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Asked: 2026-05-10T15:17:45+00:00

I have a legacy C++ module that offers encryption/decryption using the openssl library (DES

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I have a legacy C++ module that offers encryption/decryption using the openssl library (DES encryption). I’m trying to translate that code into java, and I don’t want to rely on a DLL, JNI, etc… C++ code looks like:

des_string_to_key(reinterpret_cast<const char *>(key1), &initkey); des_string_to_key(reinterpret_cast<const char *>(key2), &key); key_sched(&key, ks); // ... des_ncbc_encrypt(reinterpret_cast<const unsigned char *>(tmp.c_str()),  reinterpret_cast< unsigned char *>(encrypted_buffer), tmp.length(), ks, &initkey,  DES_ENCRYPT);  return base64(reinterpret_cast<const unsigned char *>(encrypted_buffer),    strlen(encrypted_buffer));

Java code looks like:

Cipher ecipher; try {     ecipher = Cipher.getInstance('DES');     SecretKeySpec keySpec = new SecretKeySpec(key, 'DES');           ecipher.init(Cipher.ENCRYPT_MODE, keySpec);              byte[] utf8 = password.getBytes('UTF8');     byte[] enc = ecipher.doFinal(utf8);     return new sun.misc.BASE64Encoder().encode(enc); } catch {     // ... }

So I can do DES encryption in Java pretty easily, but how can I get the same result as with the above code with methods that are completely different? What bothers me in particular is the fact that the C++ version uses 2 keys while the Java version uses only 1 key. The answer about DES in CBC mode is quite satisfying but I can’t get it to work yet. Here are more details about the original code: unsigned char key1[10]= {0}; unsigned char key2[50]= {0};

int i; for (i=0;i<8;i++)     key1[i] = 31+int((i*sqrt((double)i*5)))%100; key1[9]=0;  for (i=0;i<48;i++)     key2[i] = 31+int((i*i*sqrt((double)i*2)))%100; key2[49]=0; ... // Initialize encrypted buffer memset(encrypted_buffer, 0, sizeof(encrypted_buffer));  // Add begin Text and End Text to the encrypted message std::string input; const char beginText = 2; const char endText = 3; input.append(1,beginText); input.append(bufferToEncrypt); input.append(1,endText);      // Add padding tmp.assign(desPad(input));  des_ncbc_encrypt(reinterpret_cast<const unsigned char *>(tmp.c_str()),      reinterpret_cast< unsigned char *>(encrypted_buffer), tmp.length(), ks, &initkey,  DES_ENCRYPT); ...

From what I’ve read, the key should be 56 (or 64, it’s not clear to me) bits long, but here it’s 48 bytes long.

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1 Answer

  1. I’m not an OpenSSL expert, but I’d guess the C++ code is using DES in CBC mode thus needing an IV (that’s what the initKey probably is, and that’s why you think you need two keys). If I’m right, you need to change your Java code to use DES in CBC mode too, then the Java code too will require an encryption key and an IV.

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