hybrid_kem.cpp

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/**
* Abstraction for a combined KEM public and private key.
*
* (C) 2024 Jack Lloyd
*     2024 Fabian Albert, René Meusel - Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/hybrid_kem.h>
 
#include <botan/internal/concat_util.h>
#include <botan/internal/fmt.h>
#include <botan/internal/stl_util.h>
 
namespace Botan {
 
Hybrid_PublicKey::Hybrid_PublicKey(std::vector<std::unique_ptr<Public_Key>> pks) :
      m_pks(std::move(pks)), m_key_length(0), m_estimated_strength(0) {
   BOTAN_ARG_CHECK(m_pks.size() >= 2, "List of public keys must include at least two keys");
   for(const auto& pk : m_pks) {
      BOTAN_ARG_CHECK(pk != nullptr, "List of public keys contains a nullptr");
      BOTAN_ARG_CHECK(pk->supports_operation(PublicKeyOperation::KeyEncapsulation),
                      fmt("Public key type '{}' does not support key encapsulation", pk->algo_name()).c_str());
      m_key_length = std::max(m_key_length, pk->key_length());
      m_estimated_strength = std::max(m_estimated_strength, pk->estimated_strength());
   }
}
 
bool Hybrid_PublicKey::check_key(RandomNumberGenerator& rng, bool strong) const {
   return reduce(public_keys(), true, [&](bool ckr, const auto& key) { return ckr && key->check_key(rng, strong); });
}
 
std::vector<uint8_t> Hybrid_PublicKey::raw_public_key_bits() const {
   return reduce(public_keys(), std::vector<uint8_t>(), [](auto pkb, const auto& key) {
      return concat(pkb, key->raw_public_key_bits());
   });
}
 
bool Hybrid_PublicKey::supports_operation(PublicKeyOperation op) const {
   return PublicKeyOperation::KeyEncapsulation == op;
}
 
std::vector<std::unique_ptr<Private_Key>> Hybrid_PublicKey::generate_other_sks_from_pks(
   RandomNumberGenerator& rng) const {
   std::vector<std::unique_ptr<Private_Key>> new_private_keys;
   new_private_keys.reserve(public_keys().size());
   for(const auto& pk : public_keys()) {
      new_private_keys.push_back(pk->generate_another(rng));
   }
   return new_private_keys;
}
 
Hybrid_PrivateKey::Hybrid_PrivateKey(std::vector<std::unique_ptr<Private_Key>> private_keys) :
      m_sks(std::move(private_keys)) {
   BOTAN_ARG_CHECK(m_sks.size() >= 2, "List of secret keys must include at least two keys");
   for(const auto& sk : m_sks) {
      BOTAN_ARG_CHECK(sk != nullptr, "List of secret keys contains a nullptr");
      BOTAN_ARG_CHECK(sk->supports_operation(PublicKeyOperation::KeyEncapsulation),
                      "Some provided secret key is not compatible with this hybrid wrapper");
   }
}
 
secure_vector<uint8_t> Hybrid_PrivateKey::private_key_bits() const {
   throw Not_Implemented("Hybrid private keys cannot be serialized");
}
 
bool Hybrid_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const {
   return reduce(private_keys(), true, [&](bool ckr, const auto& key) { return ckr && key->check_key(rng, strong); });
}
 
std::vector<std::unique_ptr<Public_Key>> Hybrid_PrivateKey::extract_public_keys(
   const std::vector<std::unique_ptr<Private_Key>>& private_keys) {
   std::vector<std::unique_ptr<Public_Key>> public_keys;
   public_keys.reserve(private_keys.size());
   for(const auto& sk : private_keys) {
      BOTAN_ARG_CHECK(sk != nullptr, "List of private keys contains a nullptr");
      public_keys.push_back(sk->public_key());
   }
   return public_keys;
}
 
}  // namespace Botan