/**

* @file src/crypto.cpp

* @brief Definitions for cryptography functions.

*/

// lib includes

#include <openssl/pem.h>

#include <openssl/rsa.h>

// local includes

#include "crypto.h"

namespace crypto {

using asn1_string_t = util::safe_ptr<ASN1_STRING, ASN1_STRING_free>;

cert_chain_t::cert_chain_t():

_certs {},

_cert_ctx {X509_STORE_CTX_new()} {

}

void cert_chain_t::add(x509_t &&cert) {

x509_store_t x509_store {X509_STORE_new()};

X509_STORE_add_cert(x509_store.get(), cert.get());

_certs.emplace_back(std::make_pair(std::move(cert), std::move(x509_store)));

}

void cert_chain_t::clear() {

_certs.clear();

}

std::string subject_name(const X509 *x509) {

if (!x509) {

return {};

}

const auto *name = X509_get_subject_name(x509);

if (!name) {

return {};

}

char subject_name[256] {};

if (!X509_NAME_oneline(name, subject_name, sizeof(subject_name))) {

return {};

}

return subject_name;

}

static int openssl_verify_cb(int ok, X509_STORE_CTX *ctx) {

int err_code = X509_STORE_CTX_get_error(ctx);

switch (err_code) {

// Expired or not-yet-valid certificates are fine. Sometimes Moonlight is running on embedded devices

// that don't have accurate clocks (or haven't yet synchronized by the time Moonlight first runs).

// This behavior also matches what GeForce Experience does.

case X509_V_ERR_CERT_NOT_YET_VALID:

case X509_V_ERR_CERT_HAS_EXPIRED:

return 1;

default:

return ok;

}

}

/**

* @brief Verify the certificate chain.

* When certificates from two or more instances of Moonlight have been added to x509_store_t,

* only one of them will be verified by X509_verify_cert, resulting in only a single instance of

* Moonlight to be able to use Sunshine

*

* To circumvent this, x509_store_t instance will be created for each instance of the certificates.

* @param cert The certificate to verify.

* @return nullptr if the certificate is valid, otherwise an error string.

*/

const char *cert_chain_t::verify(x509_t::element_type *cert) {

int err_code = 0;

for (auto &[_, x509_store] : _certs) {

auto fg = util::fail_guard([this]() {

X509_STORE_CTX_cleanup(_cert_ctx.get());

});

X509_STORE_CTX_init(_cert_ctx.get(), x509_store.get(), cert, nullptr);

X509_STORE_CTX_set_verify_cb(_cert_ctx.get(), openssl_verify_cb);

// We don't care to validate the entire chain for the purposes of client auth.

// Some versions of clients forked from Moonlight Embedded produce client certs

// that OpenSSL doesn't detect as self-signed due to some X509v3 extensions.

X509_STORE_CTX_set_flags(_cert_ctx.get(), X509_V_FLAG_PARTIAL_CHAIN);

auto err = X509_verify_cert(_cert_ctx.get());

if (err == 1) {

return nullptr;

}

err_code = X509_STORE_CTX_get_error(_cert_ctx.get());

if (err_code != X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT && err_code != X509_V_ERR_INVALID_CA) {

return X509_verify_cert_error_string(err_code);

}

}

return X509_verify_cert_error_string(err_code);

}

namespace cipher {

static int init_decrypt_gcm(cipher_ctx_t &ctx, aes_t *key, aes_t *iv, bool padding) {

ctx.reset(EVP_CIPHER_CTX_new());

if (!ctx) {

return -1;

}

if (EVP_DecryptInit_ex(ctx.get(), EVP_aes_128_gcm(), nullptr, nullptr, nullptr) != 1) {

return -1;

}

if (EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_IVLEN, (int) iv->size(), nullptr) != 1) {

return -1;

}

if (EVP_DecryptInit_ex(ctx.get(), nullptr, nullptr, key->data(), iv->data()) != 1) {

return -1;

}

EVP_CIPHER_CTX_set_padding(ctx.get(), padding);

return 0;

}

static int init_encrypt_gcm(cipher_ctx_t &ctx, aes_t *key, aes_t *iv, bool padding) {

ctx.reset(EVP_CIPHER_CTX_new());

// Gen 7 servers use 128-bit AES ECB

if (EVP_EncryptInit_ex(ctx.get(), EVP_aes_128_gcm(), nullptr, nullptr, nullptr) != 1) {

return -1;

}

if (EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_IVLEN, (int) iv->size(), nullptr) != 1) {

return -1;

}

if (EVP_EncryptInit_ex(ctx.get(), nullptr, nullptr, key->data(), iv->data()) != 1) {

return -1;

}

EVP_CIPHER_CTX_set_padding(ctx.get(), padding);

return 0;

