#Input string
msg = "I wonder if this code can be better."
#Randomly-generated key
key = "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23"
#This is the only way I can figure out how to store the result of the .each loops
ciphered = ""
deciphered = ""
beg = 32 #Equivalent to ASCII's {space} in decimal
fin = 91 #Equivalent to the distance between ASCII {space} and ASCII {z}
(0..msg.length-1).each do |i|
foo = (msg[i] - beg) + (key[i] - beg)
foo %= fin if foo > fin
foo += beg
ciphered << foo
end
(0..msg.length-1).each do |i|
foo = (ciphered[i] - beg) - (key[i] - beg)
foo += fin if foo < 0
foo += beg
deciphered << foo
end
#msg should now be the same as deciphered
puts msg
puts ciphered
puts deciphered
Refactorings
No refactoring yet !
amoeba.myopenid.com
November 6, 2007, November 06, 2007 03:31, permalink
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Some optimizations.
+Use of .times method
+Simplified math
msg = "I wonder if this code can be better." key = "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23" ciphered = "" deciphered = "" beg = 32 fin = 91 msg.length.times do |i| foo = msg[i] + key[i] - 2 * beg foo %= fin if foo > fin foo += beg ciphered << foo end msg.length.times do |i| foo = ciphered[i] - key[i] foo += fin if foo < 0 foo += beg deciphered << foo end puts msg puts ciphered puts deciphered
amoeba.myopenid.com
November 6, 2007, November 06, 2007 03:40, permalink
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Wow.
msg = "I wonder if this code can be better." key = "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23" ciphered = "" deciphered = "" offset = 32 range = 91 msg.length.times do |i| ciphered << (msg[i] + key[i] - 2*offset) % range + offset end msg.length.times do |i| deciphered << (ciphered[i] - key[i]) % range + offset end puts msg puts ciphered puts deciphered
rpheath
November 6, 2007, November 06, 2007 23:16, permalink
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Maybe I'm not thinking clearly, but why are there two separate loops? Couldn't that be combined?
msg = "I wonder if this code can be better." key = "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23" ciphered, deciphered = "", "" offset, range = 32, 91 msg.length.times do |i| ciphered << (msg[i] + key[i] - 2*offset) % range + offset deciphered << (ciphered[i] - key[i]) % range + offset end puts msg puts ciphered puts deciphered
Jason Dew
November 7, 2007, November 07, 2007 03:46, permalink
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this code will be much cleaner in Ruby 1.9 when we get external iterators.... but, i formed the code into a class, cleaned up the math a bit, and made the cipher reuse the key if the string to be encoded/decoded is longer than the key. i also added a very simple spec (using RSpec)
class Cipher
Offset = ?\ # ascii value of a space
Range = ?z - ?\ # difference between ascii values for z and space
def initialize(key)
@key = key
@key_length = key.size
end
def encode( clear_text )
cipher_text = String.new
index = 0
clear_text.each_byte do |byte|
cipher_text << (byte + @key[index % @key_length] - 2*Offset) % Range + Offset
index += 1
end
cipher_text
end
def decode( cipher_text )
clear_text = String.new
index = 0;
cipher_text.each_byte do |byte|
clear_text << (byte - @key[index % @key_length] + Range) % Range + Offset
index += 1
end
clear_text
end
end
require 'cipher'
describe Cipher, "with a sufficient key size" do
before do
@cipher = Cipher.new( "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23" )
end
it "should correctly encode a string" do
@cipher.encode( "I wonder if this code can be better." ).should == 'B7bD\Qw^qV<RQFci3s(,!7xv%Gwep-dB_"0%'
end
it "should correctly decode a string" do
@cipher.decode( 'B7bD\Qw^qV<RQFci3s(,!7xv%Gwep-dB_"0%' ).should == "I wonder if this code can be better."
end
end
describe Cipher, "without a sufficient key size" do
before do
@cipher = Cipher.new( "s3EHqP9f23" )
end
it "should correctly encode a string" do
@cipher.encode( "I wonder if this code can be better." ).should == "B3B=e:$^2\"_3?6`I9O'w^3./eP!Q2u^-?3i^"
end
it "should correctly decode a string" do
@cipher.decode( "B3B=e:$^2\"_3?6`I9O'w^3./eP!Q2u^-?3i^" ).should == "I wonder if this code can be better."
end
end
Sam
November 10, 2007, November 10, 2007 01:28, permalink
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getting rid of 'ciphered, deciphered = "", ""'
msg = "I wonder if this code can be better." key = "s7eOhg2fqgPRWXtp303B67551G5zpEyHe78q5NR5eWKP9eq9fk54D23" offset, range = 32, 91 msg.length.times do |i| (ciphered = '') << (msg[i] + key[i] - 2*offset) % range + offset (deciphered = '') << (ciphered[i] - key[i]) % range + offset end puts msg puts ciphered puts deciphered
Simple cipher program. Modifies an initial message by some key, using their ASCII values to perform the math.
Intended to be easily converted to other programming languages.
Input can contain A-z, numbers, apostrophes and spaces (and nothing else).
Ciphered text needs to be sent via HTTP GET request (i.e. http://mysite.com/#{ciphered})