MD5 Collision Demo - Hash Function Vulnerabilities

⚠️ MD5 is Cryptographically Broken

MD5 collisions can be generated in seconds on a laptop. Never use MD5 for security purposes. Use SHA-256 or SHA-3 for cryptographic hashing.

Famous Collision Example

Two different files, same MD5 hash - first published by Wang et al. (2004)

📄 File A

d131dd02c5e6eec4693d9a0698aff95c
2fcab58712467eab4004583eb8fb7f89
55ad340609f4b30283e488832571415a
085125e8f7cdc99fd91dbdf280373c5b
d8823e3156348f5bae6dacd436c919c6
dd53e2b487da03fd02396306d248cda0
e99f33420f577ee8ce54b67080a80d1e
c69821bcb6a8839396f9652b6ff72a70
                        

MD5 Hash:

79054025255fb1a26e4bc422aef54eb4

📄 File B

d131dd02c5e6eec4693d9a0698aff95c
2fcab50712467eab4004583eb8fb7f89
55ad340609f4b30283e4888325f1415a
085125e8f7cdc99fd91dbd7280373c5b
d8823e3156348f5bae6dacd436c919c6
dd53e23487da03fd02396306d248cda0
e99f33420f577ee8ce54b67080280d1e
c69821bcb6a8839396f965ab6ff72a70
                        

MD5 Hash:

79054025255fb1a26e4bc422aef54eb4

⚡ COLLISION!

Different input data → Same hash output

79054025255fb1a26e4bc422aef54eb4

MD5 Collision Timeline

1996 Dobbertin finds collision in MD5 compression function

2004 Wang et al. find practical collision in under an hour

2006 Collisions generated in minutes on a laptop

2008 Fake SSL certificate created using MD5 collision

2012 Flame malware uses MD5 collision to fake Microsoft signature

❌ MD5 (Broken)

Output Size 128 bits

Collision Resistance BROKEN

Collision Time Seconds

Use Cases Checksums only

✓ SHA-256 (Secure)

Output Size 256 bits

Collision Resistance 2^128 ops

Collision Time Heat death of universe

Use Cases All cryptographic

Why Collisions Matter

Digital Signatures: If you can create a collision, you can make two documents with the same signature - one innocent, one malicious.

Certificate Attacks: Attackers created fake CA certificates by generating collisions with real certificates.

Integrity Checks: Malware can be hidden in files that have the same hash as legitimate files.

Solution: Always use SHA-256, SHA-3, or BLAKE3 for security-sensitive hashing.