/
yubihsm.c
5011 lines (4065 loc) · 140 KB
/
yubihsm.c
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/*
* Copyright 2015-2018 Yubico AB
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "yubihsm.h"
#include "internal.h"
#ifdef __WIN32
#include <winsock.h>
#else
#include <arpa/inet.h>
#include <dlfcn.h>
#include <strings.h>
#endif
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include "../common/rand.h"
#include "../common/pkcs5.h"
#include "../common/hash.h"
#include "../common/ecdh.h"
#include "../aes_cmac/aes_cmac.h"
#include "debug_lib.h"
#include "../common/insecure_memzero.h"
#include "../ykhsmauth/ykhsmauth.h"
#define STATIC_USB_BACKEND "usb"
#define STATIC_HTTP_BACKEND "http"
// If any of the values in scp.h are changed
// they should be mirrored in yubihsm.h
#ifdef _MSVC
_STATIC_ASSERT(SCP_HOST_CHAL_LEN == YH_HOST_CHAL_LEN);
_STATIC_ASSERT(SCP_CONTEXT_LEN == YH_CONTEXT_LEN);
_STATIC_ASSERT(SCP_MSG_BUF_SIZE == YH_MSG_BUF_SIZE);
_STATIC_ASSERT(SCP_KEY_LEN == YH_KEY_LEN);
#define strtok_r strtok_s
#define strcasecmp _stricmp
#else
_Static_assert(SCP_HOST_CHAL_LEN == YH_HOST_CHAL_LEN,
"Host challenge length mismatch");
_Static_assert(SCP_CONTEXT_LEN == YH_CONTEXT_LEN, "Context length mismatch");
_Static_assert(SCP_MSG_BUF_SIZE == YH_MSG_BUF_SIZE,
"Message buffer size mismatch");
_Static_assert(SCP_KEY_LEN == YH_KEY_LEN, "Message buffer size mismatch");
#endif
#define LIST_SEPARATORS ":,;|"
uint8_t _yh_verbosity YH_INTERNAL = 0;
FILE *_yh_output YH_INTERNAL = NULL;
static yh_rc compute_full_mac_ex(const uint8_t *data, uint16_t data_len,
aes_context *aes_ctx, uint8_t *mac) {
aes_cmac_context_t ctx = {0};
if (aes_cmac_init(aes_ctx, &ctx)) {
DBG_ERR("aes_cmac_init failed");
return YHR_GENERIC_ERROR;
}
if (aes_cmac_encrypt(&ctx, data, data_len, mac)) {
DBG_ERR("aes_cmac_encrypt failed");
aes_cmac_destroy(&ctx);
return YHR_GENERIC_ERROR;
}
aes_cmac_destroy(&ctx);
return YHR_SUCCESS;
}
static yh_rc compute_full_mac(const uint8_t *data, uint16_t data_len,
const uint8_t *key, uint16_t key_len,
uint8_t *mac) {
aes_context aes_ctx = {0};
if (aes_set_key(key, key_len, &aes_ctx)) {
DBG_ERR("aes_set_key failed");
return YHR_GENERIC_ERROR;
}
yh_rc yrc = compute_full_mac_ex(data, data_len, &aes_ctx, mac);
aes_destroy(&aes_ctx);
return yrc;
}
static yh_rc compute_cryptogram_ex(aes_context *aes_ctx, uint8_t type,
const uint8_t context[SCP_CONTEXT_LEN],
uint16_t L, uint8_t *key_out) {
uint8_t n_iterations = 0;
uint8_t input[16 + SCP_CONTEXT_LEN] = {0};
uint8_t *ptr = input;
if (L == 0x40 || L == 0x80)
n_iterations = 1;
else if (L == 0xc0 || L == 0x100)
n_iterations = 2;
else
return YHR_INVALID_PARAMETERS;
// Label
memset(ptr, 0, 11);
ptr += 11;
*ptr++ = type;
// Delimiter byte
*ptr++ = 0;
// L
*ptr++ = (L & 0xff00) >> 8;
*ptr++ = (L & 0x00ff);
// i
*ptr++ = 0x01;
// Context
memcpy(ptr, context, SCP_CONTEXT_LEN);
ptr += SCP_CONTEXT_LEN;
aes_cmac_context_t ctx = {0};
if (aes_cmac_init(aes_ctx, &ctx)) {
DBG_ERR("aes_cmac_init failed");
return YHR_GENERIC_ERROR;
}
uint8_t result[2 * SCP_PRF_LEN] = {0};
for (uint8_t i = 0; i < n_iterations; i++) {
if (aes_cmac_encrypt(&ctx, input, ptr - input,
