text: /*
   * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License").
   * You may not use this file except in compliance with the License.
   * A copy of the License is located at
   *
   *  http://aws.amazon.com/apache2.0
   *
   * or in the "license" file accompanying this file. This file is distributed
   * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
   * express or implied. See the License for the specific language governing
   * permissions and limitations under the License.
   */
  
  #include <s2n.h>
  
  #include "error/s2n_errno.h"
  
  #include "tls/s2n_connection.h"
  #include "tls/s2n_config.h"
  #include "tls/s2n_signature_algorithms.h"
  #include "tls/s2n_tls.h"
  
  #include "stuffer/s2n_stuffer.h"
  
  #include "utils/s2n_safety.h"
  
  
  int s2n_client_cert_verify_recv(struct s2n_connection *conn)
  {
      struct s2n_stuffer *in = &conn->handshake.io;
      struct s2n_signature_scheme chosen_sig_scheme = s2n_rsa_pkcs1_md5_sha1;
  
      if(conn->actual_protocol_version == S2N_TLS12){
          /* Verify the Server picked one of the SignatureSchemes that we sent in the ClientCertificateRequest */
          GUARD(s2n_get_and_validate_negotiated_signature_scheme(conn, in, &chosen_sig_scheme));
      }
      uint16_t signature_size;
      struct s2n_blob signature = {0};
      GUARD(s2n_stuffer_read_uint16(in, &signature_size));
      signature.size = signature_size;
      signature.data = s2n_stuffer_raw_read(in, signature.size);
      notnull_check(signature.data);
  
      /* Use a copy of the hash state since the verify digest computation may modify the running hash state we need later. */
      struct s2n_hash_state hash_state = {0};
      GUARD(s2n_handshake_get_hash_state(conn, chosen_sig_scheme.hash_alg, &hash_state));
      GUARD(s2n_hash_copy(&conn->handshake.ccv_hash_copy, &hash_state));
  
      /* Verify the signature */
      GUARD(s2n_pkey_verify(&conn->secure.client_public_key, chosen_sig_scheme.sig_alg, &conn->handshake.ccv_hash_copy, &signature));
  
      /* Client certificate has been verified. Minimize required handshake hash algs */
      GUARD(s2n_conn_update_required_handshake_hashes(conn));
  
      return 0;
  }
  
  
  int s2n_client_cert_verify_send(struct s2n_connection *conn)
  {
      struct s2n_stuffer *out = &conn->handshake.io;
  
      struct s2n_signature_scheme chosen_sig_scheme = s2n_rsa_pkcs1_md5_sha1;
  
      if(conn->actual_protocol_version == S2N_TLS12){
          chosen_sig_scheme =  conn->secure.client_cert_sig_scheme;
          GUARD(s2n_stuffer_write_uint16(out, conn->secure.client_cert_sig_scheme.iana_value));
      }
  
      /* Use a copy of the hash state since the verify digest computation may modify the running hash state we need later. */
      struct s2n_hash_state hash_state = {0};
      GUARD(s2n_handshake_get_hash_state(conn, chosen_sig_scheme.hash_alg, &hash_state));
      GUARD(s2n_hash_copy(&conn->handshake.ccv_hash_copy, &hash_state));
  
      struct s2n_cert_chain_and_key *cert_chain_and_key = conn->handshake_params.our_chain_and_key;
      struct s2n_blob signature = {0};
      signature.size = s2n_pkey_size(cert_chain_and_key->private_key);
      GUARD(s2n_stuffer_write_uint16(out, signature.size));
      signature.data = s2n_stuffer_raw_write(out, signature.size);
      notnull_check(signature.data);
  
      GUARD(s2n_pkey_sign(cert_chain_and_key->private_key, chosen_sig_scheme.sig_alg, &conn->handshake.ccv_hash_copy, &signature));
  
      /* Client certificate has been verified. Minimize required handshake hash algs */
      GUARD(s2n_conn_update_required_handshake_hashes(conn));
  
      return 0;
  }
  