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< p > < a href = "/files/c/bonuses/05-06.tar.gz" target = "_blank" rel = "noopener noreferrer" > Source< / a > < / p >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "introduction" > Introduction< a href = "#introduction" class = "hash-link" aria-label = "Direct link to Introduction" title = "Direct link to Introduction" > < / a > < / h2 >
< p > In this bonus you will implement few functions that will be used together for
implementing a very special cipher.< / p >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "task-no-1-reverse-05-k" > Task no. 1: Reverse (0.5 K₡)< a href = "#task-no-1-reverse-05-k" class = "hash-link" aria-label = "Direct link to Task no. 1: Reverse (0.5 K₡)" title = "Direct link to Task no. 1: Reverse (0.5 K₡)" > < / a > < / h3 >
< p > Write a function < code > char* reverse(const char* text)< / code > that returns copy of the input
string in reversed order (also uppercase).< / p >
< p > In case you are given < code > NULL< / code > , return < code > NULL< / code > .< / p >
< p > Example (more in tests):< / p >
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< div class = "language-c codeBlockContainer_Ckt0 theme-code-block" style = "--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-c codeBlock_bY9V thin-scrollbar" style = "background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > char< / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > *< / span > < span class = "token plain" > reversed < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > =< / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > reverse< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " Hello world!" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > printf< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " %s\n" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ,< / span > < span class = "token plain" > reversed< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token comment" style = "color:hsl(230, 4%, 64%)" > // " !DLROW OLLEH" < / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > if< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token plain" > reversed < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > !=< / span > < span class = "token plain" > < / span > < span class = "token constant" style = "color:hsl(35, 99%, 36%)" > NULL< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > {< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > free< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token plain" > reversed< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > }< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColo
2023-11-24 16:55:55 +01:00
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "task-no-2-vigenère-05-k" > Task no. 2: Vigenère (0.5 K₡)< a href = "#task-no-2-vigenère-05-k" class = "hash-link" aria-label = "Direct link to Task no. 2: Vigenère (0.5 K₡)" title = "Direct link to Task no. 2: Vigenère (0.5 K₡)" > < / a > < / h3 >
< p > Vigenère cipher is similar to the Caesar cipher, but you also have a key that is
used for encrypting (or decrypting).< / p >
< p > Your task is to write two functions:< / p >
< ul >
< li > < code > char* vigenere_encrypt(const char* key, const char* text)< / code > for encrypting< / li >
< li > < code > char* vigenere_decrypt(const char* key, const char* text)< / code > for decrypting< / li >
< / ul >
< p > In both of those you should return uppercase characters.< / p >
< p > Meaning of the parameters you are given:< / p >
< ul >
< li > < code > key< / code > - String that represents key that is used for *crypting. It consists of
one word and can have only characters of the alphabet. Does not matter if they
are uppercase or lowercase.< / li >
< li > < code > text< / code > - String that is to be *crypted.< / li >
< / ul >
< p > Function returns address of the encrypted (or decrypted) string. Or < code > NULL< / code > in case
error occurs.< / p >
< p > Example:< / p >
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< div class = "language-c codeBlockContainer_Ckt0 theme-code-block" style = "--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-c codeBlock_bY9V thin-scrollbar" style = "background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > char< / span > < span class = "token plain" > < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > *< / span > < span class = "token plain" > encrypted < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > =< / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > vigenere_encrypt< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " CoMPuTeR" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ,< / span > < span class = "token plain" > < / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " Hello world!" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > printf< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " %s\n" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ,< / span > < span class = "token plain" > encrypted< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token comment" style = "color:hsl(230, 4%, 64%)" > // " JSXAI PSINR!" < / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > if< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token plain" > encrypted < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > !=< / span > < span class = "token plain" > < / span > < span class = "token constant" style = "color:hsl(35, 99%, 36%)" > NULL< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > {< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > free< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token plain" > encrypted< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > }< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0 , 0 6 , 7V21A2 , 2 0 0 , 0 8 , 23H
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< h4 class = "anchor anchorWithStickyNavbar_LWe7" id = "bonus-part-05-k" > Bonus part (0.5 K₡)< a href = "#bonus-part-05-k" class = "hash-link" aria-label = "Direct link to Bonus part (0.5 K₡)" title = "Direct link to Bonus part (0.5 K₡)" > < / a > < / h4 >
< p > If you can utilize helper function that would do both encrypting and decrypting,
you can gain 0.5 K₡.< / p >
< p > Usage of < code > true< / code > /< code > false< / code > to decide path in code is prohibited. It leads to merging
of both functions into one. Point of this part is to discover a way to do this
generically in such way that there are no separate paths for one or the other. One
function with no branching for both of them, parametrization is your friend :)< / p >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "task-no-3-bit-madness-05-k" > Task no. 3: Bit madness (0.5 K₡)< a href = "#task-no-3-bit-madness-05-k" class = "hash-link" aria-label = "Direct link to Task no. 3: Bit madness (0.5 K₡)" title = "Direct link to Task no. 3: Bit madness (0.5 K₡)" > < / a > < / h3 >
< p > This is a state of the art crypto. Please do not share :)< / p >
< p > For encrypting:< / p >
< ol >
< li > Split the character that is to be encrypted in halves (4 and 4 bits each).< / li >
< li > Bits in 1st half are to be split into pairs. Swap bits in those pairs.< / li >
< li > Then use the 4 bits that you created in the 2nd step for < code > XOR< / code > with the other
4 bits.< / li >
< / ol >
< p > This simple and ingenious principle will be illustrated on the following example.