result + (i * SCP_PRF_LEN))) {
DBG_ERR("aes_cmac_encrypt failed");
aes_cmac_destroy(&ctx);
return YHR_GENERIC_ERROR;
}
// Update i
input[15]++;
}
memcpy(key_out, result, L / 8);
aes_cmac_destroy(&ctx);
return YHR_SUCCESS;
}
static yh_rc compute_cryptogram(const uint8_t *key, uint16_t key_len,
uint8_t type,
const uint8_t context[SCP_CONTEXT_LEN],
uint16_t L, uint8_t *key_out) {
aes_context aes_ctx = {0};
if (aes_set_key(key, key_len, &aes_ctx)) {
DBG_ERR("aes_set_key failed");
return YHR_GENERIC_ERROR;
}
yh_rc yrc = compute_cryptogram_ex(&aes_ctx, type, context, L, key_out);
aes_destroy(&aes_ctx);
return yrc;
}
static void increment_ctr(uint8_t *ctr, uint16_t len) {
while (len > 0) {
if (++ctr[--len]) {
break;
}
}
}
static yh_rc translate_device_error(uint8_t device_error) {
enum {
_DEVICE_OK = 0x00, // No error
_DEVICE_INVALID_COMMAND = 0x01, // Invalid command
_DEVICE_INVALID_DATA = 0x02, // Malformed command / invalid data
_DEVICE_INVALID_SESSION = 0x03, // Invalid session
_DEVICE_AUTHENTICATION_FAILED =
0x04, // Message encryption / verification failed
_DEVICE_SESSIONS_FULL = 0x05, // All sessions are allocated
_DEVICE_SESSION_FAILED = 0x06, // Session creation failed
_DEVICE_STORAGE_FAILED = 0x07, // Storage failure
_DEVICE_WRONG_LENGTH = 0x08, // Wrong length
_DEVICE_INSUFFICIENT_PERMISSIONS = 0x09, // Wrong permissions for operation
_DEVICE_LOG_FULL = 0x0a, // Log buffer is full and forced audit is set
_DEVICE_OBJECT_NOT_FOUND = 0x0b, // Object not found
_DEVICE_INVALID_ID = 0x0c, // Invalid ID
_DEVICE_SSH_CA_CONSTRAINT_VIOLIATION = 0x0e, // CA constraint violation
_DEVICE_INVALID_OTP = 0x0f, // Invalid OTP
_DEVICE_DEMO_MODE = 0x10, // Demo mode, power cycle device
_DEVICE_OBJECT_EXISTS = 0x11, // Object with that ID already exists
_DEVICE_ALGORITHM_DISABLED = 0x12, // Algorithm is disabled
_DEVICE_COMMAND_UNEXECUTED =
0xff, // The command execution has not terminated
};
switch (device_error) {
case _DEVICE_OK:
return YHR_DEVICE_OK;
case _DEVICE_INVALID_COMMAND:
return YHR_DEVICE_INVALID_COMMAND;
case _DEVICE_INVALID_DATA:
return YHR_DEVICE_INVALID_DATA;
case _DEVICE_INVALID_SESSION:
return YHR_DEVICE_INVALID_SESSION;
case _DEVICE_AUTHENTICATION_FAILED:
return YHR_DEVICE_AUTHENTICATION_FAILED;
case _DEVICE_SESSIONS_FULL:
return YHR_DEVICE_SESSIONS_FULL;
case _DEVICE_SESSION_FAILED:
return YHR_DEVICE_SESSION_FAILED;
case _DEVICE_STORAGE_FAILED:
return YHR_DEVICE_STORAGE_FAILED;
case _DEVICE_WRONG_LENGTH:
return YHR_DEVICE_WRONG_LENGTH;
case _DEVICE_INSUFFICIENT_PERMISSIONS:
return YHR_DEVICE_INSUFFICIENT_PERMISSIONS;
case _DEVICE_LOG_FULL:
return YHR_DEVICE_LOG_FULL;
case _DEVICE_OBJECT_NOT_FOUND:
return YHR_DEVICE_OBJECT_NOT_FOUND;
case _DEVICE_INVALID_ID:
return YHR_DEVICE_INVALID_ID;
case _DEVICE_SSH_CA_CONSTRAINT_VIOLIATION:
return YHR_DEVICE_SSH_CA_CONSTRAINT_VIOLATION;
case _DEVICE_INVALID_OTP:
return YHR_DEVICE_INVALID_OTP;
case _DEVICE_DEMO_MODE:
return YHR_DEVICE_DEMO_MODE;
case _DEVICE_OBJECT_EXISTS:
return YHR_DEVICE_OBJECT_EXISTS;
case _DEVICE_ALGORITHM_DISABLED:
return YHR_DEVICE_ALGORITHM_DISABLED;
case _DEVICE_COMMAND_UNEXECUTED:
return YHR_DEVICE_COMMAND_UNEXECUTED;
}
return YHR_GENERIC_ERROR;
