In this tutorial you will learn about vigenere cipher in C and C for encryption and decryption. Vigenere Cipher is kind of polyalphabetic substitution method. It is used for encryption of alphabetic text. Solidworks 2012 keygen. For encryption and decryption Vigenere Cipher Table is used in which alphabets from A to Z are written in 26 rows.
Also Read: Also Read: Vigenere Cipher Encryption Message Text: THECRAZYPROGRAMMER Key: HELLO Here we have to obtain a new key by repeating the given key till its length become equal to original message length. New Generated Key: HELLOHELLOHELLOHEL For encryption take first letter of message and new key i.e. Take the alphabet in Vigenere Cipher Table where T row and H column coincides i.e. Repeat the same process for all remaining alphabets in message text.
Finally the encrypted message text is: Encrypted Message: ALPNFHDJAFVKCLATIC The algorithm can be expressed in algebraic form as given below. The cipher text can be generated by below equation.
E i = (P i + K i) mod 26 Here P is plain text and K is key. Vigenere Cipher Decryption Encrypted Message: ALPNFHDJAFVKCLATIC Key: HELLO New Generated Key: HELLOHELLOHELLOHEL Take first alphabet of encrypted message and generated key i.e. Analyze Vigenere Cipher Table, look for alphabet A in column H, the corresponding row will be the first alphabet of original message i.e. Repeat the same process for all the alphabets in encrypted message. Original Message: THECRAZYPROGRAMMER Above process can be represented in algebraic form by following equation. P i = (E i – K i + 26) mod 26 We will use above algebraic equations in the program.
Program for Vigenere Cipher in C.
Contents. with Ada. TextIO; procedure VignereCipher is subtype Letter is Character range 'A'.
'Z'; subtype Lowercase is Character range 'a'. 'z'; function '+' (X, Y: Letter ) return Letter is begin return Character'Val ( ( (Character'Pos (X )-Character'Pos ('A' ) ) + (Character'Pos (Y )-Character'Pos ('A' ) ) ) mod 26 + Character'Pos ('A' ) ); end; function Normalize (S: String ) return String is - removes all characters except for uppercase and lowercase letters - replaces lowercase by uppercase letters Offset: Integer:= Character'Pos ('A' ) - Character'Pos ('a' ); begin if S= ' then return '; elsif S (S'First ) in Letter then return S (S'First ) & Normalize (S (S'First+ 1. S'Last ) ); elsif S (S'First ) in Lowercase then return (Character'Val (Character'Pos (S (S'First ) ) + Offset ) & Normalize (S (S'First+ 1.
S'Last ) ) ); else return Normalize (S (S'First+ 1. S'Last ) ); end if; end Normalize; function Encrypt (Key: String; Text: String ) return String is Ciphertext: String (Text' Range ); begin for I in Text' Range loop Ciphertext (I ):= Text (I ) + Key (Key'First + ( (I-Text'First ) mod Key'Length ) ); end loop; return Ciphertext; end Encrypt; function Invert (Key: String ) return String is Result: String (Key' Range ); begin for I in Key' Range loop Result (I ):= Character'Val ( 26 - (Character'Pos (Key (I ) )-Character'Pos ('A' ) ) + Character'Pos ('A' ) ); end loop; return Result; end Invert; use Ada.
TextIO; Input: String:= GetLine; Key: String:= Normalize (GetLine ); Ciph: String:= Encrypt (Key = Key, Text = Normalize (Input ) ); begin PutLine ( 'Input =' & Input ); PutLine ( 'Key =' & Key ); PutLine ( 'Ciphertext =' & Ciph ); PutLine ( 'Decryption =' & Encrypt (Key = Invert (Key ), Text = Ciph ) ); end VignereCipher. Works with: version Any (with appropriate job cards) - tested with release. STRING key:= '; PROC vigenere cipher = ( REF STRING key ) VOID: ( FOR i FROM LWB key TO UPB key DO IF key i = 'A' AND key i = 'a' AND key i = 'a' AND c = 'A' AND c = 'a' AND c = 'A' AND c. Output: Beware the Jabberwock, my son! The jaws that bite, the claws that catch!
Vigenere Cipher Encryption
Encrypted: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH Lines 340,350,430,440 could probably been put into some DEF FN, but it would probably have made it harder to read. The maximum length for a string in AppleSoft BASIC is 255 characters. I have not used the DEF FN MOD(A) function in line 450 on purpose, as I still would have had to correct for a possible negative value.
Output: Input =Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Key =VIGENERECIPHER Ciphertext =WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Decrypted =BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH key$ = 'LEMON' plaintext$ = 'ATTACK AT DAWN' ciphertext$ = FNencrypt(plaintext$, key$) PRINT 'Key = ' key$ ' PRINT 'Plaintext = ' plaintext$ ' PRINT 'Ciphertext = ' ciphertext$ ' PRINT 'Decrypted = ' FNdecrypt(ciphertext$, key$) ' END DEF FNencrypt(plain$, key$) LOCAL i%, k%, n%, o$ plain$ = FNupper(plain$) key$ = FNupper(key$) FOR i% = 1 TO LEN(plain$) n% = ASCMID$(plain$, i%) IF n% = 65 IF n% = 97 IF C%.
