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#include "libfilezilla/encryption.hpp"
#include "libfilezilla/encode.hpp"
#include "libfilezilla/hash.hpp"
#include "libfilezilla/util.hpp"
#include <cstring>
#include <nettle/aes.h>
#include <nettle/ctr.h>
#include <nettle/curve25519.h>
#include <nettle/gcm.h>
#include <nettle/memops.h>
#include <nettle/sha2.h>
#include <nettle/version.h>
namespace fz {
std::string public_key::to_base64(bool pad) const
{
auto raw = std::string(key_.cbegin(), key_.cend());
raw += std::string(salt_.cbegin(), salt_.cend());
return base64_encode(raw, base64_type::standard, pad);
}
namespace {
template<typename T>
public_key from_base64_impl(T const& base64)
{
public_key ret;
auto raw = base64_decode(base64);
if (raw.size() == public_key::key_size + public_key::salt_size) {
auto p = reinterpret_cast<uint8_t const*>(raw.data());
ret.key_.assign(p, p + public_key::key_size);
ret.salt_.assign(p + public_key::key_size, p + public_key::key_size + public_key::salt_size);
}
return ret;
}
}
public_key public_key::from_base64(std::string_view const& base64)
{
return from_base64_impl(base64);
}
public_key public_key::from_base64(std::wstring_view const& base64)
{
return from_base64_impl(base64);
}
private_key private_key::generate()
{
private_key ret;
ret.key_ = random_bytes(key_size);
ret.key_[0] &= 248;
ret.key_[31] &= 127;
ret.key_[31] |= 64;
ret.salt_ = random_bytes(salt_size);
return ret;
}
public_key private_key::pubkey() const
{
public_key ret;
if (*this) {
static const uint8_t nine[32]{
9, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0 };
ret.key_.resize(32);
nettle_curve25519_mul(ret.key_.data(), key_.data(), nine);
ret.salt_ = salt_;
}
return ret;
}
private_key private_key::from_password(std::vector<uint8_t> const& password, std::vector<uint8_t> const& salt, unsigned int iterations)
{
private_key ret;
if (!password.empty() && salt.size() == salt_size && iterations >= min_iterations) {
std::vector<uint8_t> key = pbkdf2_hmac_sha256(password, salt, 32, iterations);
key[0] &= 248;
key[31] &= 127;
key[31] |= 64;
ret.key_ = std::move(key);
ret.salt_ = salt;
}
return ret;
}
std::string private_key::to_base64(bool pad) const
{
auto raw = std::string(key_.cbegin(), key_.cend());
raw += std::string(salt_.cbegin(), salt_.cend());
return base64_encode(raw, base64_type::standard, pad);
}
private_key private_key::from_base64(std::string_view const& base64)
{
private_key ret;
auto raw = base64_decode(base64);
if (raw.size() == key_size + salt_size) {
auto p = reinterpret_cast<uint8_t const*>(raw.data());
ret.key_.assign(p, p + key_size);
ret.key_[0] &= 248;
ret.key_[31] &= 127;
ret.key_[31] |= 64;
ret.salt_.assign(p + key_size, p + key_size + salt_size);
}
return ret;
}
std::vector<uint8_t> private_key::shared_secret(public_key const& pub) const
{
std::vector<uint8_t> ret;
if (*this && pub) {
ret.resize(32);
nettle_curve25519_mul(ret.data(), key_.data(), pub.key_.data());
}
return ret;
}
namespace {
std::vector<uint8_t> encrypt(uint8_t const* plain, size_t size, public_key const& pub, uint8_t const* authenticated_data, size_t authenticated_data_size, bool authenticated)
{
std::vector<uint8_t> ret;
private_key ephemeral = private_key::generate();
public_key ephemeral_pub = ephemeral.pubkey();
if (pub && ephemeral && ephemeral_pub) {
// Generate shared secret from pub and ephemeral
std::vector<uint8_t> secret = ephemeral.shared_secret(pub);
// Derive AES2556 key and CTR nonce from shared secret
std::vector<uint8_t> const aes_key = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 0 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
if (authenticated) {
