文件名称：DES资料详细介绍
文件大小：294KB
文件格式：ZIP
更新时间：2015-03-13 19:15:35
DES ，CBC,ECB
Electronic Codebook Mode (ECB),Cipher Block Chaining Mode (CBC).Cipher Feedback Mode (CFB) Only blocks of j <= 64 bits are enciphered at a time. A small j requires more cycles through the encipherment algorithm per unit of plaintext and thus greater processing overhead. A plaintext block always produces the same ciphertext block for the same key and starting variable. Blocks cannot be rearranged. Each ciphertext block depends on the current and all preceding plaintext blocks. Different starting variables are used to prevent the same plaintext enciphering to the same ciphertext. The strength of this mode depends on the size of the key k (best if j == k). An error will affect the current and the following ciphertext blocks. Output Feedback Mode (OFB) Only blocks of j <= 64 bits are enciphered at a time. A small j requires more cycles through the encipherment algorithm per unit of plaintext and thus greater processing overhead. A plaintext block always produces the same ciphertext block for the same key and starting variable. Different starting variables are used to prevent the same plaintext enciphering to the same ciphertext. Absence of chaining makes this mode vulnerable to specific attacks. Different start variable values prevent the same plaintext enciphering to the same ciphertext, by producing different key streams. An error bit in the ciphertext causes only one bit to be in error in the deciphered plaintext. It is not self-synchronizing. Triple-DES ECB Mode Encrypt with key1, decrypt with key2 and encrypt with key3 again. As for ECB encryption but increases the key length to 168 bits. If all keys are the same it is equivalent to encrypting once with just one key. If the first and last key are the same, the key length is 112 bits. If all 3 keys are the same, this is effectively the same as normal ECB mode. Triple-DES CBC Mode Encrypt with key1, decrypt with key2 and then encrypt with key3. As for CBC encryption but increases the key length to 168 bits with the same restrictions as the Triple-DES ESB mode Our first example shows how to use the basic DES encryption routine, DES_ecb_encrypt(), to encrypt or decrypt a single 64-bit block of plaintext to electronic code book (ECB) mode. If the encrypt argument is DES_ENCRYPT, the input (plaintext) is encrypted into the output (ciphertext) using the specified key_schedule. If the encrypt argument is DES_DECRYPT, the input (ciphertext) is decrypted into the output (plaintext). Note that input and output may overlap. Read more: http://blog.fpmurphy.com/2010/04/openssl-des-api.html#ixzz1n2Qte3UG
【文件预览】：
des资料
----DES算法详细介绍.wps(898KB)
----Des.cpp.txt(15KB)
----论坛DES算法.wps(225KB)