Go - sort

sort 是 Go 裏面數一數二常用的package，下面介紹三種函式。

Ints

最基本的整數由小到大排序。

package main

import (
	"fmt"
	"sort"
)

func main() {
	s := []int{5, 2, 6, 3, 1, 4} // unsorted
	sort.Ints(s)
	fmt.Println(s)
  // [1 2 3 4 5 6]
}

Strings

最基本的字串由小到大排序。

package main

import (
	"fmt"
	"sort"
)

func main() {
	s := []string{"Go", "Bravo", "Gopher", "Alpha", "Grin", "Delta"}
	sort.Strings(s)
	fmt.Println(s)
  // [Alpha Bravo Delta Go Gopher Grin]
}

Slice

依照給訂的規則來排序，並不保證 stable ，如果想要確保 stable ，可以用另一個函式叫做 SliceStable

import (
	"fmt"
	"sort"
)

func main() {
	people := []struct {
		Name string
		Age  int
	}{
		{"Gopher", 7},
		{"Alice", 55},
		{"Vera", 24},
		{"Bob", 75},
	}
	sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })
	fmt.Println("By name:", people)
  // By name: [{Alice 55} {Bob 75} {Gopher 7} {Vera 24}]

	sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })
	fmt.Println("By age:", people)
  // By age: [{Gopher 7} {Vera 24} {Alice 55} {Bob 75}]
}

Go - Convert int to string

An integer can be converted to string by Itoa function which is in strconv library.
Example :

import (
	"fmt"
	"reflect"
	"strconv"
)

func main() {
	nums1 := 10
	fmt.Println(nums1, reflect.TypeOf(nums1))
	str := strconv.Itoa(nums1)
	fmt.Println(str, reflect.TypeOf(str))
}

unknown feature `proc_macro_span_shrink`

I encounter below error when run command anchor build.

error[E0635]: unknown feature `proc_macro_span_shrink`

Solution is downgrading proc-macro2 to 1.0.43 :

cargo update -p proc-macro2 --precise 1.0.43

Reference

PicoCTF - WPA-ing Out

Challenge

Tags

PicoGym Exclusive / Forensics

Description

I thought that my password was super-secret, but it turns out that passwords passed over the AIR can be CRACKED, especially if I used the same wireless network password as one in the rockyou.txt credential dump.
Use this ‘pcap file’ and the rockyou wordlist. The flag should be entered in the picoCTF{XXXXXX} format.

Prereguisite

Aircrack-Ng, which is a network software suite consisting of a detector, packet sniffer, WEP and WPA/WPA2-PSK cracker and analysis tool for 802.11 wireless LANs.

Writeup

1. Download the pcap file and rockyou wordlist.
2. Crack

   
    aircrack-ng -w rockyou.txt wpa-ing_out.pcap
   
   

   

PicoCTF - WebNet1

Challenge

Tags

PicoCTF 2019 / Forensics

Description

We found this packet capture and key. Recover the flag.

Prereguisite

ssldump, which is an SSL/TLS network protocol analyzer.

Writeup

1. Download packet capture and key.
2. ssldump -r capture.pcap -k picopico.key -d > output
3. vim output
4. Search our flag.