}
static yh_rc send_msg(yh_connector *connector, Msg *msg, Msg *response,
const char *identifier) {
if (connector == NULL || connector->bf == NULL) {
DBG_ERR("No backend loaded");
return YHR_INVALID_PARAMETERS;
}
DBG_NET(msg, dump_msg);
yh_rc yrc = connector->bf->backend_send_msg(connector->connection, msg,
response, identifier);
if (yrc == YHR_SUCCESS) {
if (ntohs(response->st.len) > sizeof(response->st.data)) {
return YHR_WRONG_LENGTH;
}
DBG_NET(response, dump_response);
}
return yrc;
}
yh_rc yh_send_plain_msg(yh_connector *connector, yh_cmd cmd,
const uint8_t *data, size_t data_len,
yh_cmd *response_cmd, uint8_t *response,
size_t *response_len) {
if (connector == NULL || (data_len != 0 && data == NULL) ||
response_cmd == NULL || response == NULL || response_len == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
Msg msg = {0};
Msg response_msg = {0};
if (data_len > sizeof(msg.st.data)) {
DBG_ERR("Tried to transfer oversized data (%zu > %zu)", data_len,
sizeof(msg.st.data));
return YHR_INVALID_PARAMETERS;
}
msg.st.cmd = cmd;
msg.st.len = htons(data_len);
if (data_len > 0) {
memcpy(msg.st.data, data, data_len);
}
yh_rc yrc = send_msg(connector, &msg, &response_msg, NULL);
if (yrc != YHR_SUCCESS) {
DBG_ERR("send_msg %s", yh_strerror(yrc));
return yrc;
}
uint16_t len = ntohs(response_msg.st.len);
*response_cmd = response_msg.st.cmd;
if (*response_len < len) {
DBG_ERR("%s (received %u Bytes, can fit %zu Bytes) ",
yh_strerror(YHR_BUFFER_TOO_SMALL), len, *response_len);
*response_len = len;
return YHR_BUFFER_TOO_SMALL;
}
*response_len = len;
memcpy(response, response_msg.st.data, len);
return (*response_cmd == YHC_ERROR) ? translate_device_error(response[0])
: YHR_SUCCESS;
}
static yh_rc send_authenticated_msg(Scp_ctx *session, Msg *msg, Msg *resp,
bool require_resp) {
DBG_NET(msg, dump_msg);
uint16_t len = ntohs(msg->st.len);
uint16_t raw_len = len + 3;
msg->st.len = htons(len + SCP_MAC_LEN);
uint8_t mac_buf[SCP_PRF_LEN + sizeof(Msg)] = {0};
memcpy(mac_buf, session->mac_chaining_value, SCP_PRF_LEN);
memcpy(mac_buf + SCP_PRF_LEN, msg->raw, raw_len);
yh_rc yrc = compute_full_mac(mac_buf, SCP_PRF_LEN + raw_len, session->s_mac,
SCP_KEY_LEN, session->mac_chaining_value);
if (yrc != YHR_SUCCESS) {
DBG_ERR("compute_full_mac %s", yh_strerror(yrc));
return yrc;
}
memcpy(msg->st.data + len, session->mac_chaining_value, SCP_MAC_LEN);
yrc = send_msg(session->parent, msg, resp, session->identifier);
if (yrc != YHR_SUCCESS) {
DBG_ERR("send_msg %s", yh_strerror(yrc));
return yrc;
}
len = ntohs(resp->st.len);
if (len >= SCP_MAC_LEN) {
raw_len = 3 + len - SCP_MAC_LEN;
memcpy(mac_buf, session->mac_chaining_value, SCP_PRF_LEN);
memcpy(mac_buf + SCP_PRF_LEN, resp->raw, raw_len);
uint8_t host_mac[SCP_PRF_LEN] = {0};
yrc = compute_full_mac(mac_buf, SCP_PRF_LEN + raw_len, session->s_rmac,
SCP_KEY_LEN, host_mac);
if (yrc != YHR_SUCCESS) {
DBG_ERR("compute_full_mac %s", yh_strerror(yrc));
return yrc;
}
len -= SCP_MAC_LEN;
resp->st.len = htons(len);
if (memcmp(host_mac, resp->st.data + len, SCP_MAC_LEN)) {
DBG_ERR("Bad MAC received");
yrc = YHR_MAC_MISMATCH;
}
} else if (require_resp) {
if (len != 1 || resp->st.cmd != YHC_ERROR) {