}

static int init_encrypt_cbc(cipher_ctx_t &ctx, aes_t *key, aes_t *iv, bool padding) {

ctx.reset(EVP_CIPHER_CTX_new());

// Gen 7 servers use 128-bit AES ECB

if (EVP_EncryptInit_ex(ctx.get(), EVP_aes_128_cbc(), nullptr, key->data(), iv->data()) != 1) {

return -1;

}

EVP_CIPHER_CTX_set_padding(ctx.get(), padding);

return 0;

}

int gcm_t::decrypt(const std::string_view &tagged_cipher, std::vector<std::uint8_t> &plaintext, aes_t *iv) {

if (!decrypt_ctx && init_decrypt_gcm(decrypt_ctx, &key, iv, padding)) {

return -1;

}

// Calling with cipher == nullptr results in a parameter change

// without requiring a reallocation of the internal cipher ctx.

if (EVP_DecryptInit_ex(decrypt_ctx.get(), nullptr, nullptr, nullptr, iv->data()) != 1) {

return false;

}

auto cipher = tagged_cipher.substr(tag_size);

auto tag = tagged_cipher.substr(0, tag_size);

plaintext.resize(round_to_pkcs7_padded(cipher.size()));

int final_outlen;

int update_outlen;

if (EVP_DecryptUpdate(decrypt_ctx.get(), plaintext.data(), &update_outlen, (const std::uint8_t *) cipher.data(), (int) cipher.size()) != 1) {

return -1;

}

if (EVP_CIPHER_CTX_ctrl(decrypt_ctx.get(), EVP_CTRL_GCM_SET_TAG, (int) tag.size(), const_cast<char *>(tag.data())) != 1) {

return -1;

}

if (EVP_DecryptFinal_ex(decrypt_ctx.get(), plaintext.data() + update_outlen, &final_outlen) != 1) {

return -1;

}

plaintext.resize(update_outlen + final_outlen);

return 0;

}

/**

* This function encrypts the given plaintext using the AES key in GCM mode. The initialization vector (IV) is also provided.

* The function handles the creation and initialization of the encryption context, and manages the encryption process.

* The resulting ciphertext and the GCM tag are written into the tagged_cipher buffer.

*/

int gcm_t::encrypt(const std::string_view &plaintext, std::uint8_t *tag, std::uint8_t *ciphertext, aes_t *iv) {

if (!encrypt_ctx && init_encrypt_gcm(encrypt_ctx, &key, iv, padding)) {

return -1;

}

// Calling with cipher == nullptr results in a parameter change

// without requiring a reallocation of the internal cipher ctx.

if (EVP_EncryptInit_ex(encrypt_ctx.get(), nullptr, nullptr, nullptr, iv->data()) != 1) {

return -1;

}

int final_outlen;

int update_outlen;

// Encrypt into the caller's buffer

if (EVP_EncryptUpdate(encrypt_ctx.get(), ciphertext, &update_outlen, (const std::uint8_t *) plaintext.data(), (int) plaintext.size()) != 1) {

return -1;

}

// GCM encryption won't ever fill ciphertext here but we have to call it anyway

if (EVP_EncryptFinal_ex(encrypt_ctx.get(), ciphertext + update_outlen, &final_outlen) != 1) {

return -1;

}

if (EVP_CIPHER_CTX_ctrl(encrypt_ctx.get(), EVP_CTRL_GCM_GET_TAG, tag_size, tag) != 1) {

return -1;

}

return update_outlen + final_outlen;

}

int gcm_t::encrypt(const std::string_view &plaintext, std::uint8_t *tagged_cipher, aes_t *iv) {

// This overload handles the common case of [GCM tag][cipher text] buffer layout

return encrypt(plaintext, tagged_cipher, tagged_cipher + tag_size, iv);

}

int ecb_t::decrypt(const std::string_view &cipher, std::vector<std::uint8_t> &plaintext) {

auto fg = util::fail_guard([this]() {

EVP_CIPHER_CTX_reset(decrypt_ctx.get());

});

// Gen 7 servers use 128-bit AES ECB

if (EVP_DecryptInit_ex(decrypt_ctx.get(), EVP_aes_128_ecb(), nullptr, key.data(), nullptr) != 1) {

return -1;

}

EVP_CIPHER_CTX_set_padding(decrypt_ctx.get(), padding);

plaintext.resize(round_to_pkcs7_padded(cipher.size()));

int final_outlen;

int update_outlen;

if (EVP_DecryptUpdate(decrypt_ctx.get(), plaintext.data(), &update_outlen, (const std::uint8_t *) cipher.data(), (int) cipher.size()) != 1) {

return -1;

}

if (EVP_DecryptFinal_ex(decrypt_ctx.get(), plaintext.data() + update_outlen, &final_outlen) != 1) {

return -1;

