Ensure that test BCC are unique per call am: 3c44456c54

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/keymaster/+/15192383

Change-Id: I4af3f6d4b2c3f3cea06110a7dc06bfe19b8f1b1c

4 files changed, 12 insertions, 7 deletions

diff --git a/android_keymaster/android_keymaster.cpp b/android_keymaster/android_keymaster.cpp
index ab3b9d1..3850481 100644
--- a/android_keymaster/android_keymaster.cpp
+++ b/android_keymaster/android_keymaster.cpp
@@ -421,7 +421,7 @@ void AndroidKeymaster::GenerateCsr(const GenerateCsrRequest& request,
     std::vector<uint8_t> devicePrivKey;
     cppbor::Array bcc;
     if (request.test_mode) {
-        std::tie(devicePrivKey, bcc) = rem_prov_ctx->GenerateBcc();
+        std::tie(devicePrivKey, bcc) = rem_prov_ctx->GenerateBcc(/*testMode=*/true);
     } else {
         devicePrivKey = rem_prov_ctx->devicePrivKey_;
         auto clone = rem_prov_ctx->bcc_.clone();
diff --git a/contexts/pure_soft_remote_provisioning_context.cpp b/contexts/pure_soft_remote_provisioning_context.cpp
index e79a856..a943f42 100644
--- a/contexts/pure_soft_remote_provisioning_context.cpp
+++ b/contexts/pure_soft_remote_provisioning_context.cpp
@@ -25,6 +25,7 @@
 #include <openssl/bn.h>
 #include <openssl/ec.h>
 #include <openssl/hkdf.h>
+#include <openssl/rand.h>
 
 namespace keymaster {
 
@@ -38,7 +39,7 @@ using cppcose::VERIFY;
 constexpr uint32_t kMacKeyLength = 32;
 
 PureSoftRemoteProvisioningContext::PureSoftRemoteProvisioningContext() {
-    std::tie(devicePrivKey_, bcc_) = GenerateBcc();
+    std::tie(devicePrivKey_, bcc_) = GenerateBcc(/*testMode=*/false);
 }
 
 PureSoftRemoteProvisioningContext::~PureSoftRemoteProvisioningContext() {}
@@ -84,13 +85,17 @@ std::unique_ptr<cppbor::Map> PureSoftRemoteProvisioningContext::CreateDeviceInfo
 }
 
 std::pair<std::vector<uint8_t> /* privKey */, cppbor::Array /* BCC */>
-PureSoftRemoteProvisioningContext::GenerateBcc() const {
+PureSoftRemoteProvisioningContext::GenerateBcc(bool testMode) const {
     std::vector<uint8_t> privKey(ED25519_PRIVATE_KEY_LEN);
     std::vector<uint8_t> pubKey(ED25519_PUBLIC_KEY_LEN);
 
     uint8_t seed[32];  // Length is hard-coded in the BoringCrypto API
-    auto seed_vector = DeriveBytesFromHbk("Device Key Seed", sizeof(seed));
-    std::copy(seed_vector.begin(), seed_vector.end(), seed);
+    if (testMode) {
+        RAND_bytes(seed, sizeof(seed));
+    } else {
+        auto seed_vector = DeriveBytesFromHbk("Device Key Seed", sizeof(seed));
+        std::copy(seed_vector.begin(), seed_vector.end(), seed);
+    }
     ED25519_keypair_from_seed(pubKey.data(), privKey.data(), seed);
 
     auto coseKey = cppbor::Map()
diff --git a/include/keymaster/contexts/pure_soft_remote_provisioning_context.h b/include/keymaster/contexts/pure_soft_remote_provisioning_context.h
index 98baa0a..307795b 100644
--- a/include/keymaster/contexts/pure_soft_remote_provisioning_context.h
+++ b/include/keymaster/contexts/pure_soft_remote_provisioning_context.h
@@ -32,7 +32,7 @@ class PureSoftRemoteProvisioningContext : public RemoteProvisioningContext {
     std::vector<uint8_t> DeriveBytesFromHbk(const std::string& context,
                                             size_t numBytes) const override;
     std::unique_ptr<cppbor::Map> CreateDeviceInfo() const override;
-    std::pair<std::vector<uint8_t>, cppbor::Array> GenerateBcc() const override;
+    std::pair<std::vector<uint8_t>, cppbor::Array> GenerateBcc(bool testMode) const override;
     std::optional<cppcose::HmacSha256>
     GenerateHmacSha256(const cppcose::bytevec& input) const override;
 };
diff --git a/include/keymaster/remote_provisioning_context.h b/include/keymaster/remote_provisioning_context.h
index 656a1e6..a5c4d1d 100644
--- a/include/keymaster/remote_provisioning_context.h
+++ b/include/keymaster/remote_provisioning_context.h
@@ -34,7 +34,7 @@ class RemoteProvisioningContext {
     virtual std::vector<uint8_t> DeriveBytesFromHbk(const std::string& context,
                                                     size_t numBytes) const = 0;
     virtual std::unique_ptr<cppbor::Map> CreateDeviceInfo() const = 0;
-    virtual std::pair<std::vector<uint8_t>, cppbor::Array> GenerateBcc() const = 0;
+    virtual std::pair<std::vector<uint8_t>, cppbor::Array> GenerateBcc(bool testMode) const = 0;
 
     // Generate an HMAC-SHA256 over the given input. This is used to verify a given
     // input hasn't changed across multiple calls to the remote provisioning HAL.