DBG_ERR("No MAC received");
yrc = YHR_MAC_MISMATCH;
}
}
DBG_NET(resp, dump_response);
return yrc;
}
static yh_rc send_encrypted_msg(Scp_ctx *session, yh_cmd cmd,
const uint8_t *data, size_t data_len,
yh_cmd *response_cmd, uint8_t *response,
size_t *response_len) {
if (session == NULL || (data_len != 0 && data == NULL) ||
data_len > SCP_MSG_BUF_SIZE || response_cmd == NULL || response == NULL ||
response_len == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
// Payload { cmd | cmd_len | data }
uint16_t len = 3 + data_len;
// Padded payload { cmd | cmd_len | data | padding 1-16 bytes }
if (aes_add_padding(NULL, 0, &len)) {
return YHR_INVALID_PARAMETERS;
}
// Outer command { cmd | cmd_len | sid | encrypted payload | mac }
if (3 + 1 + len + SCP_MAC_LEN > SCP_MSG_BUF_SIZE) {
DBG_ERR("%s: %u", yh_strerror(YHR_BUFFER_TOO_SMALL), 3 + 1 + len + SCP_MAC_LEN);
return YHR_BUFFER_TOO_SMALL;
}
Msg msg = {0}, enc_msg = {0};
msg.st.cmd = cmd;
msg.st.len = htons(data_len);
if (data_len > 0) {
memcpy(msg.st.data, data, data_len);
}
DBG_NET(&msg, dump_msg);
len = 3 + data_len;
if (aes_add_padding(msg.raw, sizeof(msg.raw), &len)) {
return YHR_INVALID_PARAMETERS;
}
aes_context aes_ctx = {0};
if (aes_set_key(session->s_enc, SCP_KEY_LEN, &aes_ctx)) {
DBG_ERR("aes_set_key %s", yh_strerror(YHR_GENERIC_ERROR));
return YHR_GENERIC_ERROR;
}
yh_rc yrc = YHR_SUCCESS;
uint8_t encrypted_ctr[AES_BLOCK_SIZE];
if (aes_encrypt(session->ctr, encrypted_ctr, &aes_ctx)) {
DBG_ERR("aes_encrypt %s", yh_strerror(YHR_GENERIC_ERROR));
yrc = YHR_GENERIC_ERROR;
goto cleanup;
}
enc_msg.st.cmd = YHC_SESSION_MESSAGE;
enc_msg.st.len = htons(len + 1);
enc_msg.st.data[0] = session->sid;
if (aes_cbc_encrypt(msg.raw, enc_msg.st.data + 1, len, encrypted_ctr,
&aes_ctx)) {
DBG_ERR("aes_cbc_encrypt %s", yh_strerror(YHR_GENERIC_ERROR));
yrc = YHR_GENERIC_ERROR;
goto cleanup;
}
yrc = send_authenticated_msg(session, &enc_msg, &msg, true);
if (yrc != YHR_SUCCESS) {
DBG_ERR("send_authenticated_msg %s", yh_strerror(yrc));
goto cleanup;
}
if (msg.st.cmd == YHC_ERROR) {
yrc = translate_device_error(msg.st.data[0]);
DBG_ERR("%s", yh_strerror(yrc));
*response_cmd = YHC_ERROR;
response[0] = msg.st.data[0];
*response_len = 1;
goto cleanup;
}
if (session->sid != msg.st.data[0]) {
DBG_ERR("Session ID mismatch, expected %d, got %d", session->sid,
msg.st.data[0]);
yrc = YHR_DEVICE_INVALID_SESSION;
goto cleanup;
}
len = ntohs(msg.st.len);
// The minimum message is { sid | 1 aes block }
if (len < 1 + AES_BLOCK_SIZE) {
DBG_ERR("%s", yh_strerror(YHR_BUFFER_TOO_SMALL));
yrc = YHR_BUFFER_TOO_SMALL;
goto cleanup;
}
len -= 1;
if (aes_cbc_decrypt(msg.st.data + 1, enc_msg.raw, len, encrypted_ctr,
&aes_ctx)) {
DBG_ERR("aes_cbc_decrypt %s", yh_strerror(YHR_GENERIC_ERROR));
yrc = YHR_GENERIC_ERROR;
goto cleanup;
}
aes_remove_padding(enc_msg.raw, &len);
if (len < 3 || len - 3 != ntohs(enc_msg.st.len)) {
DBG_ERR("aes_remove_padding %s", yh_strerror(YHR_WRONG_LENGTH));
yrc = YHR_WRONG_LENGTH;
goto cleanup;
}
increment_ctr(session->ctr, SCP_PRF_LEN);
DBG_NET(&enc_msg, dump_response);
*response_cmd = enc_msg.st.cmd;
len -= 3;
if (*response_len < len) {
