Add signature validation to TMD

externals/cryptopp/CMakeLists.txt

@@ -158,6 +158,7 @@ set(cryptopp_SOURCES
         cryptopp/neon-simd.cpp
         cryptopp/oaep.cpp
         cryptopp/osrng.cpp
+        cryptopp/pkcspad.cpp
         cryptopp/pubkey.cpp
         cryptopp/queue.cpp
         cryptopp/randpool.cpp
@@ -165,6 +166,7 @@ set(cryptopp_SOURCES
         cryptopp/rijndael-simd.cpp
         cryptopp/rijndael.cpp
         cryptopp/rng.cpp
+        cryptopp/rsa.cpp
         cryptopp/sha-simd.cpp
         cryptopp/sha.cpp
         cryptopp/sse-simd.cpp

src/core/ncch/certificate.cpp

@@ -4,8 +4,9 @@
 
 #include <cstring>
 #include <unordered_map>
-#include <cryptopp/sha.h>
+#include <cryptopp/integer.h>
 #include "common/alignment.h"
+#include "common/assert.h"
 #include "common/file_util.h"
 #include "common/logging/log.h"
 #include "common/string_util.h"
@@ -94,6 +95,18 @@ bool Certificate::Save(FileUtil::IOFile& file) const {
     return true;
 }
 
+std::pair<CryptoPP::Integer, CryptoPP::Integer> Certificate::GetRSAPublicKey() const {
+    if (body.key_type == PublicKeyType::RSA_2048) {
+        return {CryptoPP::Integer(public_key.data(), 0x100),
+                CryptoPP::Integer(public_key.data() + 0x100, 0x4)};
+    } else if (body.key_type == PublicKeyType::RSA_4096) {
+        return {CryptoPP::Integer(public_key.data(), 0x200),
+                CryptoPP::Integer(public_key.data() + 0x200, 0x4)};
+    } else {
+        UNREACHABLE_MSG("Certificate is not RSA");
+    }
+}
+
 namespace Certs {
 
 static std::unordered_map<std::string, Certificate> g_certs;
@@ -131,9 +144,12 @@ bool Load(const std::string& path) {
             return false;
         }
 
+        const auto issuer = Common::StringFromFixedZeroTerminatedBuffer(cert.body.issuer.data(),
+                                                                        cert.body.issuer.size());
         const auto name = Common::StringFromFixedZeroTerminatedBuffer(cert.body.name.data(),
                                                                       cert.body.name.size());
-        g_certs.emplace(name, std::move(cert));
+        const auto full_name = issuer + "-" + name;
+        g_certs.emplace(full_name, std::move(cert));
 
         pos += size;
     }
@@ -157,6 +173,10 @@ const Certificate& Get(const std::string& name) {
     return g_certs.at(name);
 }
 
+bool Exists(const std::string& name) {
+    return g_certs.count(name);
+}
+
 } // namespace Certs
 
 } // namespace Core

src/core/ncch/certificate.h

@@ -10,6 +10,10 @@
 #include "common/common_funcs.h"
 #include "common/swap.h"
 
+namespace CryptoPP {
+class Integer;
+}
+
 namespace FileUtil {
 class IOFile;
 }
@@ -36,6 +40,9 @@ public:
     std::size_t Load(std::vector<u8> file_data, std::size_t offset = 0);
     bool Save(FileUtil::IOFile& file) const;
 
+    /// (modulus, exponent)
+    std::pair<CryptoPP::Integer, CryptoPP::Integer> GetRSAPublicKey() const;
+
     u32_be signature_type;
     std::vector<u8> signature;
     Body body;
@@ -55,6 +62,7 @@ namespace Certs {
 bool Load(const std::string& path);
 bool IsLoaded();
 const Certificate& Get(const std::string& name);
+bool Exists(const std::string& name);
 
 } // namespace Certs
 

src/core/ncch/cia_common.h

@@ -37,10 +37,11 @@ inline u32 GetSignatureSize(u32 signature_type) {
     return 0;
 }
 
+/// Full names of the certificates contained in a CIA.
 constexpr std::array<const char*, 3> CIACertNames{{
-    "CA00000003",
+    "Root-CA00000003",
-    "XS0000000c",
+    "Root-CA00000003-XS0000000c",
-    "CP0000000b",
+    "Root-CA00000003-CP0000000b",
 }};
 
 } // namespace Core

src/core/ncch/title_metadata.cpp

@@ -4,11 +4,14 @@
 
 #include <algorithm>
 #include <cinttypes>
+#include <cryptopp/rsa.h>
 #include <cryptopp/sha.h>
 #include "common/alignment.h"
 #include "common/assert.h"
 #include "common/file_util.h"
 #include "common/logging/log.h"
+#include "common/string_util.h"
+#include "core/ncch/certificate.h"
 #include "core/ncch/cia_common.h"
 #include "core/ncch/title_metadata.h"
 
@@ -120,6 +123,39 @@ ResultStatus TitleMetadata::Save(const std::string& file_path) {
     return Save(file);
 }
 
+bool TitleMetadata::ValidateSignature() const {
+    if (!Certs::IsLoaded()) {
+        LOG_ERROR(Core, "Certificates not available");
+        return false;
+    }
+
+    const auto cert_name =
+        Common::StringFromFixedZeroTerminatedBuffer(tmd_body.issuer.data(), tmd_body.issuer.size());
+    if (!Certs::Exists(cert_name)) {
+        LOG_ERROR(Core, "Cert {} does not exist", cert_name);
+        return false;
+    }
+
+    const auto& cert = Certs::Get(cert_name);
+    if (signature_type != TMDSignatureType::Rsa2048Sha256 ||
+        cert.body.key_type != PublicKeyType::RSA_2048) {
+
+        LOG_ERROR(Core, "Unsupported TMD signature type or cert public key type");
+        return false;
+    }
+
+    const auto [modulus, exponent] = Certs::Get(cert_name).GetRSAPublicKey();
+    CryptoPP::RSASS<CryptoPP::PKCS1v15, CryptoPP::SHA256>::Verifier verifier(modulus, exponent);
+
+    auto* message = verifier.NewVerificationAccumulator();
+    message->Update(reinterpret_cast<const u8*>(&tmd_body), sizeof(tmd_body));
+    message->Update(reinterpret_cast<const u8*>(tmd_chunks.data()),
+                    tmd_chunks.size() * sizeof(ContentChunk));
+    verifier.InputSignature(*message, tmd_signature.data(), tmd_signature.size());
+
+    return verifier.Verify(message);
+}
+
 std::size_t TitleMetadata::GetSize() const {
     const std::size_t body_start =
         Common::AlignUp(GetSignatureSize(signature_type) + sizeof(u32), 0x40);

src/core/ncch/title_metadata.h

@@ -51,7 +51,7 @@ public:
 #pragma pack(push, 1)
 
     struct Body {
-        std::array<u8, 0x40> issuer;
+        std::array<char, 0x40> issuer;
         u8 version;
         u8 ca_crl_version;
         u8 signer_crl_version;
@@ -82,8 +82,9 @@ public:
     ResultStatus Save(FileUtil::IOFile& file);
     ResultStatus Save(const std::string& file_path);
 
-    std::size_t GetSize() const;
+    bool ValidateSignature() const;
 
+    std::size_t GetSize() const;
     u64 GetTitleID() const;
     u32 GetTitleType() const;
     u16 GetTitleVersion() const;