des

I'm in the need of decrypting with PHP (or Javascript) some service calls. I've spent all the day trying to accomplish, this, but I've been unable to decrypt it properly. As a reference, the service provider sent me the following decryption sample code in Java: DESKeySpec dks = new DESKeySpec("keyword".getBytes()); SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES"); SecretKey key = keyFactory.generateSecret(dks); Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding"); SecureRandom sr = new SecureRandom(); cipher.init( Cipher.DECRYPT_MODE, key ,sr); byte b[] = response

I'm having a bit of difficulty getting an understand of key length requirements in cryptography. I'm currently using DES which I believe is 56 bits... now, by converting an 8 character password to a byte[] my cryptography works. If I use a 7 digit password, it doesn't. Now, forgive me if I'm wrong, but is that because ASCII characters are 7 bits, therefor 8 * 7 = 56bits? That just doesn't seem right to me. If I want to use a key, why can I not just pass in a salted hash of my secret key, i.e. an MD5 hash? I'm sure this is very simple, but I can't get a clear understanding of what's going on.

Please note that the issue I am having here is with the key size . At first, based on the comments included in the below code, I figured that my key needed to be 24 bytes (192 bits). This didn't work so I gave 16, 32, and 8 byte keys a shot - nothing seems to be working. By "not working" I mean that after my text has been encrypted and decrypted it does not hold the same value as my original text. Example: Original Text: 'Example test this should work ' Encrypted Text: ¸ ¹pÕô6 Decrypted Text: 'Example ' Here are the two functions I am using (Encrypt / Decrypt functions). Also I will include

According to Wikipedia , TripleDES supports 56, 112, and 168-bit key lengths, but the System.Cryptography.TripleDESCryptoServiceProvider.LegalKeySizes says it only accepts 128 and 192-bit key lengths. The system I'm developing needs to be interoperable (data encrypted by my code needs to be decryptable in PHP, Java, and Objective-C) and I don't who is correct in this case. So who should I believe? And how can I be sure my encrypted data is portable? Wikipedia does not say TripleDES supports 56 bit keys. The "keying options" talk about "triple-length" keys and "double-length" keys, the latter

分组密码的基本概念 ​ 分组密码在加密过程中不是将明文按字符逐位加密，而是首先要将待加密的明文进行分组，每组的长度相同，然后对每组明文分别加密得到密文。加密和解密过程采用相同的密钥，称为对称密码体制。 ​ 例如将明文分为 \(m\) 块： \(P_{0},P_{1},P_2,…,P_{m-1}\) ，每个块在密钥作用下执行相同的变换，生成 \(m\) 个密文块： \(C_0,C_1,C_2,…,C_{m-1}\) ，每块的大小可以是任意长度，但通常是每块的大小大于等于64位（块大小为1比特位时，分组密码就变为序列密码）。 如下图所示是通信双方最常用的分组密码基本通信模型。 ​ 一个分组密码系统(Block Cipher System，简称BCS）可以用一个五元组来表示： \(BCS=\{P,C,K,E,D\}\) 。其中，P(plaintext)、C(ciphertext)、K(key)、E(encryption)、D(decode)分别代表明文空间、密文空间、密钥空间、加密算法、解密算法。 设 \(X=\{x_0,x_1,…,x_{n-2},x_{n-1}\}\) 为一组长度为 \(n\) 的明文块，在密钥 \(K=\{k_0,k_1,…,k_{t-1}\}\) 的加密作用下得到密文块 \(Y=\{y_0,y_1,…,y_{m-2},y_{m-1}\}\) ，其中 \(x_i,y

I need to do some simple DES encryption in C to interface with some old code. From what I understand you can use the "crypt" library for this, with the functions setkey, encrypt, crypt, etc. I have been messing with it and can't get it right. The example on the man page for setkey/encrypt is lacking. I want to get the same output as I would be able to get with some java code (see below). So let's say I have two character arrays in C. char *message = "hellothe"; char *key = "iamakey0"; Can someone give an example of how to encrypt these with setkey/encrypt and get the same result as I would

First of all, I've reviewed all the entries on the forum, and I still can not find a solution to my problem. I have to measure the time it takes to encode and decode a text with DES, and make a comparison with other algorithms. When I run the code, I have this error: BadPaddingException: pad block corrupted . When I debug, the code fails in this line: byte [] plaintext = cipher.doFinal (cipherBytes); I use class Base64 to encode/decode String <--> byte[] Any idea? thanks private static final String CIPHER_ALGORITHM = "DES/ECB/PKCS5Padding"; private static int KEY_LENGTH = 64; public static