decrypt.c

Example use of encrypted files, protected with password or certificate.

#include "tools.h"
 
void print_decrypt_help() {
    printf("Usage: decrypt -s [source file] -p [password] -k [path to PKCS#12]");
}
 
int process_decrypt(int argc, char *argv[]) {
    FileHandle* file = NULL;
    string_type password = NULL;
    string_type cert_path = NULL;
    string_type file_path = NULL;
 
    integer_type i = 0;
 
    for (i = 0; i < argc; ++i) {
 
        // password
        if (strcmp(argv[i], "-p") == 0 && (i + 1 < argc)) {
            password = argv[i + 1];
            i++;
 
            // certificate
        } else if (strcmp(argv[i], "-k") == 0 && (i + 1 < argc)) {
            cert_path = argv[i + 1];
            i++;
            // source file path
        } else if (strcmp(argv[i], "-s") == 0 && (i + 1 < argc)) {
            file_path = argv[i + 1];
            i++;
        } else {
            print_decrypt_help();
            return VANILLAPDF_TOOLS_ERROR_INVALID_PARAMETERS;
        }
    }
 
    if (file_path == NULL) {
        print_decrypt_help();
        return VANILLAPDF_TOOLS_ERROR_INVALID_PARAMETERS;
    }
 
    RETURN_ERROR_IF_NOT_SUCCESS(File_Open(file_path, &file));
 
    if (password != NULL) {
        RETURN_ERROR_IF_NOT_SUCCESS(File_SetEncryptionPassword(file, password));
    }
 
    if (cert_path != NULL) {
        PKCS12KeyHandle* pkcs12_key = NULL;
        EncryptionKeyHandle* encryption_key = NULL;
        RETURN_ERROR_IF_NOT_SUCCESS(PKCS12Key_CreateFromFile(cert_path, NULL, &pkcs12_key));
        RETURN_ERROR_IF_NOT_SUCCESS(PKCS12Key_ToEncryptionKey(pkcs12_key, &encryption_key));
        RETURN_ERROR_IF_NOT_SUCCESS(File_SetEncryptionKey(file, encryption_key));
 
        RETURN_ERROR_IF_NOT_SUCCESS(EncryptionKey_Release(encryption_key));
        RETURN_ERROR_IF_NOT_SUCCESS(PKCS12Key_Release(pkcs12_key));
    }
 
    // File contents are now accessible
 
    RETURN_ERROR_IF_NOT_SUCCESS(File_Release(file));
    return VANILLAPDF_TOOLS_ERROR_SUCCESS;
}