06/24/2021
Top 10 tools you need to master for your hacking career explained : part 5 : Cryptography
5️⃣➡️ Cryptography, or cryptology is the practice and study of techniques for secure communication in the presence of third parties called adversaries.More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, electrical engineering, communication science, and physics. Applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications.
➡️ Cryptography prior to the modern age was effectively synonymous with encryption, converting information from a readable state to unintelligible nonsense. The sender of an encrypted message shares the decoding technique only with intended recipients to preclude access from adversaries. The cryptography literature often uses the names Alice ("A") for the sender, Bob ("B") for the intended recipient, and Eve ("eavesdropper") for the adversary. Since the development of rotor cipher machines in World War I and the advent of computers in World War II, cryptography methods have become increasingly complex and its applications more varied.
➡️Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions, making such algorithms hard to break in actual practice by any adversary. While it is theoretically possible to break into a well-designed system, it is infeasible in actual practice to do so. Such schemes, if well designed, are therefore termed "computationally secure"; theoretical advances, e.g., improvements in integer factorization algorithms, and faster computing technology require these designs to be continually reevaluated, and if necessary, adapted. There exist information-theoretically secure schemes that provably cannot be broken even with unlimited computing power, such as the one-time pad, but these schemes are much more difficult to use in practice than the best theoretically breakable but computationally secure schemes.
➡️ The growth of cryptographic technology has raised a number of legal issues in the information age. Cryptography's potential for use as a tool for espionage and sedition has led many governments to classify it as a weapon and to limit or even prohibit its use and export. In some jurisdictions where the use of cryptography is legal, laws permit investigators to compel the disclosure of encryption keys for documents relevant to an investigation. Cryptography also plays a major role in digital rights management and copyright infringement disputes in regard to digital media.
➡️ Until modern times, cryptography referred almost exclusively to encryption, which is the process of converting ordinary information (called plaintext) into unintelligible form (called ciphertext). Decryption is the reverse, in other words, moving from the unintelligible ciphertext back to plaintext. A cipher (or cypher) is a pair of algorithms that carry out the encryption and the reversing decryption. The detailed operation of a cipher is controlled both by the algorithm and, in each instance, by a "key". The key is a secret (ideally known only to the communicants), usually a string of characters (ideally short so it can be remembered by the user), which is needed to decrypt the ciphertext. In formal mathematical terms, a "cryptosystem" is the ordered list of elements of finite possible plaintexts, finite possible cyphertexts, finite possible keys, and the encryption and decryption algorithms which correspond to each key. Keys are important both formally and in actual practice, as ciphers without variable keys can be trivially broken with only the knowledge of the cipher used and are therefore useless (or even counter-productive) for most purposes.
Some use the terms cryptography and cryptology interchangeably in English, while others (including US military practice generally) use cryptography to refer specifically to the use and practice of cryptographic techniques and cryptology to refer to the combined study of cryptography and cryptanalysis. English is more flexible than several other languages
✴️ essential encryption terms ✴️
🔹Algorithm 🔹
🔸Also known as a cipher, algorithms are the rules or instructions for the encryption process. The key length, functionality, and features of the encryption system in use determine the effectiveness of the encryption.
🔹 Decryption 🔹
🔸Decryption is the process of converting unreadable ciphertext to readable information.
🔹Key 🔹
🔸An encryption key is a randomized string of bits used to encrypt and decrypt data. Each key is unique, and longer keys are harder to break. Typical key lengths are 128 and 256 bits for private keys and 2048 for public keys.
✴️There are two kinds of cryptographic key systems, symmetric, and asymmetric.
🔹🔸Symmetric Key Systems
In a symmetric key system, everyone accessing the data has the same key. Keys that encrypt and decrypt messages must also remain secret to ensure privacy. While it’s possible for this to work, securely distributing the keys to ensure proper controls are in place makes symmetric encryption impractical for widespread commercial use.
🔹🔸Asymmetric Key Systems
An asymmetric key system, also known as a public/private key system, uses two keys. One key remains secret—the private key—while the other key is made widely available to anyone who needs it. This key is called the public key. The private and public keys are mathematically tied together, so the corresponding private key can only decrypt that information encrypted using the public key.
✴️ Common Encryption Algorithms ✴️
🔹🔸Triple DES
Triple DES was designed to replace the original Data Encryption Standard (DES) algorithm, which hackers eventually learned to defeat with relative ease. At one time, Triple DES was the recommended standard and the most widely used symmetric algorithm in the industry.
Triple DES uses three individual keys with 56 bits each. The total key length adds up to 168 bits, but experts would argue that 112-bits in key strength is more accurate. Despite slowly being phased out, Triple DES has, for the most part, been replaced by the Advanced Encryption Standard (AES).
🔹🔸 AES
The Advanced Encryption Standard (AES) is the algorithm trusted as the standard by the U.S. Government and numerous organizations. Although it is highly efficient in 128-bit form, AES also uses keys of 192 and 256 bits for heavy-duty encryption purposes.