String we want to encrypt is < code > Hello world!< / code > . We need to encrypt each letter separately,
so we will demonstrate on letter < code > H< / code > :< / p >
< ol >
< li >
< p > Letter < code > H< / code > is represented in ASCII as < code > 72< / code > .< / p >
< p > < code > 72< / code > represented in binary is: < code > 01001000< / code > . So first 4 bits are: < code > 0100< / code > and last
4 bits are < code > 1000< / code > .< / p >
< / li >
< li >
< p > First half of bits (< code > 0100< / code > ) consists of 2 pairs (< code > 01< / code > and < code > 00< / code > ) which we swap
(< code > 01 ~> 10< / code > and < code > 00 ~> 00< / code > ). That way we get < code > 1000< / code > .< / p >
< / li >
< li >
< p > That half is used for xor with the other 4 bits:< / p >
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< div class = "codeBlockContainer_Ckt0 theme-code-block" style = "--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-text codeBlock_bY9V thin-scrollbar" style = "background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > 1000 // second half< / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > XOR 1000 // first half after 2nd step< / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > --------< / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > 0000< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
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< / li >
< li >
< p > Now we combine both halves (first one is < code > 1000< / code > , which we got from the 2nd step
and second one is < code > 0000< / code > , which we got from the 3rd step) and get < code > 10000000< / code > ,
which is encrypted character < code > H< / code > using this method.< / p >
< / li >
< / ol >
< p > In case of decryption, reverse those steps.< / p >
< p > Your task is to implement functions:< / p >
< ul >
< li > < code > unsigned char* bit_encrypt(const char* text)< / code > < / li >
< li > < code > char* bit_decrypt(const unsigned char* text)< / code > < / li >
< / ul >
< p > Example:< / p >
2024-02-04 13:54:29 +01:00
< div class = "language-c codeBlockContainer_Ckt0 theme-code-block" style = "--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-c codeBlock_bY9V thin-scrollbar" style = "background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > unsigned< / span > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > char< / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > *< / span > < span class = "token plain" > encrypted < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > =< / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > bit_encrypt< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " Hello world!" < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > for< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token keyword" style = "color:hsl(301, 63%, 40%)" > int< / span > < span class = "token plain" > i < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > =< / span > < span class = "token plain" > < / span > < span class = "token number" style = "color:hsl(35, 99%, 36%)" > 0< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > i < / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > < < / span > < span class = "token plain" > < / span > < span class = "token number" style = "color:hsl(35, 99%, 36%)" > 12< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > i< / span > < span class = "token operator" style = "color:hsl(221, 87%, 60%)" > ++< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > {< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token function" style = "color:hsl(221, 87%, 60%)" > printf< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > (< / span > < span class = "token string" style = "color:hsl(119, 34%, 47%)" > " %x " < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ,< / span > < span class = "token plain" > encrypted< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > [< / span > < span class = "token plain" > i< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ]< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > )< / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token comment" style = "color:hsl(230, 4%, 64%)" > //80 9c 95 95 96 11 bc 96 b9 95 9d 10< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:hsl(119, 34%, 47%)" > }< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:hsl(230, 8%, 24%)" > < span class = "token plain" > < / span > <
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< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "task-no-4-all-combined-to-bmp-05-k" > Task no. 4: All combined to BMP (0.5 K₡)< a href = "#task-no-4-all-combined-to-bmp-05-k" class = "hash-link" aria-label = "Direct link to Task no. 4: All combined to BMP (0.5 K₡)" title = "Direct link to Task no. 4: All combined to BMP (0.5 K₡)" > < / a > < / h3 >
< p > Authors of the BMP cipher are non-disclosed :)< / p >
< p > Create pair of functions:< / p >
< ul >
< li > < code > unsigned char* bmp_encrypt(const char* key, const char* text)< / code > < / li >
< li > < code > char* bmp_decrypt(const char* key, const unsigned char* text)< / code > < / li >
< / ul >
< p > BMP cipher consists of following steps for encrypting:< / p >
< ol >
< li > Reverse the input string< / li >
< li > Use Vigenere on the string you got from step #1< / li >
< li > Use bit madness on the string you got from step #2< / li >
< / ol >
< p > For decrypting, reverse the steps.< / p >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "submitting" > Submitting< a href = "#submitting" class = "hash-link" aria-label = "Direct link to Submitting" title = "Direct link to Submitting" > < / a > < / h2 >
< p > In case you have any questions, feel free to reach out to me.< / p >
2024-07-30 22:20:32 +02:00
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< / body >
< / html >
