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// question 1: When should I call the create_mitigator_header_H function? It can be called as early as verify_peer_enclave_trust. Or as late as when encrypt_mitigator_header_H_to_apache is called. But then you need to make sure that successful_la_count is right for that.
// question 2: nightmare about the process_message_generate_response function.

#include "Decryptor.h"
#include "sgx_tseal.h"
#include "sgx_tcrypto.h"
#include "sgx_dh.h"
#include "datatypes.h"
#include "error_codes.h"


        ECDSASignatureBox Decryptor::signatureBox;
        HybridEncryptionBox Decryptor::hybridEncryptionBoxClient;
        SymmetricEncryptionBox Decryptor::symmetricEncryptionBoxApache;
        SymmetricEncryptionBox Decryptor::symmetricEncryptionBoxVerifier;
        uint8_t Decryptor::verifier_mr_enclave[32] = {0};
        uint8_t Decryptor::apache_mr_signer[32] = {0};
        unsigned int successful_la_count;
        uint8_t Decryptor::plaintext_mitigator_header_H[ECDH_PUBLIC_KEY_SIZE + 32 + 64]={0};


  // INTERNAL
  uint32_t Decryptor::create_mitigator_token_M(uint8_t* token)
  {
    uint32_t internal_return_status;
    uint32_t counter;
    // create short-term ECDH key pair
    internal_return_status = hybridEncryptionBoxClient.generate_keypair();
    if(internal_return_status == NULL)
      return 0xff;
    hybridEncryptionBoxClient.get_public_key(token);

    // create token: concatenate short-term keypair with verifiers mrenclave.
    for(counter=0;counter<32;counter++)
      *(token + counter + ECDH_PUBLIC_KEY_SIZE) = verifier_mr_enclave[counter];

    return 0;
  }

  // INTERNAL
  uint32_t Decryptor::create_mitigator_header_H(uint8_t* signature_data_and_signature)
  {
    uint32_t internal_return_status;
    uint8_t local_signature_data_and_signature[ECDH_PUBLIC_KEY_SIZE + 32 + 64];
    uint32_t counter;
    internal_return_status = Decryptor::create_mitigator_token_M(local_signature_data_and_signature);
    if(internal_return_status != 0x0)
      return internal_return_status;

    internal_return_status = signatureBox.sign(local_signature_data_and_signature, ECDH_PUBLIC_KEY_SIZE + 32, local_signature_and_signature + ECDH_PUBLIC_KEY_SIZE + 32);
    if(internal_return_status != 0x0)
      return internal_return_status;
    for(counter=0;counter<ECDH_PUBLIC_KEY_SIZE + 32 + 64;counter++)
      signature_data_and_signature[counter] = local_signature_data_and_signature[counter];
    return 0;
  }

  // EXTERNAL ECALL.
  uint32_t Decryptor::encrypt_mitigator_header_H_to_apache(uint8_t* ciphertext_token_H_plus_tag)
  {
    	uint32_t counter;
    	uint8_t sign_data_and_sign[ECDH_PUBLIC_KEY_SIZE + 32 + 64 + 10];
      uint8_t temp_tag[16];
      uint32_t temp_ciphertext_token_H_length;
    	uint32_t internal_return_status;

      if(successful_la_count != 2)
        return 0x33;

      internal_return_status = create_mitigator_header_H(plaintext_mitigator_header_H);
      if(internal_return_status != 0)
        return internal_return_status;

      internal_return_status = symmetricEncryptionBoxApache.encrypt_decrypt(1, plaintext_mitigator_header_H, ECDH_PUBLIC_KEY_SIZE + 32 + 64, ciphertext_token_H_plus_tag, &temp_ciphertext_token_H_length);
      if(internal_return_status != 0)
        return internal_return_status;

      if(temp_ciphertext_token_H_length != 160)
        return 0x45;
    	return 0;
    }