AES is largely considered impervious to all attacks, except for brute force, which attempts to decipher messages using all possible combinations in the 128, 192, or 256-bit cipher.
🔹🔸 RSA Security
RSA is a public-key encryption algorithm and the standard for encrypting data sent over the internet. It also happens to be one of the methods used in PGP and GPG programs. Unlike Triple DES, RSA is considered an asymmetric algorithm due to its use of a pair of keys. You’ve got your public key to encrypt the message and a private key to decrypt it. The result of RSA encryption is a huge batch of mumbo jumbo that takes attackers a lot of time and processing power to break.
🔹🔸Blowfish
Blowfish is yet another algorithm designed to replace DES. This symmetric cipher splits messages into blocks of 64 bits and encrypts them individually. Blowfish is known for its tremendous speed and overall effectiveness. Meanwhile, vendors have taken full advantage of its free availability in the public domain. You’ll find Blowfish in software categories ranging from e-commerce platforms for securing payments to password management tools, where it protects passwords. It’s one of the more flexible encryption methods available.
🔹🔸Twofish
Computer security expert Bruce Schneier is the mastermind behind Blowfish and its successor Twofish. Keys used in this algorithm may be up to 256 bits in length, and as a symmetric technique, you only need one key. Twofish is one of the fastest of its kind and ideal for use in hardware and software environments. Like Blowfish, Twofish is freely available to anyone who wants to use it.
✴️ Cryptographic hash function ✴️
➡️ cryptographic hash function (CHF) is a mathematical algorithm that maps data of arbitrary size (often called the "message") to a bit array of a fixed size (the "hash value", "hash", or "message digest"). It is a one-way function, that is, a function which is practically infeasible to invert or to reverse the computation of.Ideally, the only way to find a message that produces a given hash is to attempt a brute-force search of possible inputs to see if they produce a match, or use a rainbow table of matched hashes. Cryptographic hash functions are a basic tool of modern cryptography.
➡️ The ideal cryptographic hash function has the following main properties:
🔹🔸it is deterministic, meaning that the same message always results in the same hash
🔹🔸it is quick to compute the hash value for any given message
🔹🔸it is infeasible to generate a message that yields a given hash value (i.e. to reverse the process that generated the given hash value)
🔹🔸it is infeasible to find two different messages with the same hash value
🔹🔸a small change to a message should change the hash value so extensively that a new hash value appears uncorrelated with the old hash value (avalanche effect)
➡️ Cryptographic hash functions have many information-security applications, notably in digital signatures, message authentication codes (MACs), and other forms of authentication. They can also be used as ordinary hash functions, to index data in hash tables, for fingerprinting, to detect duplicate data or uniquely identify files, and as checksums to detect accidental data corruption. Indeed, in information-security contexts, cryptographic hash values are sometimes called (digital) fingerprints, checksums, or just hash values, even though all these terms stand for more general functions with rather different properties and purposes.
✴️ Cryptographic hash algorithms ✴️
🔹🔸MD5
MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function, MD4, and was specified in 1992 as RFC 1321. Collisions against MD5 can be calculated within seconds which makes the algorithm unsuitable for most use cases where a cryptographic hash is required. MD5 produces a digest of 128 bits (16 bytes).
🔹🔸SHA-1
SHA-1 was developed as part of the U.S. Government's Capstone project. The original specification – now commonly called SHA-0 – of the algorithm was published in 1993 under the title Secure Hash Standard, FIPS PUB 180, by U.S. government standards agency NIST (National Institute of Standards and Technology). It was withdrawn by the NSA shortly after publication and was superseded by the revised version, published in 1995 in FIPS PUB 180-1 and commonly designated SHA-1. Collisions against the full SHA-1 algorithm can be produced using the shattered attack and the hash function should be considered broken. SHA-1 produces a hash digest of 160 bits (20 bytes).
🔹🔸 RIPEMD-160
RIPEMD (RACE Integrity Primitives Evaluation Message Digest) is a family of cryptographic hash functions developed in Leuven, Belgium, by Hans Dobbertin, Antoon Bosselaers, and Bart Preneel at the COSIC research group at the Katholieke Universiteit Leuven, and first published in 1996. RIPEMD was based upon the design principles used in MD4 and is similar in performance to the more popular SHA-1. RIPEMD-160 has, however, not been broken. As the name implies, RIPEMD-160 produces a hash digest of 160 bits (20 bytes)
🔹🔸Whirlpool
Whirlpool is a cryptographic hash function designed by Vincent Rijmen and Paulo S. L. M. Barreto, who first described it in 2000. Whirlpool is based on a substantially modified version of the Advanced Encryption Standard (AES). Whirlpool produces a hash digest of 512 bits (64 bytes).
