How to identify and crack a Java KeyStore (JKS) private key hash

Java KeyStore (JKS) private key is a application hash type. It is fast and typically unsalted, which makes weak passwords recoverable quickly on consumer GPU hardware. This page shows how to recognise it and the exact commands to attack it.

All identification runs locally in WebAssembly. The commands below write the hash to a local file on your machine — nothing is sent to this site.

Identifying the hash

The hash identifier on the home page detects Java KeyStore (JKS) private key entirely in your browser — your hash is never uploaded. A typical example looks like this:

$jksprivk$*338F1F...*5A0E...*test

Cracking Java KeyStore (JKS) private key with hashcat

Save the hash to a file and run hashcat in mode -m 15500. Start with a wordlist such as rockyou.txt:

echo '$jksprivk$*338F1F...*5A0E...*test' > hash.txt && hashcat -m 15500 hash.txt /usr/share/wordlists/rockyou.txt

Add a rule set to mutate dictionary words (capitalisation, leetspeak, appended digits) and dramatically widen coverage:

echo '$jksprivk$*338F1F...*5A0E...*test' > hash.txt && hashcat -m 15500 hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/best64.rule

Cracking Java KeyStore (JKS) private key with John the Ripper

John the Ripper can attack the same hash with the jks-keystore format:

echo '$jksprivk$*338F1F...*5A0E...*test' > hash.txt && john --format=jks-keystore --wordlist=/usr/share/wordlists/rockyou.txt hash.txt