std::vector<uint8_t> iv = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 2 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
static_assert(SHA256_DIGEST_SIZE >= GCM_IV_SIZE, "iv too small");
iv.resize(GCM_IV_SIZE);
gcm_aes256_ctx ctx;
nettle_gcm_aes256_set_key(&ctx, aes_key.data());
nettle_gcm_aes256_set_iv(&ctx, GCM_IV_SIZE, iv.data());
if (authenticated_data_size) {
nettle_gcm_aes256_update(&ctx, authenticated_data_size, authenticated_data);
}
// Encrypt plaintext with AES256-GCM
ret.resize(public_key::key_size + public_key::salt_size + size + GCM_DIGEST_SIZE);
if (size) {
nettle_gcm_aes256_encrypt(&ctx, size, ret.data() + public_key::key_size + public_key::salt_size, plain);
}
// Return ephemeral_pub.key_||ephemeral_pub.salt_||ciphertext||tag
memcpy(ret.data(), ephemeral_pub.key_.data(), public_key::key_size);
memcpy(ret.data() + public_key::key_size, ephemeral_pub.salt_.data(), public_key::salt_size);
nettle_gcm_aes256_digest(&ctx, GCM_DIGEST_SIZE, ret.data() + public_key::key_size + public_key::salt_size + size);
}
else {
std::vector<uint8_t> ctr = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 1 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
aes256_ctx ctx;
nettle_aes256_set_encrypt_key(&ctx, aes_key.data());
// Encrypt plaintext with AES256-CTR
ret.resize(public_key::key_size + public_key::salt_size + size);
if (size) {
nettle_ctr_crypt(&ctx, reinterpret_cast<nettle_cipher_func*>(nettle_aes256_encrypt), 16, ctr.data(), size, ret.data() + public_key::key_size + public_key::salt_size, plain);
}
// Return ephemeral_pub.key_||ephemeral_pub.salt_||ciphertext
memcpy(ret.data(), ephemeral_pub.key_.data(), public_key::key_size);
memcpy(ret.data() + public_key::key_size, ephemeral_pub.salt_.data(), public_key::salt_size);
}
}
return ret;
}
}
std::vector<uint8_t> encrypt(uint8_t const* plain, size_t size, public_key const& pub, bool authenticated)
{
return encrypt(plain, size, pub, nullptr, 0, authenticated);
}
std::vector<uint8_t> encrypt(std::vector<uint8_t> const& plain, public_key const& pub, bool authenticated)
{
return encrypt(plain.data(), plain.size(), pub, nullptr, 0, authenticated);
}
std::vector<uint8_t> encrypt(std::string_view const& plain, public_key const& pub, bool authenticated)
{
return encrypt(reinterpret_cast<uint8_t const*>(plain.data()), plain.size(), pub, nullptr, 0, authenticated);
}
std::vector<uint8_t> encrypt(uint8_t const* plain, size_t size, public_key const& pub, uint8_t const* authenticated_data, size_t authenticated_data_size)
{
return encrypt(plain, size, pub, authenticated_data, authenticated_data_size, true);
}
std::vector<uint8_t> encrypt(std::vector<uint8_t> const& plain, public_key const& pub, std::vector<uint8_t> const& authenticated_data)
{
return encrypt(plain.data(), plain.size(), pub, authenticated_data.data(), authenticated_data.size(), true);
}
std::vector<uint8_t> encrypt(std::string_view const& plain, public_key const& pub, std::string_view const& authenticated_data)
{
return encrypt(reinterpret_cast<uint8_t const*>(plain.data()), plain.size(), pub, reinterpret_cast<uint8_t const*>(authenticated_data.data()), authenticated_data.size(), true);
}
namespace {
std::vector<uint8_t> decrypt(uint8_t const* cipher, size_t size, private_key const& priv, uint8_t const* authenticated_data, size_t authenticated_data_size, bool authenticated)
{
size_t const overhead = public_key::key_size + public_key::salt_size + (authenticated ? GCM_DIGEST_SIZE : 0);
std::vector<uint8_t> ret;
if (priv && size >= overhead && cipher) {
size_t const message_size = size - overhead;
// Extract ephemeral_pub from cipher
public_key ephemeral_pub;
ephemeral_pub.key_.resize(public_key::key_size);
ephemeral_pub.salt_.resize(public_key::salt_size);
