Cryptography

Ciphers

Cipher Identifier & Analyzer

ROT13

Online ROT13 encoder.

# Alias
alias rot13="tr 'A-Za-z' 'N-ZA-Mn-za-m'"

# Encrypt
echo '<plaintext>' | tr 'A-Za-z' 'N-ZA-Mn-za-m'

# Decrypt
echo '<ciphertext>' | tr 'N-ZA-Mn-za-m' 'A-Za-z'

ROT13.5

The ROT13.5 cipher is: ROT13 for letters and ROT5 for numbers.

# Encrypt
echo '<plaintext>' | tr 'A-Za-z0-9' 'N-ZA-Mn-za-m5-90-4'

# Decrypt
echo '<ciphertext>' | tr 'N-ZA-Mn-za-m5-90-4' 'A-Za-z0-9'

ROT47

# Encrypt
echo '<plaintext>' | tr '\!-~' 'P-~\!-O'

# Decrypt
echo '<ciphertext>' | tr 'P-~\!-O' '\!-~'

Caesar

# Encrypt
echo '<plaintext>' | tr '[a-zA-Z]' '[x-za-wX-ZA-W]'

# Decrypt
echo '<ciphertext>' | tr '[x-za-wX-ZA-W]' '[a-zA-Z]'

ROT Script

# ROT script
#!/usr/bin/bash
    
dual=abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
phrase='<plaitext>'
rotat=13
newphrase=$(echo $phrase | tr "${dual:0:26}" "${dual:${rotat}:26}")
echo ${newphrase}

Vigenere

Use vigenere.sh -d to decrypt.

# Vigenere script
#!/usr/local/bin/bash

a="ABCDEFGHIJKLMNOPQRSTUVWXYZ"

[[ "${*/-d/}" != "" ]] &&
echo "Usage: $0 [-d]" && exit 1
m=${1:+-}

printf "string: ";read t
printf "keyphrase: ";read -s k
printf "\n"
for ((i=0;i<${#t};i++)); do
  p1=${a%%${t:$i:1}*}
  p2=${a%%${k:$((i%${#k})):1}*}
  d="${d}${a:$(((${#p1}${m:-+}${#p2})%${#a})):1}"
done
echo "$d"

Encoders

Base64

# Encode
base64 <TEXT>

# Decode
base64 -d <TEXT>

URL

Urlencoder | Urldecoder

# Encode
echo "cat flag.txt" | jq -sRr @uri
hURL -U "cat flag.txt"

# Decode
echo "<urlEncodedString" | python3 -c 'import sys;from urllib.parse import unquote;print(unquote(sys.stdin.read()));'

Hex

# Encode
echo <text> | xxd -p

# Decode
echo <text> | xxd -p -r

Hashes

MD5

md5sum <TEXT>
openssl md5 <TEXT>

SHA256

sha256sum <TEXT>
openssl sha256 <TEXT>

SHA1

sha1sum <TEXT>
openssl sha1 <TEXT>