DBG_ERR("%s (received %u Bytes, can fit %zu Bytes) ",
yh_strerror(YHR_BUFFER_TOO_SMALL), len, *response_len);
*response_len = len;
yrc = YHR_BUFFER_TOO_SMALL;
goto cleanup;
}
memcpy(response, enc_msg.st.data, len);
*response_len = len;
if (*response_cmd == YHC_ERROR) {
yrc = translate_device_error(response[0]);
}
cleanup:
aes_destroy(&aes_ctx);
insecure_memzero(&msg, sizeof(msg));
insecure_memzero(&enc_msg, sizeof(enc_msg));
return yrc;
}
yh_rc yh_send_secure_msg(yh_session *session, yh_cmd cmd, const uint8_t *data,
size_t data_len, yh_cmd *response_cmd,
uint8_t *response, size_t *response_len) {
size_t saved_len = *response_len;
yh_rc yrc = send_encrypted_msg(&session->s, cmd, data, data_len, response_cmd,
response, response_len);
if ((yrc == YHR_DEVICE_INVALID_SESSION ||
yrc == YHR_DEVICE_AUTHENTICATION_FAILED) &&
session->authkey_id) {
DBG_INFO("Recreating session");
yrc = yh_create_session(session->s.parent, session->authkey_id,
session->key_enc, SCP_KEY_LEN, session->key_mac,
SCP_KEY_LEN, true, &session);
if (yrc != YHR_SUCCESS) {
return yrc;
}
*response_len = saved_len;
yrc = send_encrypted_msg(&session->s, cmd, data, data_len, response_cmd,
response, response_len);
}
return yrc;
}
static yh_rc derive_key(const uint8_t *password, size_t password_len,
uint8_t *key, size_t key_len) {
if (!pkcs5_pbkdf2_hmac(password, password_len,
(const uint8_t *) YH_DEFAULT_SALT,
strlen(YH_DEFAULT_SALT), YH_DEFAULT_ITERS, _SHA256,
key, key_len)) {
return YHR_GENERIC_ERROR;
}
return YHR_SUCCESS;
}
yh_rc yh_create_session_derived(yh_connector *connector, uint16_t authkey_id,
const uint8_t *password, size_t password_len,
bool recreate, yh_session **session) {
if (connector == NULL || password == NULL || session == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
uint8_t key[2 * SCP_KEY_LEN] = {0};
yh_rc yrc = derive_key(password, password_len, key, sizeof(key));
if (yrc == YHR_SUCCESS) {
yrc = yh_create_session(connector, authkey_id, key, SCP_KEY_LEN,
key + SCP_KEY_LEN, SCP_KEY_LEN, recreate, session);
insecure_memzero(key, sizeof(key));
}
return yrc;
}
yh_rc yh_create_session(yh_connector *connector, uint16_t authkey_id,
const uint8_t *key_enc, size_t key_enc_len,
const uint8_t *key_mac, size_t key_mac_len,
bool recreate, yh_session **session) {
if (connector == NULL || key_enc == NULL || key_enc_len != SCP_KEY_LEN ||
key_mac == NULL || key_mac_len != SCP_KEY_LEN || session == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
yh_session *new_session = *session;
uint8_t host_challenge[SCP_HOST_CHAL_LEN] = {0};
size_t host_challenge_len = 0;
uint8_t card_cryptogram[SCP_CARD_CRYPTO_LEN] = {0};
size_t card_cryptogram_len = sizeof(card_cryptogram);
yh_rc yrc =
yh_begin_create_session(connector, authkey_id, NULL, host_challenge,
&host_challenge_len, card_cryptogram,
&card_cryptogram_len, &new_session);
if (yrc != YHR_SUCCESS)
goto cs_failure;
// Derive session keys
yrc = compute_cryptogram(key_enc, key_enc_len, SCP_S_ENC_DERIVATION,
new_session->context, SCP_KEY_LEN * 8,
new_session->s.s_enc);
if (yrc != YHR_SUCCESS)
goto cs_failure;
yrc = compute_cryptogram(key_mac, key_mac_len, SCP_S_MAC_DERIVATION,
new_session->context, SCP_KEY_LEN * 8,
