Shell script to bruteforce SSH key with openssl using multi threads

crack_key_threads.sh

#!/bin/bash

export THREADS=8
export WORDLIST='/opt/wordlists/rockyou.txt'
export PREFIX='/tmp/rockyou_'

# Generate N wordlists chunks
split -n "$THREADS" --numeric-suffixes=1 "$WORDLIST" "$PREFIX"

# Function to break the passwords given a list
function break_key() {
    for guess in $(cat $1)
    do
        openssl rsa -in encrypted.key -out cracked.key -passin pass:$guess &> /dev/null &&
        echo "Key found! $guess" && 
        exit 0
    done
}

for n in $(seq -w 01 "$THREADS")
do
    echo "Starting thread #${n}..."
    break_key ${PREFIX}${n} &
done

wait
echo "Key not found!"