  // INTERNAL. done. But there might be one more return statement for the case when get_keypair returns sth (it is non void).
  uint32_t Decryptor::create_long_term_signing_keypair(uint8_t* private_public_key_string)
  {
    uint32_t internal_return_status;
    internal_return_status = signatureBox.generate_keypair();
    if(internal_return_status != 0)
      return internal_return_status;

    signatureBox.get_keypair(private_public_key_string);
    return 0;
  }

  // INTERNAL.
  uint32_t Decryptor::initialize_symmetric_key_decrypt_client_data(uint8_t* plaintext_client_public_key_plus_encrypted_data_plus_tag, uint32_t total_length, uint8_t* plaintext_client_data, uint32_t* plaintext_client_data_length)
  {
    uint8_t* ciphertext;
    uint32_t ciphertext_length;
    uint32_t internal_return_status;
    // and now I will derive a shared key from the plaintext_client_public_key
    internal_return_status = hybridEncryptionBoxClient.initialize_symmetric_key(plaintext_client_public_key_plus_encrypted_data_plus_tag);
    if(internal_return_status != 0)
      return internal_return_status;

    // and then I will decrypt the rest of the client data with that key.
    ciphertext = plaintext_client_public_key_plus_encrypted_data_plus_tag + ECDH_PUBLIC_KEY_SIZE;
    ciphertext_length = total_length - ECDH_PUBLIC_KEY_SIZE - 16;

    internal_return_status = hybridEncryptionBoxClient.encrypt_decrypt(0, ciphertext, ciphertext_length, plaintext_client_data, plaintext_client_data_length);
    return internal_return_status;
  }

  // EXTERNAL. DONE.
  uint32_t Decryptor::create_and_seal_long_term_signing_key_pair(uint32_t* sealed_data_length, uint8_t* sealed_data)
  {
        uint32_t sgx_libcall_status;
        uint32_t internal_return_status;
        uint32_t temp_sealed_data_length;
        uint8_t* temp_sealed_data;
        uint8_t private_public_key_string[ECDH_PUBLIC_KEY_SIZE + ECDH_PRIVATE_KEY_SIZE];
        uint32_t counter;

        temp_sealed_data_length = sgx_calc_sealed_data_size(0, ECDH_PUBLIC_KEY_SIZE + ECDH_PRIVATE_KEY_SIZE);
        if(temp_sealed_data_length == 0xFFFFFFFF)
          return 0x01;


        temp_sealed_data = (uint8_t*) malloc(temp_sealed_data_length);

        internal_return_status = create_long_term_signing_keypair(private_public_key_string);
      	if(internal_return_status != 0)
      	{
      		free(temp_sealed_data);
      		return internal_return_status;
      	}

        sgx_libcall_status = sgx_seal_data(0, NULL, 3*SGX_ECP256_KEY_SIZE, private_public_key_string, temp_sealed_data_length, (sgx_sealed_data_t*) temp_sealed_data);
        if(sgx_libcall_status != SGX_SUCCESS)
        {
          free(temp_sealed_data);
          return sgx_libcall_status;
        }

        for(counter=0;counter<temp_sealed_data_length;counter++)
    			*(sealed_data + counter)= *(temp_sealed_data + counter);
	      *sealed_data_length = temp_sealed_data_length;
        free(temp_sealed_data);

        return 0;
    }

  // EXTERNAL. DONE.
  uint32_t Decryptor::unseal_and_restore_long_term_signing_key_pair(uint8_t* sealed_data, uint32_t* sgx_sealed_data_length)
  {
      uint32_t temp_plaintext_length;
      uint8_t* temp_plaintext;
      uint32_t counter;
      uint32_t ret_status;
      uint8_t* temp_sealed_data ;

      temp_sealed_data = (uint8_t*) malloc(*sgx_sealed_data_length);
      for(counter=0;counter<*sgx_sealed_data_length;counter++)
        *(temp_sealed_data+counter)=*(sealed_data+counter);

      temp_plaintext_length = sgx_get_encrypt_txt_len((sgx_sealed_data_t*)sealed_data);
      if(temp_plaintext_length == 0xffffffff)
        return 0xFFFFFFFF;
      temp_plaintext = (uint8_t*)malloc( temp_plaintext_length );

      ret_status = sgx_unseal_data((sgx_sealed_data_t*)temp_sealed_data, NULL, 0, temp_plaintext, &temp_plaintext_length);
      free(temp_sealed_data);
      if(ret_status != SGX_SUCCESS)
      {
        free(temp_plaintext);
        return ret_status;
      }

      signatureBox.set_private_public_key(temp_plaintext, temp_plaintext + ECDH_PRIVATE_KEY_SIZE);
      free(temp_plaintext);
      return 0;
    }