new_session->s.s_mac);
if (yrc != YHR_SUCCESS)
goto cs_failure;
yrc = compute_cryptogram(key_mac, key_mac_len, SCP_S_RMAC_DERIVATION,
new_session->context, SCP_KEY_LEN * 8,
new_session->s.s_rmac);
if (yrc != YHR_SUCCESS)
goto cs_failure;
yrc = yh_finish_create_session(new_session, new_session->s.s_enc, YH_KEY_LEN,
new_session->s.s_mac, YH_KEY_LEN,
new_session->s.s_rmac, YH_KEY_LEN,
card_cryptogram, card_cryptogram_len);
if (yrc != YHR_SUCCESS)
goto cs_failure;
if (recreate) {
new_session->authkey_id = authkey_id;
if (new_session->key_enc != key_enc)
memcpy(new_session->key_enc, key_enc, SCP_KEY_LEN);
if (new_session->key_mac != key_mac)
memcpy(new_session->key_mac, key_mac, SCP_KEY_LEN);
} else {
new_session->authkey_id = 0;
memset(new_session->key_enc, 0, SCP_KEY_LEN);
memset(new_session->key_mac, 0, SCP_KEY_LEN);
}
*session = new_session;
return YHR_SUCCESS;
cs_failure:
// Only clear and free if we didn't reuse the session
if (new_session != *session) {
insecure_memzero(new_session, sizeof(yh_session));
free(new_session);
new_session = NULL;
}
DBG_ERR("%s", yh_strerror(yrc));
return yrc;
}
yh_rc yh_create_session_ex(yh_connector *connector, uint16_t authkey_id,
const char *key_enc_name, const char *key_mac_name,
yh_session **session) {
if (connector == NULL || key_enc_name == NULL || key_mac_name == NULL ||
session == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
yh_session *new_session = *session;
uint8_t host_challenge[SCP_HOST_CHAL_LEN] = {0};
size_t host_challenge_len = 0;
uint8_t card_cryptogram[SCP_CARD_CRYPTO_LEN] = {0};
size_t card_cryptogram_len = sizeof(card_cryptogram);
aes_context enc_ctx = {0};
aes_context mac_ctx = {0};
yh_rc yrc =
yh_begin_create_session(connector, authkey_id, NULL, host_challenge,
&host_challenge_len, card_cryptogram,
&card_cryptogram_len, &new_session);
if (yrc != YHR_SUCCESS)
goto cs_failure;
// Derive session keys
if (aes_load_key(key_enc_name, &enc_ctx)) {
DBG_ERR("aes_load_key %s failed", key_enc_name);
yrc = YHR_GENERIC_ERROR;
goto cs_failure;
}
yrc =
compute_cryptogram_ex(&enc_ctx, SCP_S_ENC_DERIVATION, new_session->context,
SCP_KEY_LEN * 8, new_session->s.s_enc);
if (yrc != YHR_SUCCESS)
goto cs_failure;
if (aes_load_key(key_mac_name, &mac_ctx)) {
DBG_ERR("aes_load_key %s failed", key_mac_name);
yrc = YHR_GENERIC_ERROR;
goto cs_failure;
}
yrc =
compute_cryptogram_ex(&mac_ctx, SCP_S_MAC_DERIVATION, new_session->context,
SCP_KEY_LEN * 8, new_session->s.s_mac);
if (yrc != YHR_SUCCESS)
goto cs_failure;
yrc =
compute_cryptogram_ex(&mac_ctx, SCP_S_RMAC_DERIVATION, new_session->context,
SCP_KEY_LEN * 8, new_session->s.s_rmac);
if (yrc != YHR_SUCCESS)
goto cs_failure;
yrc = yh_finish_create_session(new_session, new_session->s.s_enc, YH_KEY_LEN,
new_session->s.s_mac, YH_KEY_LEN,
new_session->s.s_rmac, YH_KEY_LEN,
card_cryptogram, card_cryptogram_len);
if (yrc != YHR_SUCCESS)
goto cs_failure;
aes_destroy(&enc_ctx);
aes_destroy(&mac_ctx);
new_session->authkey_id = 0;
memset(new_session->key_enc, 0, SCP_KEY_LEN);
memset(new_session->key_mac, 0, SCP_KEY_LEN);
*session = new_session;
return YHR_SUCCESS;
cs_failure:
aes_destroy(&enc_ctx);
aes_destroy(&mac_ctx);
