Ebook Data-Driven Block ciphers for fast telecommunication systems. Among different directions of applied cryptography, the cipher design based on the data-driven operations (DDOs) is, by comparison, poorly represented in the published and available literature.
USE OF MODERN BLOCK CIPHERS
Symmetric-key encipherment can be done
using modern block ciphers. Modes of
operation have been devised to encipher text of
any size employing either DES or AES.
A single bit error in transmission can create errors in
several in the corresponding block.
USE OF MODERN BLOCK CIPHERS
Symmetric-key encipherment can be done using modern block ciphers. Modes of operation have been devised to encipher text of any size employing either DES or AES.
1 USE OF MODERN BLOCK CIPHERS
Electronic codebook (ECB) mode
Error Propagation A single bit error in transmission can create errors in several in the corresponding block. However, the error does not have any effect on the other blocks.
How many padding bits must be added to a message of 100 characters if
ASCII is used for encoding and the block cipher accepts blocks of 64
Suppose that we have a block cipher where n = 64. If there are 10 1’s in
the ciphertext, how many trialanderror
tests does Eve need to do to
recover the plaintext from the intercepted ciphertext in each of the
How many padding bits must be added to a message of 100 characters if 8-bit ASCII is used for encoding and the block cipher accepts blocks of 64 bits?
1 MODERN BLOCK CIPHERS
Substitution or Transposition ?
To be resistant to exhaustive-search attack, a modern block cipher needs to be designed as a substitution cipher.
Suppose that we have a block cipher where n = 64. If there are 10 1’s in the ciphertext, how many trial-and-error tests does Eve need to do to recover the plaintext from the intercepted ciphertext in each of the following cases? a. The cipher is designed as a...
Simple Des is a block cipher which encrypts an 9 bit block of plaintext using a 10 bit key and outputs an 8 bit block of ciphertext.This Simple Des presents of structure of Simple Des; basic fuctions of Simple Des; crypanalysis of Simple Des and some things else.
In this book, we strive to present applied cryptanalytic attacks in an acces- sible form. Here, we are focused on practical attacks that actually break real- world systems, not attacks that merely indicate some theoretical weakness in a cipher.
Symmetric Block Ciphers
Chương này sẽ đề cập với một số thuật toán mật mã khối quan trọng đã được phát triển trong quá khứ. Họ là IDEA (1992), RC5 (1995), rc6 (1996), DES (1977) và AES (2001). Advanced Encryption Standard (AES) xác định một thuật toán mã hóa FIPS-phê duyệt khối đối xứng sẽ sớm đến để được sử dụng thay cho Triple DES hoặc rc6.
Các khái niệm và nguyên lý thiết kế cơ sở
Các hệ mật mã cổ điển được giới thiệu trong chương trước đều thuộc loại mật mã dòng (stream cipher), trong đó phép biển đổi mật mã thực hiện trên từng ký tự độc lập. Tuy nhiên ngày nay được ưa chuộng sử dụng hơn là một kiểu mật mã khác – mật mã khối (block cipher) -- trong đó từng khối nhiều ký tự được mã hóa cùng một lúc.
Stream ciphers are an important class of encryption algorithms. They encrypt individual
characters (usually binary digits) of a plaintext message one at a time, using an encryption
transformation which varies with time. By contrast, block ciphers (Chapter 7) tend to
simultaneously encrypt groups of characters of a plaintext message using a fixed encryption
transformation. Stream ciphers are generally faster than block ciphers in hardware,
and have less complex hardware circuitry. They are also more appropriate, and in some
cases mandatory (e.g.
Threat Discovery Services provides corporatewide traffic threat detection and
analysis capabilities via a threat discovery appliance or any VMware-based system. It
is deployed out of band at the network layer on the core switch, where it can monitor
the stealth techniques being used by modern malware to provide 24 x 7 network
monitoring and detection of hidden malware infections.
The threat discovery technology detects day-zero infections by leveraging Trend
Micro Smart Protection Network and multiple threat analysis engines.
We will use whether or not the household owns animals, bikes and/or motorbikes. Households living
in the rural part of the municipality might be more prone to own these assets. Moreover, they might
have worse access to health and sanitary infrastructure. If this was the case, we expect that the
importance of household consumption will be underestimated when we use the ownership of animals,
bikes and/or motorbikes as instruments.
Impersonation can come about from packet spooﬁng and replay attacks. Spooﬁng attacks
involve providing false information about a principal’s identity to obtain unauthorized
access to systems and their services. A replay attack can be a kind of spooﬁng attack
because messages are recorded and later sent again, usually to exploit ﬂaws in authenti-
cation schemes. Both spooﬁng and replay attacks are usually a result of information gained
Overall, the microfinance sector is continuing to expand despite tremendous operating obstacles
in serving the market in a sustainable way. The lack of access to financial services for households
and micro and small enterprises is quite striking in Africa and microfinance institutions are crucial in
responding to the unbanked segments. However, the microfinance sector is still relatively small and
weak compared to other global regions and despite the huge potential market. In this context, the
role of savings banks in microfinance should be recognised and boosted.
Advanced Encryption Standard competition began in 1997
Rijndael was selected to be the new AES in 2001
AES basic structures:
block cipher, but not Feistel cipher
encryption and decryption are similar, but not symmetrical
basic unit: byte, not bit
block size: 16-bytes (128 bits)
three different key lengths: 128, 192, 256 bits
AES-128, AES-192, AES-256
each 16-byte block is represented as a 4 x 4 square matrix, called the state matrix
the number of rounds depends on key lengths
4 simple operations on the state matrix every round (except the last round)
Although the covered topics may not be an exhaustive representation of all the
security issues in wireless/mobile networks, they do represent a rich and useful sample
of the strategies and contents.
This book has been made possible by the great efforts and contributions of many
people. First of all, we would like to thank all the contributors for putting together
excellent chapters that are very comprehensive and informative. Second, we would
like to thank all the reviewers for their valuable suggestions and comments which have
greatly enhanced the quality of this book.
Chương này giới thiệu về mã đối xứng hiện đại - Mã khối. Những nội dung chính được đề cập đến trong chương này gồm: Mã khối (Block Cipher), mạng SPN, mã TinyDES, các vòng của TinyDES, khả năng chống phá mã known-plaintext của TinyDES,... Mời các bạn cùng tham khảo.
Các kiểu thao tác đầu tiên được đề nghị (ECB, CBC, OFB, CFB) đảm bảo tính bí mật (confidentiality), không giúp đảm bảo tính toàn vẹn thông tin (message integrity). Các kiểu thao tác được thiết kế cho phép (CCM, EAX và OCB) vừa đảm bảo tính bí mật, vừa đảm bảo xác định tính toàn vẹn thông tin.