🔹🔸SHA-2
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA), first published in 2001. They are built using the Merkle–Damgård structure, from a one-way compression function itself built using the Davies–Meyer structure from a (classified) specialized block cipher.
SHA-2 basically consists of two hash algorithms: SHA-256 and SHA-512. SHA-224 is a variant of SHA-256 with different starting values and truncated output. SHA-384 and the lesser-known SHA-512/224 and SHA-512/256 are all variants of SHA-512. SHA-512 is more secure than SHA-256 and is commonly faster than SHA-256 on 64-bit machines such as AMD64.
The output size in bits is given by the extension to the "SHA" name, so SHA-224 has an output size of 224 bits (28 bytes); SHA-256, 32 bytes; SHA-384, 48 bytes; and SHA-512, 64 bytes.
🔹🔸SHA-3
SHA-3 (Secure Hash Algorithm 3) was released by NIST on August 5, 2015. SHA-3 is a subset of the broader cryptographic primitive family Keccak. The Keccak algorithm is the work of Guido Bertoni, Joan Daemen, Michael Peeters, and Gilles Van Assche. Keccak is based on a sponge construction which can also be used to build other cryptographic primitives such as a stream cipher. SHA-3 provides the same output sizes as SHA-2: 224, 256, 384, and 512 bits.
Configurable output sizes can also be obtained using the SHAKE-128 and SHAKE-256 functions. Here the -128 and -256 extensions to the name imply the security strength of the function rather than the output size in bits.
🔹🔸BLAKE2
BLAKE2, an improved version of BLAKE, was announced on December 21, 2012. It was created by Jean-Philippe Aumasson, Samuel Neves, Zooko Wilcox-O'Hearn, and Christian Winnerlein with the goal of replacing the widely used but broken MD5 and SHA-1 algorithms. When run on 64-bit x64 and ARM architectures, BLAKE2b is faster than SHA-3, SHA-2, SHA-1, and MD5. Although BLAKE and BLAKE2 have not been standardized as SHA-3 has, BLAKE2 has been used in many protocols including the Argon2 password hash, for the high efficiency that it offers on modern CPUs. As BLAKE was a candidate for SHA-3, BLAKE and BLAKE2 both offer the same output sizes as SHA-3 – including a configurable output size.
🔹🔸BLAKE3
BLAKE3, an improved version of BLAKE2, was announced on January 9, 2020. It was created by Jack O'Connor, Jean-Philippe Aumasson, Samuel Neves, and Zooko Wilcox-O'Hearn. BLAKE3 is a single algorithm, in contrast to BLAKE and BLAKE2, which are algorithm families with multiple variants. The BLAKE3 compression function is closely based on that of BLAKE2s, with the biggest difference being that the number of rounds is reduced from 10 to 7. Internally, BLAKE3 is a Merkle tree, and it supports higher degrees of parallelism than BLAKE2.
✴️ Attacks on hashed passwords ✴️
➡️ A common use of hashes is to store password authentication data. Rather than store the plaintext of user passwords, a controlled access system stores the hash of each user's password in a file or database. When someone requests access, the password they submit is hashed and compared with the stored value. If the database is stolen (an all too frequent occurrence ), the thief will only have the hash values, not the passwords.
However, most people choose passwords in predictable ways. Lists of common passwords are widely circulated and many passwords are short enough that all possible combinations can be tested if fast hashes are used. The use of cryptographic salt prevents some attacks, such as building files of precomputing hash values, e.g. rainbow tables. But searches on the order of 100 billion tests per second are possible with high-end graphics processors, making direct attacks possible even with salt.
🆘 Useful tools 🆘
➡️ findmyhash Package Description
🔹Accepted algorithms are:
🔸MD4 – RFC 1320
🔸MD5 – RFC 1321
🔸SHA1 – RFC 3174 (FIPS 180-3)
🔸SHA224 – RFC 3874 (FIPS 180-3)
🔸SHA256 – FIPS 180-3
🔸SHA384 – FIPS 180-3
🔸SHA512 – FIPS 180-3
🔸RMD160 – RFC 2857
🔸GOST – RFC 583
🔸WHIRLPOOL – ISO/IEC 10118-3:2004
🔸LM – Microsoft Windows hash NTLM – 🔸Microsoft Windows hash
🔸MYSQL – MySQL 3, 4, 5 hash
🔸CISCO7 – Cisco IOS type 7 encrypted passwords
🔸JUNIPER – Juniper Networks $9$ encrypted passwords
🔸LDAP_MD5 – MD5 Base64 encoded
🔸LDAP_SHA1 – SHA1 Base64 encoded.
➡️ hashcat Package Description
🔹hashcat is the world’s fastest and most advanced password recovery utility, supporting five unique modes of attack for over 200 highly-optimized hashing algorithms. hashcat currently supports CPUs, GPUs, and other hardware accelerators on Linux, Windows, and OSX, and has facilities to help enable distributed password cracking.
Ps: hashcat and findmyhash can be found pre-installed in kali linux
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