Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Mỗi chạy nên chọn một muối khác nhau và tương ứng tạo ra một bản mã khác nhau. Khi trạng thái trình diễn, chúng tôi sẽ chỉ có được muối và bản mã để có thể giải mã nó (miễn là chúng ta biết mật khẩu). Chúng tôi không phải gửi các byte IV kể từ khi họ có nguồn gốc từ PKCS # 5 thuật toán. | 248 Chapter 5 Hash Functions The example output would resemble the following. We give out salt and ciphertext as the output salt 0. 7 58 56 52 f6 9c 04 b5 72 ciphertext 0. 31 e2 3f be 1f 1a 0c f8 96 0c e5 50 04 c0 a8 f7 f0 c4 27 60 ff b5 be bb bc f4 dc 88 ec 0e 0a f4 e6 hello world how are you Each run should choose a different salt and respectively produce a different ciphertext. As the demonstration states we would only have to be given the salt and ciphertext to be able to decrypt it provided we knew the password . We do not have to send the IV bytes since they are derived from the PKCS 5 algorithm. Frequently Asked Questions The following Frequently Asked Questions answered by the authors of this book are designed to both measure your understanding of the concepts presented in this chapter and to assist you with real-life implementation of these concepts. To have your questions about this chapter answered by the author browse to www.syngress.com solutions and click on the Ask the Author form. Q What is a hash function A A hash function accepts as input an arbitrary length string of bits and produces as output a fixed size string of bits known as the message digest. The goal of a cryptographic hash function is to perform the mapping as if the function were a random function. Q What is a message digest A A message digest is the output of a hash function. Usually it is interpreted as a representative of the message. Q What does one-way and collision resistant mean A A function that is one-way implies that determining the output given the input is a hard problem to solve. In this case given a message digest finding the input should be hard. An ideal hash function is one-way. Collision resistant implies that finding pairs of unique inputs that produce the same message digest is a hard problem. There are two forms of collision resistance. The first is called pre-image collision resistance which implies given a fixed message we cannot find another message that .