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feat: HMAC support in Crypto APIs

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This commit is contained in:
Jon Bonazza
2020-11-14 04:42:47 -08:00
parent ed2f84735b
commit d5925fd522
13 changed files with 480 additions and 4 deletions
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47
core/crypto/crypto.cpp
View File

@ -65,6 +65,22 @@ void X509Certificate::_bind_methods() {
ClassDB::bind_method(D_METHOD("load", "path"), &X509Certificate::load);
}
/// HMACContext
void HMACContext::_bind_methods() {
ClassDB::bind_method(D_METHOD("start", "hash_type", "key"), &HMACContext::start);
ClassDB::bind_method(D_METHOD("update", "data"), &HMACContext::update);
ClassDB::bind_method(D_METHOD("finish"), &HMACContext::finish);
}
HMACContext *(*HMACContext::_create)() = nullptr;
HMACContext *HMACContext::create() {
if (_create) {
return _create();
}
ERR_FAIL_V_MSG(nullptr, "HMACContext is not available when the mbedtls module is disabled.");
}
/// Crypto
void (*Crypto::_load_default_certificates)(String p_path) = nullptr;
@ -82,6 +98,35 @@ void Crypto::load_default_certificates(String p_path) {
}
}
PackedByteArray Crypto::hmac_digest(HashingContext::HashType p_hash_type, PackedByteArray p_key, PackedByteArray p_msg) {
Ref<HMACContext> ctx = Ref<HMACContext>(HMACContext::create());
ERR_FAIL_COND_V_MSG(ctx.is_null(), PackedByteArray(), "HMAC is not available witout mbedtls module.");
Error err = ctx->start(p_hash_type, p_key);
ERR_FAIL_COND_V(err != OK, PackedByteArray());
err = ctx->update(p_msg);
ERR_FAIL_COND_V(err != OK, PackedByteArray());
return ctx->finish();
}
// Compares two HMACS for equality without leaking timing information in order to prevent timing attakcs.
// @see: https://paragonie.com/blog/2015/11/preventing-timing-attacks-on-string-comparison-with-double-hmac-strategy
bool Crypto::constant_time_compare(PackedByteArray p_trusted, PackedByteArray p_received) {
const uint8_t *t = p_trusted.ptr();
const uint8_t *r = p_received.ptr();
int tlen = p_trusted.size();
int rlen = p_received.size();
// If the lengths are different then nothing else matters.
if (tlen != rlen) {
return false;
}
uint8_t v = 0;
for (int i = 0; i < tlen; i++) {
v |= t[i] ^ r[i];
}
return v == 0;
}
void Crypto::_bind_methods() {
ClassDB::bind_method(D_METHOD("generate_random_bytes", "size"), &Crypto::generate_random_bytes);
ClassDB::bind_method(D_METHOD("generate_rsa", "size"), &Crypto::generate_rsa);
@ -90,6 +135,8 @@ void Crypto::_bind_methods() {
ClassDB::bind_method(D_METHOD("verify", "hash_type", "hash", "signature", "key"), &Crypto::verify);
ClassDB::bind_method(D_METHOD("encrypt", "key", "plaintext"), &Crypto::encrypt);
ClassDB::bind_method(D_METHOD("decrypt", "key", "ciphertext"), &Crypto::decrypt);
ClassDB::bind_method(D_METHOD("hmac_digest", "hash_type", "key", "msg"), &Crypto::hmac_digest);
ClassDB::bind_method(D_METHOD("constant_time_compare", "trusted", "received"), &Crypto::constant_time_compare);
}
/// Resource loader/saver

23
core/crypto/crypto.h
View File

@ -67,6 +67,23 @@ public:
virtual Error save(String p_path) = 0;
};
class HMACContext : public Reference {
GDCLASS(HMACContext, Reference);
protected:
static void _bind_methods();
static HMACContext *(*_create)();
public:
static HMACContext *create();
virtual Error start(HashingContext::HashType p_hash_type, PackedByteArray p_key) = 0;
virtual Error update(PackedByteArray p_data) = 0;
virtual PackedByteArray finish() = 0;
HMACContext() {}
};
class Crypto : public Reference {
GDCLASS(Crypto, Reference);
@ -88,6 +105,12 @@ public:
virtual Vector<uint8_t> encrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_plaintext) = 0;
virtual Vector<uint8_t> decrypt(Ref<CryptoKey> p_key, Vector<uint8_t> p_ciphertext) = 0;
PackedByteArray hmac_digest(HashingContext::HashType p_hash_type, PackedByteArray p_key, PackedByteArray p_msg);
// Compares two PackedByteArrays for equality without leaking timing information in order to prevent timing attacks.
// @see: https://paragonie.com/blog/2015/11/preventing-timing-attacks-on-string-comparison-with-double-hmac-strategy
bool constant_time_compare(PackedByteArray p_trusted, PackedByteArray p_received);
Crypto() {}
};