Source release 17.1.2

oemcrypto/util/src/oemcrypto_key_deriver.cpp

@@ -40,6 +40,31 @@ bool Derive256Key(Cmac* cmac, uint8_t counter_base, const uint8_t* ctx,
   }
   return Derive128KeyAppend(cmac, counter_base + 1, ctx, ctx_size, derived_key);
 }
+
+bool NistKdf(Cmac* cmac, const std::vector<uint8_t>& label,
+             const std::vector<uint8_t>& context, size_t bits,
+             std::vector<uint8_t>* renewed_device_key) {
+  const std::vector<uint8_t> size_bits_big_endian = {
+      static_cast<uint8_t>(bits >> 24), static_cast<uint8_t>(bits >> 16),
+      static_cast<uint8_t>(bits >> 8), static_cast<uint8_t>(bits)};
+  const size_t kAesBlockSizeBits = 16 * 8;
+
+  if (bits % kAesBlockSizeBits != 0) return false;
+  if (renewed_device_key == nullptr) {
+    return false;
+  }
+  renewed_device_key->clear();
+  bool res = false;
+  for (size_t counter = 0; counter < bits / kAesBlockSizeBits; counter++) {
+    cmac->Reset();
+    res = cmac->Update(counter + 1) && cmac->Update(label) &&
+          cmac->Update(0x00) && cmac->Update(context) &&
+          cmac->Update(size_bits_big_endian) &&
+          cmac->FinalizeAppend(renewed_device_key);
+    if (!res) break;
+  }
+  return res;
+}
 }  // namespace
 
 // static
@@ -150,5 +175,20 @@ bool KeyDeriver::DeriveEncryptionKey(
   return DeriveEncryptionKey(enc_key_context.data(), enc_key_context.size(),
                              enc_key);
 }
+
+bool KeyDeriver::DeriveRenewedDeviceKey(
+    const std::vector<uint8_t>& context,
+    std::vector<uint8_t>* renewed_device_key) {
+  if (renewed_device_key == nullptr) {
+    LOGE("Output key buffer is null");
+    return false;
+  }
+  const std::string kKeyboxRenewalLabel = "Keyboxv4";
+  const std::vector<uint8_t> kKeyboxRenewalLabelVec(kKeyboxRenewalLabel.begin(),
+                                                    kKeyboxRenewalLabel.end());
+
+  return NistKdf(cmac_.get(), kKeyboxRenewalLabelVec, context, 0x80,
+                 renewed_device_key);
+}
 }  // namespace util
 }  // namespace wvoec

oemcrypto/util/src/oemcrypto_rsa_key.cpp

@@ -326,6 +326,27 @@ bool RsaPublicKey::IsMatchingPrivateKey(
   return RsaKeysAreMatchingPair(GetRsaKey(), private_key.GetRsaKey());
 }
 
+std::vector<uint8_t> RsaPrivateKey::GetPrivateExponent() const {
+  const BIGNUM* d = RSA_get0_d(key_);
+  if (d == nullptr) {
+    LOGE("Private exponent must not be null");
+    return {};
+  }
+  // Get the required length for the data.
+  const size_t length = BN_num_bytes(d);
+  if (length <= 0) {
+    LOGE("Private exponent length must be positive");
+    return {};
+  }
+  std::vector<uint8_t> serialized_private_exponent(length, 0);
+  if (static_cast<size_t>(BN_bn2bin(d, serialized_private_exponent.data())) !=
+      length) {
+    LOGE("Failed to convert the private exponent");
+    return {};
+  }
+  return serialized_private_exponent;
+}
+
 OEMCryptoResult RsaPublicKey::Serialize(uint8_t* buffer,
                                         size_t* buffer_size) const {
   if (buffer_size == nullptr) {