// Only clear and free if we didn't reuse the session
if (new_session != *session) {
insecure_memzero(new_session, sizeof(yh_session));
free(new_session);
new_session = NULL;
}
DBG_ERR("%s", yh_strerror(yrc));
return yrc;
}
yh_rc yh_begin_create_session_ext(yh_connector *connector, uint16_t authkey_id,
uint8_t **context, uint8_t *card_cryptogram,
size_t card_cryptogram_len,
yh_session **session) {
uint8_t host_challenge[SCP_HOST_CHAL_LEN] = {0};
size_t host_challenge_len = 0;
return yh_begin_create_session(connector, authkey_id, context, host_challenge,
&host_challenge_len, card_cryptogram,
&card_cryptogram_len, session);
}
yh_rc yh_begin_create_session(yh_connector *connector, uint16_t authkey_id,
uint8_t **context, uint8_t *host_challenge,
size_t *host_challenge_len,
uint8_t *card_cryptogram,
size_t *card_cryptogram_len,
yh_session **session) {
if (connector == NULL || host_challenge == NULL ||
host_challenge_len == NULL || card_cryptogram == NULL ||
card_cryptogram_len == NULL || session == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
if (*host_challenge_len == 0) {
if (!rand_generate(host_challenge, SCP_HOST_CHAL_LEN)) {
DBG_ERR("Failed getting randomness");
return YHR_GENERIC_ERROR;
}
*host_challenge_len = SCP_HOST_CHAL_LEN;
}
DBG_INT(host_challenge, *host_challenge_len, "Host challenge: ");
switch (*host_challenge_len) {
case SCP_HOST_CHAL_LEN:
if (*card_cryptogram_len < SCP_CARD_CRYPTO_LEN) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
*card_cryptogram_len = SCP_CARD_CRYPTO_LEN;
break;
case YH_EC_P256_PUBKEY_LEN:
if (*card_cryptogram_len < SCP_KEY_LEN) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
*card_cryptogram_len = SCP_KEY_LEN;
break;
default:
return YHR_INVALID_PARAMETERS;
}
yh_session *new_session;
if (!*session) {
new_session = calloc(1, sizeof(yh_session));
if (new_session == NULL) {
DBG_ERR("%s", yh_strerror(YHR_MEMORY_ERROR));
return YHR_MEMORY_ERROR;
}
} else {
new_session = *session;
}
// Save link back to connector
new_session->s.parent = connector;
memcpy(new_session->context, host_challenge, *host_challenge_len);
yh_rc yrc = YHR_SUCCESS;
uint8_t identifier[8] = {0};
if (!rand_generate(identifier, sizeof(identifier))) {
DBG_ERR("Failed getting randomness");
yrc = YHR_GENERIC_ERROR;
goto bcse_failure;
}
snprintf(new_session->s.identifier, 17, "%02x%02x%02x%02x%02x%02x%02x%02x",
identifier[0], identifier[1], identifier[2], identifier[3],
identifier[4], identifier[5], identifier[6], identifier[7]);
Msg msg = {0};
Msg response_msg = {0};
// Send CREATE SESSION command
msg.st.cmd = YHC_CREATE_SESSION;
msg.st.len = htons(SCP_AUTHKEY_ID_LEN + *host_challenge_len);
uint16_t authkey_id_n = htons(authkey_id);
memcpy(msg.st.data, &authkey_id_n, SCP_AUTHKEY_ID_LEN);
memcpy(msg.st.data + SCP_AUTHKEY_ID_LEN, host_challenge, *host_challenge_len);
yrc = send_msg(connector, &msg, &response_msg, new_session->s.identifier);
if (yrc != YHR_SUCCESS) {
DBG_ERR("send_msg %s", yh_strerror(yrc));
goto bcse_failure;
}
// Parse response
if (response_msg.st.cmd != YHC_CREATE_SESSION_R) {
yrc = translate_device_error(response_msg.st.data[0]);
DBG_ERR("Device error %s (%d)", yh_strerror(yrc), response_msg.st.data[0]);
