If you are writing an application using CAST then you don't need to bother about the implementation of the algorithm.You pass the encrypted buffer, mechanism(CAST) and mode(CFB) to the decrypt function.
If you are implementing the algorithm then you definitely need to take care of IV that is initialization vector which is used for increasing the randomness of encryption. Hope it will help. regards, Bhishm -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, November 20, 2002 3:24 PM To: [EMAIL PROTECTED] Subject: give me some advice about CFB /* The data is encrypted in CFB mode, with a CFB shift size equal to the cipher's block size. The Initial Vector (IV) is specified as all zeros. Instead of using an IV, OpenPGP prefixes a 10-octet string to the data before it is encrypted. The first eight octets are random, and the 9th and 10th octets are copies of the 7th and 8th octets, respectively. After encrypting the first 10 octets, the CFB state is resynchronized if the cipher block size is 8 octets or less. The last 8 octets of ciphertext are passed through the cipher and the block boundary is reset. */ If a plaintext is encrpted with CAST using this CFB mode, and i know the session key and the ciphertext, how can I decrpyt it, i have tried many times, but still can't recovery the plaintext. In fact, i havn't grasped the meaning of the above paragraph. any help thanks best regards ________________ USTC Alumni Email System, http://mail.ustc.edu, FREE Signup. ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED] ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]
