README
¶
caesar
a classic cipher cli
Installation
$ go install github.com/stripedpajamas/caesar/cmd/...
$ caesar help
generally the syntax is
caesar -c <cipher> -k <key> -t <text> <encrypt|decrypt>
leave off -t <text> and caesar will read from stdin.
optionally you can also provide a --groups or -g parameter to specify how the output should be grouped. the default value is 5. groups setting is ignored for decrypt operations.
# encrypting using caesar cipher
$ caesar -c caesar -k m -t "peter" encrypt
BQFQD
$ caesar -c caesar -k m -t "BQFQD" decrypt
PETER
ciphers implemented:
- caesar https://en.wikipedia.org/wiki/Caesar_cipher
- playfair https://en.wikipedia.org/wiki/Playfair_cipher
- vigenere https://en.wikipedia.org/wiki/Vigenère_cipher
- ADFGX https://en.wikipedia.org/wiki/ADFGVX_cipher (ADFGVX is not implemented)
- Bifid https://en.wikipedia.org/wiki/Bifid_cipher
generally all the ciphers operate on english alphabetic letters (a-z). plaintext and keys are both specified as letters (although a number works for the caesar cipher as well, see below).
Using Different Ciphers
Caesar
- encryption removes all non-alphabetic characters (encrypting
abc123== encryptingabc) - the key can be a letter or a number
- the letter x is interpreted as a = x for the shift
- the number n is interpreted as shift the alphabet n places. concretely, this means keys a, b, c, ... are equivalent to keys 0, 1, 2, ....
- any number provided is wrapped around mod 26
- if a multi-letter key is provided, all but the first letter is ignored
- example:
$ caesar -c caesar -k m -t "peter" encrypt BQFQD $ caesar -c caesar -k m -t "BQFQD" decrypt PETER
Playfair
- encryption removes all non-alphabetic characters (encrypting "abc123" == encrypting "abc")
- the key should be a keyword (anything else would be equivalent encrypting without a key)
jis merged withi, so decrypting an encryption of "Joel" will result in "Ioel"- odd-length plaintext and double-letters are padded with
X, unless the double letter is anX, then it is padded withQ - example:
$ caesar -c playfair -k secret -t "peter" encrypt OCSCC Y $ caesar -c playfair -k secret -t "OCSCCY" decrypt PETERX
Vigenère
- encryption removes all non-alphabetic characters (encrypting "abc123" == encrypting "abc")
- non-alphabetic characters are ignored if present in the key
- an empty key will return an error
- example:
$ caesar -c vigenere -k hotsauce -t "let's eat some cheerios" encrypt SSMKE UVWVA XUHYG VPCL $ caesar -c vigenere -k hotsauce -t "SSM KEU VWV AXU HYG VPC L" decrypt LETSEATSOMECHEERIOS
ADFGX
- encryption removes all non-alphabetic characters (encrypting "abc123" == encrypting "abc")
- this is not ADFGVX, so numbers are no supported
- two keys are required for this cipher, one for the polybius square and one for the transposition step
- the keys should be comma delimited when running (e.g.
-k keyOne,keyTwo)
- the keys should be comma delimited when running (e.g.
- non-alphabetic characters are ignored if present in either key
- if either key is empty, it will return an error
- example:
$ caesar -c adfgx -k help,me -t "this is a test" encrypt GAAFA FXGDF GGAFG FGAGA GG $ caesar -c adfgx -k help,me -t "GAAFA FXGDF GGAFG FGAGA GG" decrypt THISISATEST
Bifid
- encryption removes all non-alphabetic characters (encrypting "abc123" == encrypting "abc")
- non-alphabetic characters are ignored if present in either key
- example:
$ caesar -c bifid -k golden -t spandex encrypt SAGXW DX $ caesar -c bifid -k golden -t sagxwdx decrypt SPANDEX
Other options
- group output in chunks
$ caesar -g 10 -c caesar -k m -t "mary had a little lamb whose fleece was white as snow" encrypt YMDKTMPMXU FFXQXMYNIT AEQRXQQOQI MEITUFQMEE ZAI - read from stdin
$ cat my_love_letter.txt | caesar -c caesar -k 5 encrypt NKDTZ WJWJF INSLY MNXYM FYXUW JYYDH TTQ - chaining (careful when chaining ciphers that use a polybius square with ciphers that don't, as the I/J situation can get wonky)
$ echo "potatoes or potatos" | caesar -c caesar -k 7 e | caesar -c vigenere -k "poptarts" e LJPAA MERKM LOAYT NO $ echo "LJPAA MERKM LOAYT NO" | caesar -c vigenere -k "poptarts" d | caesar -c caesar -k 7 d POTATOESORPOTATOS
License
MIT
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ADFGX ¶
type ADFGX struct{}
ADFGX represents the ADFGX cipher and conforms to the Cipher interface https://en.wikipedia.org/wiki/ADFGVX_cipher
func (ADFGX) Decrypt ¶
Decrypt operates on a ciphertext string and a key string that consists of two keys delimited by a semicolon (,). The function first transposes the letters according to key2, and then undoes the substitution using an alphabet square and key1.
func (ADFGX) Encrypt ¶
Encrypt operates on a plaintext string and a key string that consists of two keys delimited by a semicolon (,). The function constructs an alphabet square from key 1, and obtains substitution values from it. Then key 2 is used to transpose the values into the finished ciphertext.
type Bifid ¶
type Bifid struct{}
Bifid represents the Bifid cipher and conforms to the Cipher interface https://en.wikipedia.org/wiki/Bifid_cipher
func (Bifid) Decrypt ¶
Decrypt operates on a ciphertext string and a key string The function constructs and alphabet square from the key, and obtains substitution values from it. The substitution values are de-transposed into values that are looked up in the square to obtain the original plaintext string.
type Caesar ¶
type Caesar struct{}
Caesar represents the classic Caesar cipher and conforms to the Cipher interface https://en.wikipedia.org/wiki/Caesar_cipher
type Cipher ¶
type Cipher interface {
Encrypt(string, string) (string, error)
Decrypt(string, string) (string, error)
}
Cipher represents an old school cipher with encryption and decryption methods that operate on ASCII inputs and keys
type Playfair ¶
type Playfair struct{}
Playfair represents the Playfair cipher and conforms to the Cipher interface https://en.wikipedia.org/wiki/Playfair_cipher
type Vigenere ¶
type Vigenere struct{}
Vigenere represents the polyalphabetic substitution Vigenere cipher and conforms to the Cipher interface https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
Source Files
Directories