memcpy(ephemeral_pub.key_.data(), cipher, public_key::key_size);
memcpy(ephemeral_pub.salt_.data(), cipher + public_key::key_size, public_key::salt_size);
// Generate shared secret from ephemeral_pub and priv
std::vector<uint8_t> const secret = priv.shared_secret(ephemeral_pub);
public_key const pub = priv.pubkey();
std::vector<uint8_t> const aes_key = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 0 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
if (authenticated) {
// Derive AES2556 key and GCM IV from shared secret
std::vector<uint8_t> iv = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 2 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
static_assert(SHA256_DIGEST_SIZE >= GCM_IV_SIZE, "iv too small");
iv.resize(GCM_IV_SIZE);
gcm_aes256_ctx ctx;
nettle_gcm_aes256_set_key(&ctx, aes_key.data());
nettle_gcm_aes256_set_iv(&ctx, GCM_IV_SIZE, iv.data());
if (authenticated_data_size) {
nettle_gcm_aes256_update(&ctx, authenticated_data_size, authenticated_data);
}
// Decrypt ciphertext with AES256-GCM
ret.resize(message_size);
if (message_size) {
nettle_gcm_aes256_decrypt(&ctx, message_size, ret.data(), cipher + public_key::key_size + public_key::salt_size);
}
// Last but not least, verify the tag
uint8_t tag[GCM_DIGEST_SIZE];
nettle_gcm_aes256_digest(&ctx, GCM_DIGEST_SIZE, tag);
if (!nettle_memeql_sec(tag, cipher + size - GCM_DIGEST_SIZE, GCM_DIGEST_SIZE)) {
ret.clear();
}
}
else {
// Derive AES2556 key and CTR nonce from shared secret
std::vector<uint8_t> ctr = hash_accumulator(hash_algorithm::sha256) << ephemeral_pub.salt_ << 1 << secret << ephemeral_pub.key_ << pub.key_ << pub.salt_;
aes256_ctx ctx;
nettle_aes256_set_encrypt_key(&ctx, aes_key.data());
// Decrypt ciphertext with AES256-CTR
ret.resize(message_size);
if (message_size) {
nettle_ctr_crypt(&ctx, reinterpret_cast<nettle_cipher_func*>(nettle_aes256_encrypt), 16, ctr.data(), ret.size(), ret.data(), cipher + public_key::key_size + public_key::salt_size);
}
}
}
// Return the plaintext
return ret;
}
}
std::vector<uint8_t> decrypt(uint8_t const* cipher, size_t size, private_key const& priv, bool authenticated)
{
return decrypt(cipher, size, priv, nullptr, 0, authenticated);
}
std::vector<uint8_t> decrypt(std::vector<uint8_t> const& cipher, private_key const& priv, bool authenticated)
{
return decrypt(cipher.data(), cipher.size(), priv, nullptr, 0, authenticated);
}
std::vector<uint8_t> decrypt(std::string_view const& cipher, private_key const& priv, bool authenticated)
{
return decrypt(reinterpret_cast<uint8_t const*>(cipher.data()), cipher.size(), priv, nullptr, 0, authenticated);
}
std::vector<uint8_t> decrypt(uint8_t const* cipher, size_t size, private_key const& priv, uint8_t const* authenticated_data, size_t authenticated_data_size)
{
return decrypt(cipher, size, priv, authenticated_data, authenticated_data_size, true);
}
std::vector<uint8_t> decrypt(std::vector<uint8_t> const& cipher, private_key const& priv, std::vector<uint8_t> const& authenticated_data)
{
return decrypt(cipher.data(), cipher.size(), priv, authenticated_data.data(), authenticated_data.size(), true);
}
std::vector<uint8_t> decrypt(std::string_view const& cipher, private_key const& priv, std::string_view const& authenticated_data)
{
return decrypt(reinterpret_cast<uint8_t const*>(cipher.data()), cipher.size(), priv, reinterpret_cast<uint8_t const*>(authenticated_data.data()), authenticated_data.size(), true);
}
symmetric_key symmetric_key::generate()
{
symmetric_key ret;
ret.key_ = random_bytes(key_size);
ret.salt_ = random_bytes(salt_size);
return ret;
}
symmetric_key symmetric_key::from_password(std::vector<uint8_t> const& password, std::vector<uint8_t> const& salt, unsigned int iterations)