}

plaintext.resize(update_outlen + final_outlen);

return 0;

}

int ecb_t::encrypt(const std::string_view &plaintext, std::vector<std::uint8_t> &cipher) {

auto fg = util::fail_guard([this]() {

EVP_CIPHER_CTX_reset(encrypt_ctx.get());

});

// Gen 7 servers use 128-bit AES ECB

if (EVP_EncryptInit_ex(encrypt_ctx.get(), EVP_aes_128_ecb(), nullptr, key.data(), nullptr) != 1) {

return -1;

}

EVP_CIPHER_CTX_set_padding(encrypt_ctx.get(), padding);

cipher.resize(round_to_pkcs7_padded(plaintext.size()));

int final_outlen;

int update_outlen;

// Encrypt into the caller's buffer

if (EVP_EncryptUpdate(encrypt_ctx.get(), cipher.data(), &update_outlen, (const std::uint8_t *) plaintext.data(), (int) plaintext.size()) != 1) {

return -1;

}

if (EVP_EncryptFinal_ex(encrypt_ctx.get(), cipher.data() + update_outlen, &final_outlen) != 1) {

return -1;

}

cipher.resize(update_outlen + final_outlen);

return 0;

}

/**

* This function encrypts the given plaintext using the AES key in CBC mode. The initialization vector (IV) is also provided.

* The function handles the creation and initialization of the encryption context, and manages the encryption process.

* The resulting ciphertext is written into the cipher buffer.

*/

int cbc_t::encrypt(const std::string_view &plaintext, std::uint8_t *cipher, aes_t *iv) {

if (!encrypt_ctx && init_encrypt_cbc(encrypt_ctx, &key, iv, padding)) {

return -1;

}

// Calling with cipher == nullptr results in a parameter change

// without requiring a reallocation of the internal cipher ctx.

if (EVP_EncryptInit_ex(encrypt_ctx.get(), nullptr, nullptr, nullptr, iv->data()) != 1) {

return false;

}

int final_outlen;

int update_outlen;

// Encrypt into the caller's buffer

if (EVP_EncryptUpdate(encrypt_ctx.get(), cipher, &update_outlen, (const std::uint8_t *) plaintext.data(), (int) plaintext.size()) != 1) {

return -1;

}

if (EVP_EncryptFinal_ex(encrypt_ctx.get(), cipher + update_outlen, &final_outlen) != 1) {

return -1;

}

return update_outlen + final_outlen;

}

ecb_t::ecb_t(const aes_t &key, bool padding):

cipher_t {EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_new(), key, padding} {

}

cbc_t::cbc_t(const aes_t &key, bool padding):

cipher_t {nullptr, nullptr, key, padding} {

}

gcm_t::gcm_t(const crypto::aes_t &key, bool padding):

cipher_t {nullptr, nullptr, key, padding} {

}

} // namespace cipher

aes_t gen_aes_key(const std::array<uint8_t, 16> &salt, const std::string_view &pin) {

aes_t key(16);

std::string salt_pin;

salt_pin.reserve(salt.size() + pin.size());

salt_pin.insert(std::end(salt_pin), std::begin(salt), std::end(salt));

salt_pin.insert(std::end(salt_pin), std::begin(pin), std::end(pin));

auto hsh = hash(salt_pin);

std::copy(std::begin(hsh), std::begin(hsh) + key.size(), std::begin(key));

return key;

}

sha256_t hash(const std::string_view &plaintext) {

sha256_t hsh;

EVP_Digest(plaintext.data(), plaintext.size(), hsh.data(), nullptr, EVP_sha256(), nullptr);

return hsh;

}

x509_t x509(const std::string_view &x) {

bio_t io {BIO_new(BIO_s_mem())};

BIO_write(io.get(), x.data(), (int) x.size());

x509_t p;

PEM_read_bio_X509(io.get(), &p, nullptr, nullptr);

return p;

}

pkey_t pkey(const std::string_view &k) {

bio_t io {BIO_new(BIO_s_mem())};

BIO_write(io.get(), k.data(), (int) k.size());

pkey_t p = nullptr;

PEM_read_bio_PrivateKey(io.get(), &p, nullptr, nullptr);

return p;

}

std::string pem(x509_t &x509) {

bio_t bio {BIO_new(BIO_s_mem())};

PEM_write_bio_X509(bio.get(), x509.get());

BUF_MEM *mem_ptr;

BIO_get_mem_ptr(bio.get(), &mem_ptr);

return {mem_ptr->data, mem_ptr->length};

}

std::string pem(pkey_t &pkey) {

bio_t bio {BIO_new(BIO_s_mem())};

PEM_write_bio_PrivateKey(bio.get(), pkey.get(), nullptr, nullptr, 0, nullptr, nullptr);

BUF_MEM *mem_ptr;

