int(map,RESP_attStmt);
check_ret(ret);
ret = cbor_encoder_create_map(map, &stmtmap, 3);
check_ret(ret);
{
ret = cbor_encode_text_stringz(&stmtmap,"alg");
check_ret(ret);
ret = cbor_encode_int(&stmtmap,COSE_ALG_ES256);
check_ret(ret);
}
{
ret = cbor_encode_text_stringz(&stmtmap,"sig");
check_ret(ret);
ret = cbor_encode_byte_string(&stmtmap, sigder, len);
check_ret(ret);
}
{
ret = cbor_encode_text_stringz(&stmtmap,"x5c");
check_ret(ret);
ret = cbor_encoder_create_array(&stmtmap, &x5carr, 1);
check_ret(ret);
{
ret = cbor_encode_byte_string(&x5carr, cert, device_attestation_cert_der_get_size());
check_ret(ret);
ret = cbor_encoder_close_container(&stmtmap, &x5carr);
check_ret(ret);
}
}
ret = cbor_encoder_close_container(map, &stmtmap);
check_ret(ret);
return 0;
}
// Return 1 if credential belongs to this token
int ctap_authenticate_credential(struct rpId * rp, CTAP_credentialDescriptor * desc)
{
uint8_t rpIdHash[32];
uint8_t tag[16];
switch(desc->type)
{
case PUB_KEY_CRED_PUB_KEY:
crypto_sha256_init();
crypto_sha256_update(rp->id, rp->size);
crypto_sha256_final(rpIdHash);
printf1(TAG_RED,"rpId: %s\r\n", rp->id); dump_hex1(TAG_RED,rp->id, rp->size);
if (memcmp(desc->credential.id.rpIdHash, rpIdHash, 32) != 0)
{
return 0;
}
make_auth_tag(rpIdHash, desc->credential.id.entropy.nonce, desc->credential.id.count, tag);
return (memcmp(desc->credential.id.tag, tag, CREDENTIAL_TAG_SIZE) == 0);
break;
case PUB_KEY_CRED_CTAP1:
crypto_sha256_init();
crypto_sha256_update(rp->id, rp->size);
crypto_sha256_final(rpIdHash);
return u2f_authenticate_credential((struct u2f_key_handle *)&desc->credential.id, U2F_KEY_HANDLE_SIZE,rpIdHash);
break;
case PUB_KEY_CRED_CUSTOM:
return is_extension_request(getAssertionState.customCredId, getAssertionState.customCredIdSize);
break;
default:
printf1(TAG_ERR, "PUB_KEY_CRED_UNKNOWN %x\r\n",desc->type);
break;
}
return 0;
}
uint8_t ctap_make_credential(CborEncoder * encoder, uint8_t * request, int length)
{
CTAP_makeCredential MC;
int ret;
unsigned int i;
uint8_t auth_data_buf[310];
CTAP_credentialDescriptor * excl_cred = (CTAP_credentialDescriptor *) auth_data_buf;
uint8_t * sigbuf = auth_data_buf + 32;
uint8_t * sigder = auth_data_buf + 32 + 64;
ret = ctap_parse_make_credential(&MC,encoder,request,length);
if (ret != 0)
{
printf2(TAG_ERR,"error, parse_make_credential failed\n");
return ret;
}
if (MC.pinAuthEmpty)
{
ret = ctap2_user_presence_test();
check_retr(ret);
return ctap_is_pin_set() == 1 ? CTAP2_ERR_PIN_AUTH_INVALID : CTAP2_ERR_PIN_NOT_SET;
}
if ((MC.paramsParsed & MC_requiredMask) != MC_requiredMask)
{
printf2(TAG_ERR,"error, required parameter(s) for makeCredential are missing\n");
return CTAP2_ERR_MISSING_PARAMETER;
}
if (ctap_is_pin_set() == 1 && MC.pinAuthPresent == 0)
{
printf2(TAG_ERR,"pinAuth is required\n");
return CTAP2_ERR_PIN_REQUIRED;
}
else
{
if (ctap_is_pin_set() || (MC.pinAuthPresent))
{
ret = verify_pin_auth(MC.pinAuth, MC.clientDataHash);
check_retr(ret);
}
}
if (MC.up == 1 || MC.up == 0)
{
return CTAP2_ERR_INVALID_OPTION;
}
// crypto_aes256_init(CRYPTO_TRANSPORT_KEY, NULL);
for (i = 0; i < MC.excludeListSize; i++)
{
ret = parse_credential_descriptor(&MC.excludeList, excl_cred);
if (ret == CTAP2_ERR_CBOR_UNEXPECTED_TYPE)
{
continue;
}
check_retr(ret);
printf1(TAG_GREEN, "checking credId: "); dump_hex1(TAG_GREEN, (uint8_t*) &excl_cred->credential.id, sizeof(CredentialId));
if (ctap_authenticate_credential(&MC.rp, excl_cred))
{
if ( check_credential_metadata(&excl_cred->credential.id, MC.pinAuthPresent, 1) == 0)
{
ret = ctap2_user_presence_test();
check_retr(ret);
printf1(TAG_MC, "Cred %d failed!\r\n",i);
return CTAP2_ERR_CREDENTIAL_EXCLUDED;
}
}
ret = cbor_value_advance(&MC.excludeList);
check_ret(ret);
}
CborEncoder map;
ret = cbor_encoder_create_map(encoder, &map, 3);
check_ret(ret);