{
symmetric_key ret;
if (!password.empty() && salt.size() == salt_size && iterations >= min_iterations) {
std::vector<uint8_t> key = pbkdf2_hmac_sha256(password, salt, 32, iterations);
ret.key_ = std::move(key);
ret.salt_ = salt;
}
return ret;
}
std::string symmetric_key::to_base64(bool pad) const
{
auto raw = std::string(key_.cbegin(), key_.cend());
raw += std::string(salt_.cbegin(), salt_.cend());
return base64_encode(raw, base64_type::standard, pad);
}
symmetric_key symmetric_key::from_base64(std::string_view const& base64)
{
symmetric_key ret;
auto raw = base64_decode(base64);
if (raw.size() == key_size + salt_size) {
auto p = reinterpret_cast<uint8_t const*>(raw.data());
ret.key_.assign(p, p + key_size);
ret.salt_.assign(p + key_size, p + key_size + salt_size);
}
return ret;
}
symmetric_key symmetric_key::from_base64(std::wstring_view const& base64)
{
symmetric_key ret;
auto raw = base64_decode(base64);
if (raw.size() == key_size + salt_size) {
auto p = reinterpret_cast<uint8_t const*>(raw.data());
ret.key_.assign(p, p + key_size);
ret.salt_.assign(p + key_size, p + key_size + salt_size);
}
return ret;
}
std::vector<uint8_t> const& symmetric_key::key() const
{
return key_;
}
std::vector<uint8_t> symmetric_key::encrypt_key(fz::public_key const& kek)
{
if (key_.empty() || salt_.empty() || !kek) {
return std::vector<uint8_t>();
}
std::vector<uint8_t> tmp;
tmp.resize(key_.size() + salt_.size());
memcpy(tmp.data(), key_.data(), key_.size());
memcpy(tmp.data() + key_.size(), salt_.data(), salt_.size());
return fz::encrypt(tmp, kek);
}
symmetric_key symmetric_key::decrypt_key(std::vector<uint8_t> const& encrypted, fz::private_key const& kek)
{
symmetric_key ret;
auto raw = fz::decrypt(encrypted, kek);
if (raw.size() == key_size + salt_size) {
auto p = reinterpret_cast<uint8_t const*>(raw.data());
ret.key_.assign(p, p + key_size);
ret.salt_.assign(p + key_size, p + key_size + salt_size);
}
return ret;
}
bool operator==(symmetric_key const& lhs, symmetric_key const& rhs)
{
if (!lhs) {
return !rhs;
}
else if (!rhs) {
return false;
}
// By definition both key and salt are non-empty and have the same size in each.
return nettle_memeql_sec(lhs.salt().data(), rhs.salt().data(), lhs.salt().size()) && nettle_memeql_sec(lhs.key().data(), rhs.key().data(), lhs.key().size());
}
size_t symmetric_key::encryption_overhead()
{
return symmetric_key::salt_size + GCM_DIGEST_SIZE;
}
std::vector<uint8_t> encrypt(uint8_t const* plain, size_t size, symmetric_key const& key, uint8_t const* authenticated_data, size_t authenticated_data_size)
{
std::vector<uint8_t> ret;
if (key) {
// Generate per-message nonce
auto nonce = random_bytes(symmetric_key::salt_size);
// Derive AES2556 key and IV from symmetric key and nonce
std::vector<uint8_t> const aes_key = hash_accumulator(hash_algorithm::sha256) << key.salt() << 3 << key.key() << nonce;
std::vector<uint8_t> iv = hash_accumulator(hash_algorithm::sha256) << key.salt() << 4 << key.key() << nonce;
static_assert(SHA256_DIGEST_SIZE >= GCM_IV_SIZE, "iv too small");
iv.resize(GCM_IV_SIZE);
gcm_aes256_ctx ctx;
nettle_gcm_aes256_set_key(&ctx, aes_key.data());
nettle_gcm_aes256_set_iv(&ctx, GCM_IV_SIZE, iv.data());
if (authenticated_data_size) {
nettle_gcm_aes256_update(&ctx, authenticated_data_size, authenticated_data);
}
// Encrypt plaintext with AES256-GCM
ret.resize(symmetric_key::salt_size + size + GCM_DIGEST_SIZE);
if (size) {
nettle_gcm_aes256_encrypt(&ctx, size, ret.data() + symmetric_key::salt_size, plain);
}
// Return nonce||ciphertext||tag
memcpy(ret.data(), nonce.data(), symmetric_key::salt_size);
nettle_gcm_aes256_digest(&ctx, GCM_DIGEST_SIZE, ret.data() + symmetric_key::salt_size + size);