BIO_get_mem_ptr(bio.get(), &mem_ptr);

return {mem_ptr->data, mem_ptr->length};

}

std::string_view signature(const X509 *x) {

const ASN1_BIT_STRING *asn1 = nullptr;

X509_get0_signature(&asn1, nullptr, x);

if (!asn1) {

return {};

}

return {(const char *) asn1->data, (std::size_t) asn1->length};

}

std::string_view signature(const x509_t &x) {

return signature(x.get());

}

std::string rand(std::size_t bytes) {

std::string r;

r.resize(bytes);

RAND_bytes((uint8_t *) r.data(), (int) r.size());

return r;

}

std::vector<uint8_t> sign(const pkey_t &pkey, const std::string_view &data, const EVP_MD *md) {

md_ctx_t ctx {EVP_MD_CTX_create()};

if (EVP_DigestSignInit(ctx.get(), nullptr, md, nullptr, (EVP_PKEY *) pkey.get()) != 1) {

return {};

}

if (EVP_DigestSignUpdate(ctx.get(), data.data(), data.size()) != 1) {

return {};

}

std::size_t slen;

if (EVP_DigestSignFinal(ctx.get(), nullptr, &slen) != 1) {

return {};

}

std::vector<uint8_t> digest(slen);

if (EVP_DigestSignFinal(ctx.get(), digest.data(), &slen) != 1) {

return {};

}

return digest;

}

creds_t gen_creds(const std::string_view &cn, std::uint32_t key_bits) {

x509_t x509 {X509_new()};

pkey_ctx_t ctx {EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, nullptr)};

pkey_t pkey;

EVP_PKEY_keygen_init(ctx.get());

EVP_PKEY_CTX_set_rsa_keygen_bits(ctx.get(), key_bits);

EVP_PKEY_keygen(ctx.get(), &pkey);

X509_set_version(x509.get(), 2);

// Generate a real serial number to avoid SEC_ERROR_REUSED_ISSUER_AND_SERIAL with Firefox

bignum_t serial {BN_new()};

BN_rand(serial.get(), 159, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY); // 159 bits to fit in 20 bytes in DER format

BN_set_negative(serial.get(), 0); // Serial numbers must be positive

BN_to_ASN1_INTEGER(serial.get(), X509_get_serialNumber(x509.get()));

constexpr auto year = 60 * 60 * 24 * 365;

#if OPENSSL_VERSION_NUMBER < 0x10100000L

X509_gmtime_adj(X509_get_notBefore(x509.get()), 0);

X509_gmtime_adj(X509_get_notAfter(x509.get()), 20 * year);

#else

asn1_string_t not_before {ASN1_STRING_dup(X509_get0_notBefore(x509.get()))};

asn1_string_t not_after {ASN1_STRING_dup(X509_get0_notAfter(x509.get()))};

X509_gmtime_adj(not_before.get(), 0);

X509_gmtime_adj(not_after.get(), 20 * year);

X509_set1_notBefore(x509.get(), not_before.get());

X509_set1_notAfter(x509.get(), not_after.get());

#endif

X509_set_pubkey(x509.get(), pkey.get());

auto name = X509_get_subject_name(x509.get());

X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (const std::uint8_t *) cn.data(), (int) cn.size(), -1, 0);

X509_set_issuer_name(x509.get(), name);

X509_sign(x509.get(), pkey.get(), EVP_sha256());

return {pem(x509), pem(pkey)};

}

std::vector<uint8_t> sign256(const pkey_t &pkey, const std::string_view &data) {

return sign(pkey, data, EVP_sha256());

}

bool verify(const x509_t &x509, const std::string_view &data, const std::string_view &signature, const EVP_MD *md) {

auto pkey = X509_get0_pubkey(x509.get());

md_ctx_t ctx {EVP_MD_CTX_create()};

if (EVP_DigestVerifyInit(ctx.get(), nullptr, md, nullptr, pkey) != 1) {

return false;

}

if (EVP_DigestVerifyUpdate(ctx.get(), data.data(), data.size()) != 1) {

return false;

}

if (EVP_DigestVerifyFinal(ctx.get(), (const uint8_t *) signature.data(), signature.size()) != 1) {

return false;

}

return true;

}

bool verify256(const x509_t &x509, const std::string_view &data, const std::string_view &signature) {

return verify(x509, data, signature, EVP_sha256());

}

void md_ctx_destroy(EVP_MD_CTX *ctx) {

EVP_MD_CTX_destroy(ctx);

}

std::string rand_alphabet(std::size_t bytes, const std::string_view &alphabet) {

auto value = rand(bytes);

for (std::size_t i = 0; i != value.size(); ++i) {

value[i] = alphabet[value[i] % alphabet.length()];

}

return value;

}

} // namespace crypto