47 lines
1.6 KiB
Markdown
47 lines
1.6 KiB
Markdown
|
# Atbash Cipher
|
||
|
|
|
||
|
|
Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
|
||
|
|
|
||
|
|
The Atbash cipher is a simple substitution cipher that relies on
|
||
|
|
transposing all the letters in the alphabet such that the resulting
|
||
|
|
alphabet is backwards. The first letter is replaced with the last
|
||
|
|
letter, the second with the second-last, and so on.
|
||
|
|
|
||
|
|
An Atbash cipher for the Latin alphabet would be as follows:
|
||
|
|
|
||
|
|
```plain
|
||
|
|
Plain: abcdefghijklmnopqrstuvwxyz
|
||
|
|
Cipher: zyxwvutsrqponmlkjihgfedcba
|
||
|
|
```
|
||
|
|
|
||
|
|
It is a very weak cipher because it only has one possible key, and it is
|
||
|
|
a simple monoalphabetic substitution cipher. However, this may not have
|
||
|
|
been an issue in the cipher's time.
|
||
|
|
|
||
|
|
Ciphertext is written out in groups of fixed length, the traditional group size
|
||
|
|
being 5 letters, and punctuation is excluded. This is to make it harder to guess
|
||
|
|
things based on word boundaries.
|
||
|
|
|
||
|
|
## Examples
|
||
|
|
- Encoding `test` gives `gvhg`
|
||
|
|
- Decoding `gvhg` gives `test`
|
||
|
|
- Decoding `gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt` gives `The quick brown fox jumps over the lazy dog.`
|
||
|
|
|
||
|
|
To run the tests simply run the command `go test` in the exercise directory.
|
||
|
|
|
||
|
|
If the test suite contains benchmarks, you can run these with the `-bench`
|
||
|
|
flag:
|
||
|
|
|
||
|
|
go test -bench .
|
||
|
|
|
||
|
|
For more detailed info about the Go track see the [help
|
||
|
|
page](http://exercism.io/languages/go).
|
||
|
|
|
||
|
|
## Source
|
||
|
|
|
||
|
|
Wikipedia [http://en.wikipedia.org/wiki/Atbash](http://en.wikipedia.org/wiki/Atbash)
|
||
|
|
|
||
|
|
## Submitting Incomplete Problems
|
||
|
|
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
|
||
|
|
|