  uint32_t Decryptor::process_verifiers_message(uint8_t* input_ciphertext, uint32_t input_ciphertext_plus_tag_length)
  {
        uint8_t *first_decryption_output, *plaintext_client_data, *temp_output_ciphertext;
        uint32_t first_decryption_output_length, plaintext_client_data_length;
        uint32_t temp_output_ciphertext_length, internal_return_status;
        uint8_t temp_output_tag[16]; uint32_t counter;
        if(successful_la_count != 1) // else, the untrusted application can call this on the first message by apache and cause the verifier to set its mrsigner.
          return 0x23;
        // TODO: May be have temporary variables for input ciphertext as they can't be passed directly to functions?
        first_decryption_output = (uint8_t*) malloc(input_ciphertext_plus_tag_length);
        internal_return_status = symmetricEncryptionBoxVerifier.encrypt_decrypt(0, input_ciphertext, input_ciphertext_plus_tag_length - 16, first_decryption_output, &first_decryption_output_length);
        if(internal_return_status != 0)
        {
          free(first_decryption_output);
          return internal_return_status;
        }

        if(first_decryption_output_length != 32)
        {
          free(first_decryption_output);
          return 0x33;
        }
        for(counter=0; counter<32; counter++)
        {
          apache_mr_signer[counter] = *(first_decryption_output + counter);
        }
        free(first_decryption_output);
        return 0;
  }

  // EXTERNAL. DONE.
  uint32_t Decryptor::process_apache_message_generate_response(uint8_t* input_ciphertext, uint32_t input_ciphertext_plus_tag_length, uint8_t* output_ciphertext_plus_tag, uint32_t* output_ciphertext_plus_tag_length)
  {
      uint8_t *first_decryption_output, *plaintext_client_data;
      uint32_t first_decryption_output_length, plaintext_client_data_length;
      uint32_t internal_return_status;
      // TODO: May be have temporary variables for input ciphertext as they can't be passed directly to functions?
      first_decryption_output = (uint8_t*) malloc(input_ciphertext_plus_tag_length);
      internal_return_status = symmetricEncryptionBoxApache.encrypt_decrypt(0, input_ciphertext, input_ciphertext_plus_tag_length - 16, first_decryption_output, &first_decryption_output_length);
      if(internal_return_status != 0)
      {
        free(first_decryption_output);
        return internal_return_status;
      }

      plaintext_client_data = (uint8_t*) malloc(first_decryption_output_length); // you will need less than this coz public key size.
      internal_return_status = initialize_symmetric_key_decrypt_client_data(first_decryption_output, first_decryption_output_length, plaintext_client_data, &plaintext_client_data_length);
      free(first_decryption_output);
      if(internal_return_status != 0)
        return internal_return_status;

      // then I will encrypt the resulting first_decryption_output to the apache enclave.
      internal_return_status = symmetricEncryptionBoxApache.encrypt_decrypt(1, plaintext_client_data, plaintext_client_data_length, output_ciphertext_plus_tag, output_ciphertext_plus_tag_length);
      free(plaintext_client_data);
      if(internal_return_status != 0)
        return internal_return_status;
      return 0;
    }

  // INTERNAL.
  uint32_t Decryptor::verify_peer_enclave_trust(uint8_t* given_mr_enclave, uint8_t* given_mr_signer, uint8_t* dhaek)
  {
        uint32_t count;
        uint32_t internal_return_status;
        if(successful_la_count == 0) // verifier enclave
        {
                for(count=0; count<SGX_HASH_SIZE; count++)
                        verifier_mr_enclave[count] = given_mr_enclave[count];
		            symmetricEncryptionBoxVerifier.set_symmetric_key(dhaek);
        }
        else // apache enclave
        {
                for(count=0; count<SGX_HASH_SIZE; count++)
                {
                        if( given_mr_signer[count] != apache_mr_signer[count] )
                                return ENCLAVE_TRUST_ERROR;
                }
		            symmetricEncryptionBoxApache.set_symmetric_key(dhaek);
        }
        successful_la_count ++;
        return SGX_SUCCESS;
  }

  void Decryptor::calculate_sealed_keypair_size(uint32_t* output_length)
  {
	*output_length = sgx_calc_sealed_data_size(0, ECDH_PUBLIC_KEY_SIZE + ECDH_PRIVATE_KEY_SIZE);
}