1 files changed, 80 insertions, 0 deletions
diff --git a/store/works/life/information-security-experiment/des.cpp b/store/works/life/information-security-experiment/des.cpp
new file mode 100644
index 0000000..93a6ea3
--- /dev/null
+++ b/store/works/life/information-security-experiment/des.cpp
@@ -0,0 +1,80 @@
+#include <openssl/des.h>
+#include <openssl/evp.h>
+
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+
+void PrintCblock(const DES_cblock &b, bool end_line = true) {
+  std::cout << std::hex << std::right << std::setfill('0');
+
+  for (auto c : b) {
+    std::cout << std::setw(2) << static_cast<int>(c);
+  }
+
+  if (end_line) {
+    std::cout << std::endl;
+  }
+}
+
+int main() {
+  auto cipher = EVP_des_cfb();
+
+  std::cout << "Selected cipher: des_cfb" << std::endl;
+
+  auto key_length = EVP_CIPHER_key_length(cipher);
+  std::cout << "Key length: " << key_length << std::endl;
+
+  auto iv_length = EVP_CIPHER_iv_length(cipher);
+  std::cout << "IV length: " << iv_length << std::endl;
+
+  auto block_length = EVP_CIPHER_block_size(cipher);
+  std::cout << "Block length: " << block_length << std::endl;
+
+  DES_cblock key;
+
+  std::srand(std::time(nullptr));
+
+  std::cout << std::hex << std::setfill('0');
+
+  if (DES_random_key(&key) == 0) {
+    std::cerr << "Failed to generate key." << std::endl;
+    return 1;
+  } else {
+    std::cout << "Succeeded to generate key." << std::endl;
+    std::cout << "Key: ";
+    PrintCblock(key);
+  }
+
+  DES_key_schedule key_schedule;
+
+  {
+    auto result = DES_set_key_checked(&key, &key_schedule);
+
+    if (result == -1) {
+      std::cerr << "Parity is wrong." << std::endl;
+      return 1;
+    } else if (result == -2) {
+      std::cerr << "Key is too weak." << std::endl;
+    }
+  }
+
+  DES_cblock clear_text = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
+
+  std::cout << "Clear text: " << std::hex;
+  PrintCblock(clear_text);
+
+  DES_cblock cipher_text;
+
+  DES_ecb_encrypt(&clear_text, &cipher_text, &key_schedule, 1);
+
+  std::cout << "Cipher text after encrypted: " << std::hex;
+  PrintCblock(cipher_text);
+
+  DES_ecb_encrypt(&cipher_text, &clear_text, &key_schedule, 0);
+
+  std::cout << "Clear text after decrypted: " << std::hex;
+  PrintCblock(clear_text);
+
+  return 0;
+}