52 lines
1.1 KiB
C++
52 lines
1.1 KiB
C++
|
|
#include "codec_vigenere.hh"
|
|
|
|
namespace LibCryptAffinity {
|
|
CodecVigenere::CodecVigenere() : Codec() {
|
|
}
|
|
|
|
Text CodecVigenere::decode(Text t, KeyVigenere k){
|
|
Text result = t;
|
|
int txt_idx;
|
|
int key_idx;
|
|
int i;
|
|
int alpha_size = t.getAlphabet().size();
|
|
for (txt_idx=0; txt_idx<t.size(); txt_idx+=k.size()){
|
|
for (key_idx = 0; key_idx < k.size(); key_idx++) {
|
|
i = txt_idx + key_idx;
|
|
if (i < t.size()){
|
|
int cypher = result[i];
|
|
int key = k[key_idx];
|
|
int plain = (cypher + alpha_size - key) % (alpha_size);
|
|
result[i] = plain;
|
|
}
|
|
}
|
|
|
|
}
|
|
return result;
|
|
}
|
|
|
|
Text CodecVigenere::encode(Text t, KeyVigenere k){
|
|
Text result;
|
|
int txt_idx;
|
|
int key_idx;
|
|
int i;
|
|
int alpha_size = t.getAlphabet().size();
|
|
for (txt_idx=0; txt_idx<t.size(); txt_idx+=k.size()){
|
|
for (key_idx = 0; key_idx < k.size(); key_idx++) {
|
|
i = txt_idx + key_idx;
|
|
if (i < t.size()){
|
|
int plain = result[i];
|
|
int key = k[key_idx];
|
|
int cypher = (plain + key) % (alpha_size);
|
|
result[i] = cypher;
|
|
|
|
}
|
|
}
|
|
|
|
}
|
|
return result;
|
|
}
|
|
|
|
}
|