goto bcse_failure;
}
if (ntohs(response_msg.st.len) !=
1 + *host_challenge_len + *card_cryptogram_len) {
yrc = YHR_WRONG_LENGTH;
goto bcse_failure;
}
uint8_t *ptr = response_msg.st.data;
// Save sid
new_session->s.sid = (*ptr++);
DBG_INFO("Received Session ID: %d", new_session->s.sid);
// Save card challenge
memcpy(new_session->context + *host_challenge_len, ptr, *host_challenge_len);
ptr += *host_challenge_len;
DBG_INT(new_session->context + *host_challenge_len, *host_challenge_len,
"Card challenge: ");
memcpy(card_cryptogram, ptr, *card_cryptogram_len);
ptr += *card_cryptogram_len;
DBG_INT(card_cryptogram, *card_cryptogram_len, "Card cryptogram: ");
*session = new_session;
if (context)
*context = new_session->context;
return YHR_SUCCESS;
bcse_failure:
// Only clear and free if we didn't reuse the session
if (new_session != *session) {
insecure_memzero(new_session, sizeof(yh_session));
free(new_session);
new_session = NULL;
}
DBG_ERR("%s", yh_strerror(yrc));
return yrc;
}
yh_rc yh_finish_create_session_ext(yh_connector *connector, yh_session *session,
const uint8_t *key_senc, size_t key_senc_len,
const uint8_t *key_smac, size_t key_smac_len,
const uint8_t *key_srmac,
size_t key_srmac_len,
uint8_t *card_cryptogram,
size_t card_cryptogram_len) {
if (connector != session->s.parent) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
return yh_finish_create_session(session, key_senc, key_senc_len, key_smac,
key_smac_len, key_srmac, key_srmac_len,
card_cryptogram, card_cryptogram_len);
}
yh_rc yh_finish_create_session(yh_session *session, const uint8_t *key_senc,
size_t key_senc_len, const uint8_t *key_smac,
size_t key_smac_len, const uint8_t *key_srmac,
size_t key_srmac_len, uint8_t *card_cryptogram,
size_t card_cryptogram_len) {
if (session == NULL || key_senc == NULL || key_senc_len != SCP_KEY_LEN ||
key_smac == NULL || key_smac_len != SCP_KEY_LEN || key_srmac == NULL ||
key_srmac_len != SCP_KEY_LEN || card_cryptogram == NULL) {
DBG_ERR("%s", yh_strerror(YHR_INVALID_PARAMETERS));
return YHR_INVALID_PARAMETERS;
}
if (session->s.s_enc != key_senc)
memcpy(session->s.s_enc, key_senc, SCP_KEY_LEN);
if (session->s.s_mac != key_smac)
memcpy(session->s.s_mac, key_smac, SCP_KEY_LEN);
if (session->s.s_rmac != key_srmac)
memcpy(session->s.s_rmac, key_srmac, SCP_KEY_LEN);
DBG_INT(session->s.s_enc, SCP_KEY_LEN, "S-ENC: ");
DBG_INT(session->s.s_mac, SCP_KEY_LEN, "S-MAC: ");
DBG_INT(session->s.s_rmac, SCP_KEY_LEN, "S-RMAC: ");
if (card_cryptogram_len == SCP_KEY_LEN) {
// Validation of receipt is assumed to be done externally
// since it can't be calculated from session keys
// Initial mac chaining value is the receipt
memcpy(session->s.mac_chaining_value, card_cryptogram, SCP_PRF_LEN);
} else if (card_cryptogram_len == SCP_CARD_CRYPTO_LEN) {
memset(session->s.mac_chaining_value, 0, SCP_PRF_LEN);
// Verify card cryptogram
uint8_t computed_cryptogram[SCP_CARD_CRYPTO_LEN];
yh_rc yrc =
compute_cryptogram(session->s.s_mac, SCP_KEY_LEN, SCP_CARD_CRYPTOGRAM,
session->context, SCP_CARD_CRYPTO_LEN * 8,
computed_cryptogram);
if (yrc != YHR_SUCCESS) {
DBG_ERR("%s", yh_strerror(yrc));
return yrc;
}