"YOLO" is not a valid hash construction
The article warns against insecure ad-hoc cryptographic practices, highlighting vulnerabilities in custom constructions. It advocates for established alternatives like HMAC, KMAC, and modern key derivation functions for better security.
Read original article
The article discusses the common pitfalls in cryptographic practices, particularly the use of ad-hoc or "YOLO" constructions that attempt to create custom hash functions or message authentication codes (MACs) without proper understanding. It highlights several problematic constructions, such as YoloMultiHash, YoloMAC, and YoloPBKDF, which can lead to security vulnerabilities like ambiguous encoding, length-extension attacks, and inadequate key derivation from passwords. The author emphasizes that these issues arise from a lack of awareness of established cryptographic standards and solutions. Instead of relying on these insecure methods, the article recommends using well-defined alternatives like TupleHash for hashing multiple values, HMAC or KMAC for MACs, and modern password key derivation functions such as Argon2 or scrypt. These alternatives are designed to address the specific security challenges posed by their predecessors, ensuring better protection against potential attacks.
- Ad-hoc cryptographic constructions often lead to significant security vulnerabilities.
- Established alternatives like HMAC, KMAC, and TupleHash provide robust solutions to common cryptographic needs.
- Modern password key derivation functions, such as Argon2 and scrypt, are essential for secure key generation.
- Awareness of cryptographic standards is crucial to avoid insecure implementations.
- Length-extension attacks and ambiguous encoding are common issues with poorly designed hash functions and MACs.
Related
Radius/UDP. How legacy protocols need to keep up with modern cryptography
Researchers found a new attack on MD5 affecting RADIUS/UDP authentication. Dubbed Blast-RADIUS, it exploits MD5 weaknesses to gain unauthorized access to network devices. Upgrading legacy protocols like RADIUS is crucial for security.
Six Dumbest Ideas in Computer Security
In computer security, common misconceptions like "Default Permit," "Enumerating Badness," and "Penetrate and Patch" hinder effective protection. Emphasizing a "Default Deny" policy and proactive security design is crucial.
Dan Geer on CrowdStrike: It Is Time to Act
The article highlights cybersecurity challenges amid global outages, emphasizing the need for integrated security policies, redundancy in systems, and proactive measures to prevent silent failures and vulnerabilities in technology.
Study finds organizations have a significant gap in security on macOS endpoints
A study by Picus Security reveals macOS endpoints prevent only 23% of cyberattacks, with rising malware threats and weak security practices, emphasizing the need for enhanced security measures in organizations.
Security Issues in Matrix's Olm Library
The Matrix's Olm library has critical cryptographic vulnerabilities, including cache-timing attacks and malleable signatures. The security team will not address these issues, advising users to switch to the vodozemac library.
- Several commenters express skepticism about the complexity and practicality of certain key derivation functions (KDFs) and their recommendations.
- There is a discussion on the importance of encoding methods, with some suggesting JSON as a solution to ambiguous encoding issues.
- Concerns are raised about the real-world implications of following certain cryptographic guidelines, particularly regarding performance and denial-of-service (DoS) vulnerabilities.
- Some commenters emphasize the need for better education on cryptography to prevent misuse of cryptographic primitives.
- There is a general consensus that the article may be too technical for non-specialists, making it less accessible to a broader audience.
12 commentsWhat I have done in the past for this is to encode the messages as UTF-8 and separate them by 0xFF, since that byte value never occurs in UTF-8 encoding [0]. If the messages to be hashed are character strings, you have to decide on some encoding anyway in order to hash them.
[0] UTF-8 bytes always contain at least one zero bit: https://en.wikipedia.org/wiki/UTF-8#Encoding. Incidentally, if one wanted to create the UTF-8 equivalent of zero-terminated strings without reserving a character value (like NUL) as the sentinel value, one could use 0xFF for that.
A lot of assumptions, or just that it's fixed length?
Proto bufs don't guarantee consistent serialization.
- 100s of hashes?
- 1000s of hashes?
- 1,000,000s of hashes?
ambiguous encoding? Nothing ambiguous about JSON, you don't even need any separator. Or merge them into json array.
length-extension attacks? appending non-whitespace to json makes it invalid (for sane decoders at least)
It's hard to understand for non-crypto specialists. It uses notions which are unknown to most programmers like MAC or other *MACs.
So not sure who is the target audience for this.
Related
Radius/UDP. How legacy protocols need to keep up with modern cryptography
Researchers found a new attack on MD5 affecting RADIUS/UDP authentication. Dubbed Blast-RADIUS, it exploits MD5 weaknesses to gain unauthorized access to network devices. Upgrading legacy protocols like RADIUS is crucial for security.
Six Dumbest Ideas in Computer Security
In computer security, common misconceptions like "Default Permit," "Enumerating Badness," and "Penetrate and Patch" hinder effective protection. Emphasizing a "Default Deny" policy and proactive security design is crucial.
Dan Geer on CrowdStrike: It Is Time to Act
The article highlights cybersecurity challenges amid global outages, emphasizing the need for integrated security policies, redundancy in systems, and proactive measures to prevent silent failures and vulnerabilities in technology.
Study finds organizations have a significant gap in security on macOS endpoints
A study by Picus Security reveals macOS endpoints prevent only 23% of cyberattacks, with rising malware threats and weak security practices, emphasizing the need for enhanced security measures in organizations.
Security Issues in Matrix's Olm Library
The Matrix's Olm library has critical cryptographic vulnerabilities, including cache-timing attacks and malleable signatures. The security team will not address these issues, advising users to switch to the vodozemac library.