***DAILY CHALLENGE***: this one is about encryption & decryption. sounds complicated?!? Not this one ;)

Question

TASK:
write a function that get as input an ecnrypted text and a key (both strings) and outputs the decrypted text!
input text: "#mpdgpuefzouquyyxzv#|#ypkerrzcovchvgjuwp#"
let the program calculate and print the ouput. The '#' and '|' symbolize beginnig and end of string (don't use them in decryption)!!!

EXTRA:
use these functions to get the int value for a character (and vice versa):
s = " abcdefghijklmnopqrstuvwxyz"
function get_int(c):
i = 0
while i < s.length():
if s[i] == c:
return i
print("ERROR")
return -1
function get_char(i):
while i < 0:
i += s.length()
i %= s.length()
return s[i]
############################################

INFO: (you need to use One-Time-Pad & Cesar-Cipher)
the key is encrypted the following way: msg = "hi"
1) OTP encryption (create a string size of msg. loop over key and msg and add their int values)
random key = "zf" = 26 6, msg = "hi" = 8 9
--> encrypted text is: 26+8 6+9 = 34 15 = "go" ( = 7 15)
2) CESAR encryption (add to each int value (from char) the length of the key) only on key!
key = "go" = 7 15
--> encrypted key is: 7+2 5+2 = 9 7 = "ig"
now ouput is allways as follows: #key#|#txt#
result: -----> "#ig#|#go#" (and 'nobody' knows what that means ^^)

YOUR PART IS TO GO THE SAME WAY BACKWARDS MEANING:
redo the cesar_cipher(- key.length)
then redo the otp encryption by using get_char(key - encrypted)
for all chars in key and encrypted

Hope explanation is understandable ...
if not check out my implementation:
https://code.sololearn.com/cgq1RmKzNmlN/#py

GOOD LUCK CODERS!!!

If this one is too complicated try another one:
-- will be uploaded soon --

Answer 1

https://code.sololearn.com/cMaS4FBo84lP/#cs

That was kinda easy.

Answer 2

@aziz solves this issue with a perfect algorithm
https://code.sololearn.com/cSIH9XiW6Hhz/?ref=app

Answer 3

ok imagine the following situation:
-my input is:
msg = "hello"
-now i create a random string with same length:
key = "abdfs"
-convert each character from msg and key into numbers
msg = "hello" = [8,5,12,12,15]
key = "abdfh" = [1,2,4,6,8]
-now add each number
sum = [9,7,16,18,32]
-convert the numbers back to characters:
encrypted = "igprf"

decrypting is the same but now you subtract each number from key - each number from encrypted text
(THIS IS YOUR PART)

Answer 4

@Vari it's a cesar encryp, k=2

Answer 5

@@ julian
there is a bug in your post...(not in code; in post)
u took
a=1 up to z=26
so g is 7 of course
now in your example
it came up 34-15
u changed it 7-15
why????????
SHOULD NOT IT BE 8-15
(34-26)=8
so it wont be" go" it will be "ho"

Answer 6

N.B This works on PC only.
https://code.sololearn.com/c1X7r71oO4Ua/?ref=app

Answer 7

Sounds like a good challenge though I think I'll pass. My phone can only do so much 😂

Answer 8

https://code.sololearn.com/cl2tPFy81t3G/?ref=app

Answer 9

My site is encrypted
https://code.sololearn.com/WF13NaXMd1vO/?ref=app

Answer 10

This was written before the challenge so it's mostly FYI:
https://code.sololearn.com/W85GKwfubQ6Z/?ref=app

The demo analyzes the ciphertext, guesses the key and decrypts the first part of Alice in Wonderland.
...or you can paste this at line 17 (it should look familiar):

var sampleText="TQYBO SXQBBUDWU: jxyi edu yi qrekj udshofjyed & tushofjyed. iekdti secfbysqjut?!? Dej jxyi edu ... OEKH FQHJ YI JE WE JXU IQCU MQO RQSAMQHTI CUQDYDW: hute jxu suiqh_syfxuh(- auo.budwjx) jxud hute jxu ejf udshofjyed ro kiydw wuj_sxqh(auo - udshofjut) veh qbb sxqhi yd auo qdt udshofjut Xefu unfbqdqjyed yi kdtuhijqdtqrbu ... yv dej sxusa ekj co ycfbucudjqjyed WEET BKSA SETUHI!!! Yv jxyi edu yi jee secfbysqjut jho qdejxuh edu mybb ru kfbeqtut ieed";

Answer 11

#include <stdio.h>
#include <ctype.h>
#define MAXSIZE 1024
void encrypt(char*);
void decrypt(char*);
int menu();
int main(void) { char c, choice[2], s[MAXSIZE]; while(1) { menu(); gets(choice); if((choice[0]=='e')||(choice[0]=='E')) { puts("Input text to encrypt->"); gets(s); encrypt(s); } else if((choice[0]=='d')||(choice[0]=='D')) { puts("Input text to decrypt->"); gets(s); decrypt(s); } else break; } return 0; } void encrypt(char*str) { int n=0; char *p=str, q[MAXSIZE]; while(*p) { if(islower(*p)) { if((*p>='a')&&(*p<'x')) q[n]=toupper(*p + (char)3); else if(*p=='x') q[n]='A'; else if(*p=='y') q[n]='B'; else q[n]='C'; } else { q[n]=*p; } n++; p++; } q[n++]='\0'; puts(q); } void decrypt(char*str) { int n=0; char *p=str, q[MAXSIZE]; while(*p) { if(isupper(*p)) { if((*p>='D')&&(*p<='Z')) q[n]=tolower(*p - (char)3); else if(*p=='A') q[n]='x'; else if(*p=='B') q[n]='y'; else q[n]='z'; } else { q[n]=*p; } n++; p++; } q[n++]='\0'; puts(q); } int menu() { puts("To encrypt, input e or E\n"); puts("To decrypt, input d or D\n"); puts("To exit, input any other letter\n"); puts("Your choice:->\n"); return 0; }

Answer 12

Public static void main (String[]args){
system.out.println("Java has ruined my life");
}

Answer 13

HEY PEOPLE OUT THERE. I'M BACK FROM VACATION.
AND ANOTHER DAY MEANS ANOTHER CHALLENGE. CHECK IT OUT!!!

https://www.sololearn.com/discuss/622449/?ref=app

SOLUTION WILL BE UPLOADED TOMORROW NIGHT!

Answer 14

https://code.sololearn.com/WR6mrmI4KsuK/?ref=app

Answer 15

My progress so far https://code.sololearn.com/cbxTOxwBapKa/?ref=app

Answer 16

This is my code ,, I try to make it simple
https://code.sololearn.com/c2Ov4DE0jpE0/?ref=app

Answer 17

WOW ... THANK'S TO YOU ALL FOR COTD!!! :)

Answer 18

Rather crude way of doing it https://code.sololearn.com/cbxTOxwBapKa/?ref=app

Answer 19

here's my try in Python
https://code.sololearn.com/cVfgGi82JzYC/?ref=app

Answer 20

last week it was around midnight. I decided to write a program that could encrypt any text and I wrote half of it but when I woke up the next morning I didn't understand anything of the code that I wrote the day before that was how I didn't created an encryption program 😅😅😅