text: #ifndef _SIGNATURESERVICE_H_
  #define _SIGNATURESERVICE_H_
  
  #include <openssl/evp.h>
  
  #include "../model/Document.h"
  #include "../model/Key.h"
  
  class SignatureService
  {
  private:
  
  public:
    SignatureService();
    bool validate(Document* document);
    char* sign(char* document, Key *key);
    EVP_PKEY* getPrivateKeyOpenSSL(char *key);
  };
  
  #endif