Cryptography

Todo empezó con una idea que llevaba tiempo rondándome la cabeza » flu-project.com | flu-project.com

Cryptography functionality in the Wolfram Language supports generation and verification of digital signatures for expressions, files and cloud objects. Encrypt or digitally sign anything—from simple messages to images or code. » Diego Olvera | blog.wolfram.com

Los certificados TSL, anteriormente conocidos como certificados SSL son otra forma de llamar a los certificados de clave pública X.509. Julia Evans ha hecho una gran labor explicando en su blog cómo es uno de estos certificados «por dentro» de forma… » @Alvy | microsiervos.com

Llegan las navidades, aunque comercialmente ya empezaron hace casi un mes, y que mejor que dar ideas para regalar o ser regalado. ¿No sabes que encargarle a los reyes magos? No te preocupes, vamos a comentar los 10 libros de seguridad informática que más leemos en Hispasec. Esos que yacen desgastados en los escritorios de auditoría, malware o el equipo 24x7 de Antifraude, nuestros incansables vigilantes. Leer y hacer son dos palabras claves en la construcción de un buen profesional, sea de la rama que sea. La formación es importante y una de las cosas que siempre ha estado presente en Hispasec es que el personal no le falte lectura, alimento para el cerebro. ...

It’s universally acknowledged that it’s a bad idea to store plain-text passwords. If a database containing plain-text passwords is compromised, user accounts are in immediate danger. For this reason, as early as 1976, the industry standardized on storing passwords using secure, one-way hashing mechanisms (starting with Unix Crypt). Unfortunately, while this prevents the direct reading of passwords in case of a compromise, all hashing mechanisms necessarily allow attackers to brute force the hash offline, by going through lists of possible passwords, hashing them, and comparing the result. In this context, secure hashing functions like SHA have a critical flaw for password hashing: they are designed to be fast. A modern commodity CPU can generate millions of SHA256 hashes per second. Specialized GPU clusters allow for calculating hashes at a rate of billions per second. ...

We demonstrate the extraction of secret decryption keys from laptop computers, by nonintrusively measuring electromagnetic emanations for a few seconds from a distance of 50 cm. The attack can be executed using cheap and readily-available equipment: a consumer-grade radio receiver or a Software Defined Radio USB dongle. The setup is compact and can operate untethered; it can be easily concealed, e.g., inside pita bread. Common laptops, and popular implementations of RSA and ElGamal encryptions, are vulnerable to this attack, including those that implement the decryption using modern exponentiation algorithms such as sliding-window, or even its side-channel resistant variant, fixed-window (m-ary) exponentiation. We successfully extracted keys from laptops of various models running GnuPG (popular open source encryption software, implementing the OpenPGP standard), within a few seconds. The attack sends a few carefully-crafted ciphertexts, and when these are decrypted by the target computer, they trigger the occurrence of specially-structured values inside the decryption software. These special values cause observable fluctuations in the electromagnetic field surrounding the laptop, in a way that depends on the pattern of key bits (specifically, the key-bits window in the exponentiation routine). The secret key can be deduced from these fluctuations, through signal processing and cryptanalysis. ...

A group of cryptographers at INRIA, Microsoft Research and IMDEA have discovered some serious vulnerabilities in OpenSSL (e.g., Android) clients and Apple TLS/SSL clients (e.g., Safari) that allow a ’man in the middle attacker’ to downgrade connections from ’strong’ RSA to ’export-grade’ RSA. These attacks are real and exploitable against a shocking number of websites – including government websites. » Matthew Green | blog.cryptographyengineering.com

Reading the documents, I have the feeling that the NSA can 1) decrypt weak crypto and 2) steal keys. Let’s focus on the crypto first. SSH supports different key exchange algorithms, ciphers and message authentication codes. The server and the client choose a set of algorithms supported by both, then proceed with the key exchange. Some of the supported algorithms are not so great and should be disabled completely. If you leave them enabled but prefer secure algorithms, then a man in the middle might downgrade you to bad ones. This hurts interoperability but everyone uses OpenSSH anyway. ...

My colleague, Bodo M¶ller, in collaboration with Thai Duong and Krzysztof Kotowicz (also Googlers), just posted details about a padding oracle attack against CBC-mode ciphers in SSLv3. This attack, called POODLE, is similar to the BEAST attack and also allows a network attacker to extract the plaintext of targeted parts of an SSL connection, usually cookie data. Unlike the BEAST attack, it doesn’t require such extensive control of the format of the plaintext and thus is more practical. Fundamentally, the design flaw in SSL/TLS that allows this is the same as with Lucky13 and Vaudenay’s two attacks: SSL got encryption and authentication the wrong way around – it authenticates before encrypting. ...

In March, readers followed along as Nate Anderson, Ars deputy editor and a self-admitted newbie to password cracking, downloaded a list of more than 16,000 cryptographically hashed passcodes. Within a few hours, he deciphered almost half of them. The moral of the story: if a reporter with zero training in the ancient art of password cracking can achieve such results, imagine what more seasoned attackers can do. Imagine no more. We asked three cracking experts to attack the same list Anderson targeted and recount the results in all their color and technical detail Iron Chef style. The results, to say the least, were eye opening because they show how quickly even long passwords with letters, numbers, and symbols can be discovered. ...