}
return ret;
}
std::vector<uint8_t> encrypt(uint8_t const* plain, size_t size, symmetric_key const& key)
{
return encrypt(plain, size, key, nullptr, 0);
}
std::vector<uint8_t> encrypt(std::vector<uint8_t> const& plain, symmetric_key const& key)
{
return encrypt(plain.data(), plain.size(), key, nullptr, 0);
}
std::vector<uint8_t> encrypt(std::string_view const& plain, symmetric_key const& key)
{
return encrypt(reinterpret_cast<uint8_t const*>(plain.data()), plain.size(), key, nullptr, 0);
}
std::vector<uint8_t> encrypt(std::vector<uint8_t> const& plain, symmetric_key const& key, std::vector<uint8_t> const& authenticated_data)
{
return encrypt(plain.data(), plain.size(), key, authenticated_data.data(), authenticated_data.size());
}
std::vector<uint8_t> encrypt(std::string_view const& plain, symmetric_key const& key, std::string_view const& authenticated_data)
{
return encrypt(reinterpret_cast<uint8_t const*>(plain.data()), plain.size(), key, reinterpret_cast<uint8_t const*>(authenticated_data.data()), authenticated_data.size());
}
std::vector<uint8_t> decrypt(uint8_t const* cipher, size_t size, symmetric_key const& key, uint8_t const* authenticated_data, size_t authenticated_data_size)
{
std::vector<uint8_t> ret;
size_t const overhead = symmetric_key::encryption_overhead();
if (key && size >= overhead && cipher) {
size_t const message_size = size - overhead;
// Extract per-message nonce from cipher
std::basic_string_view<uint8_t> const nonce(cipher, symmetric_key::salt_size);
// Derive AES2556 key and IV from symmetric key and nonce
std::vector<uint8_t> const aes_key = hash_accumulator(hash_algorithm::sha256) << key.salt() << 3 << key.key() << nonce;
std::vector<uint8_t> iv = hash_accumulator(hash_algorithm::sha256) << key.salt() << 4 << key.key() << nonce;
static_assert(SHA256_DIGEST_SIZE >= GCM_IV_SIZE, "iv too small");
iv.resize(GCM_IV_SIZE);
gcm_aes256_ctx ctx;
nettle_gcm_aes256_set_key(&ctx, aes_key.data());
nettle_gcm_aes256_set_iv(&ctx, GCM_IV_SIZE, iv.data());
if (authenticated_data_size) {
nettle_gcm_aes256_update(&ctx, authenticated_data_size, authenticated_data);
}
// Decrypt ciphertext with AES256-GCM
ret.resize(message_size);
if (message_size) {
nettle_gcm_aes256_decrypt(&ctx, message_size, ret.data(), cipher + symmetric_key::salt_size);
}
// Last but not least, verify the tag
uint8_t tag[GCM_DIGEST_SIZE];
nettle_gcm_aes256_digest(&ctx, GCM_DIGEST_SIZE, tag);
if (!nettle_memeql_sec(tag, cipher + size - GCM_DIGEST_SIZE, GCM_DIGEST_SIZE)) {
ret.clear();
}
}
// Return the plaintext
return ret;
}
std::vector<uint8_t> decrypt(uint8_t const* cipher, size_t size, symmetric_key const& key)
{
return decrypt(cipher, size, key, nullptr, 0);
}
std::vector<uint8_t> decrypt(std::vector<uint8_t> const& cipher, symmetric_key const& key)
{
return decrypt(cipher.data(), cipher.size(), key, nullptr, 0);
}
std::vector<uint8_t> decrypt(std::string_view const& cipher, symmetric_key const& key)
{
return decrypt(reinterpret_cast<uint8_t const*>(cipher.data()), cipher.size(), key, nullptr, 0);
}
std::vector<uint8_t> decrypt(std::vector<uint8_t> const& cipher, symmetric_key const& key, std::vector<uint8_t> const& authenticated_data)
{
return decrypt(cipher.data(), cipher.size(), key, authenticated_data.data(), authenticated_data.size());
}
std::vector<uint8_t> decrypt(std::string_view const& cipher, symmetric_key const& key, std::string_view const& authenticated_data)
{
return decrypt(reinterpret_cast<uint8_t const*>(cipher.data()), cipher.size(), key, reinterpret_cast<uint8_t const*>(authenticated_data.data()), authenticated_data.size());
}
}
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