OSPF V3 Hash methods

A cryptographic hash function (CHF) is an equation that is widely used to verify the validity of data. It has many applications, particularly in information security (e.g. user authentication). A CHF translates data of various lengths into a fixed-size numerical string (Hashed Text). A cryptographic hash function is single-directional and it is extremely difficult to reverse to recreate the information used to make it.

OSPF (Open Shortest Path First) is a widely used routing protocol in networks. It is a link-state protocol, which means it maintains a map (or "topology") of the network and uses that map to calculate the shortest path to each destination. OSPF primarily uses MD5 for authentication purposes to ensure that the routing information is from a trusted source. RFC 2328 specifies the OSPFv2 protocol, which includes the option to use MD5 for authenticating OSPF messages to ensure the integrity and authenticity of routing exchanges.

Advantages of MD5 Algorithm

• MD5 is faster and simple to understand.
• MD5 algorithm generates a strong password in 16 bytes format. All developers like web developers, etc. use the MD5 algorithm to secure the password of users.?
• To integrate the MD5 algorithm, relatively low memory is necessary.?
• It is very easy and faster to generate a digest message of the original message.

Disadvantages of MD5 Algorithm

• MD5 generates the same hash function for different inputs (hash collision).?
• MD5 provides poor security over SHA1, SHA256 and other modern cryptographic algorithms.
• MD5 has been considered an insecure algorithm. So now we are using SHA256 instead of MD5.?
• MD5 is neither a symmetric nor asymmetric algorithm.

Alternatives to MD5 in Modern Cryptography

As MD5 has been found to have vulnerabilities, several more secure cryptographic hash functions are commonly used in modern applications:

1. SHA-256 (Secure Hash Algorithm 256-bit) is a part of the SHA-2 family that produces a 256-bit hash value. It is widely used in blockchain, SSL certificates, digital signatures, and certificates.
2. SHA-3 offers an alternative to SHA-2 with a different internal structure, making it more resilient to certain attacks. While SHA-2 is still more common, SHA-3 is used for secure applications requiring the highest cryptographic standards.
3. RIPEMD-160 produces a 160-bit hash value, providing better security than MD5 but not as widely used as SHA-2. It is sometimes used in digital signatures and certificates in specific security systems.
4. Whirlpool is a cryptographic hash function designed for high security, producing a 512-bit hash output. It’s used particularly in cases where very strong security is required.

OSPF can work with other hashing methods as well, especially as concerns have grown about MD5's vulnerabilities. For enhanced security, newer implementations and extensions allow OSPF to use more secure hash functions such as SHA (Secure Hash Algorithm). These are typically implemented through extensions to the OSPF protocol, like OSPFv3, which includes support for more robust cryptographic methods. OSPFv3 is specified in RFC 5340 and it extends OSPF to support IPv6 networking. in below wireshark snapshot you can see a IPv6 packet Authentication header.

Images from:

https://networkingbodges.blogspot.com/2013/10/offline-attack-on-md5-keys-in-captured.html

https://www.geeksforgeeks.org/what-is-the-md5-algorithm/

https://networklessons.com/ipv6/ospfv3-authentication-and-encryption