Output: Beware the Jabberwock, my son! The jaws that bite, the claws that catch! VIGENERECIPHER Encrypted: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH This doesn't assume anything about character codes other than A-Z being a contiguous block (but still, we could be using EBCDIC. Who knows.) ( defun strip (s ) (remove-if- not ( lambda (c ) (char. Output: msg: Beware the Jabberwock. The jaws that. The claws that catch!
Enc: WMCEEIKLGRPIFVMEUGXXYILILZXYVBZLRGCEYAIOEKXIZGU dec: BEWARETHEJABBERWOCKTHEJAWSTHATTHECLAWSTHATCATCH Requires Clojure 1.2. ( ns org.rosettacode.clojure.vigenere (: require clojure.string: as string ) ); convert letter to offset from A ( defn to -num char ( - (int char ) (int A ) ) ); convert number to letter, treating it as modulo 26 offset from A ( defn from -num num (char ( + (mod num 26 ) (int A ) ) ) ); Convert a string to a sequence of just the letters as uppercase chars ( defn to -normalized -seq str ( map #' first ( re-seq # 'A-Z' (string /upper -case str ) ) ) ); add (op=+) or subtract (op=-) the numerical value of the key letter from the; text letter. Output: Ciphertext: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH USING: arrays ascii formatting kernel math math.functions math.order sequences; IN: rosetta-code.vigenere-cipher: mult-pad ( key input - x ) length 2dup concat dip length keep head dip;: normalize ( str - only-upper-letters ) upper LETTER? filter;: vigenere-encrypt ( key input - ecrypted ) normalize lengthen-pad CHAR: A - map + 26 mod CHAR: A + 2map;: vigenere-decrypt ( key input - decrypted ) normalize lengthen-pad CHAR: A - map - 26 - abs 26 mod CHAR: A + 2map;: main ( - ) 'Vigenere cipher' dup 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch!' 2dup 'Key:%s nInput:%s n' printf vigenere-encrypt dup 'Encrypted:%s n' printf vigenere-decrypt 'Decrypted:%s n' printf; MAIN: main.
Works with: version 95 and later program vigenerecipher implicit none character ( 80 ):: plaintext = 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch!' Translation of: let cipher src key crypt = let str =.uppercase src in let key =.uppercase key in (.
strip out non-letters.) let len =.length str in let rec aux i j = if j = len then.sub str 0 i else if str. j = 'A ' && str. i - d 'A ' + d key. i mod klen - d 'A ' else fun i - d res.
i - d key. i mod klen + 26 in for i = 0 to slen do res. Translation of: A reworking of the version using Open Object Rexx but shouldn't take much to translate to Classic Rexx. /. Rexx./ Do alpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' key = 'LEMON' pt = 'Attack at dawn!' Call test key, pt key = 'N' Call test key, pt key = 'B' Call test key, pt pt = alpha key = 'A' Call test key, pt pt = sampledata ( ) key = 'Hamlet; Prince of Denmark' Call test key, pt Return End Exit vigenere: Procedure Expose alpha Do Parse upper Arg meth, key, text Select When 'ENCIPHER' abbrev (meth, 1 ) = 1 then df = 1 When 'DECIPHER' abbrev (meth, 1 ) = 1 then df = - 1 Otherwise Do Say meth 'invalid. Output: Text: Beware the Jabberwock, my son!
The jaws that bite, the claws that catch! Key: VIGENERECIPHER Code: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Back: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH (de vigenereKey (Str) (extract '((C) (when (= 'Z' (uppc C) 'A') (- (char (uppc C)) 65) ) ) (chop Str) ) ) (de vigenereEncrypt (Str Key) (pack (mapcar '((C K) (char (+ 65 (% (+ C K) 26))) ) (vigenereKey Str) (apply circ (vigenereKey Key)) ) ) ) (de vigenereDecrypt (Str Key) (pack (mapcar '((C K) (char (+ 65 (% (+ 26 (- C K)) 26))) ) (vigenereKey Str) (apply circ (vigenereKey Key)) ) ) ) Test:: (vigenereEncrypt 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch!' 'VIGENERECIPHER' ) - 'WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY': (vigenereDecrypt @ 'VIGENERECIPHER') - 'BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH' cypher: procedure options (main); /. 21 September 2012./ declare t(26) character (26); declare (i, j, k, L) fixed binary; declare (original, encoded, coder) character (1000) varying initial ('); declare cypher character (30) varying; declare (co, ct, cc) character (1); /. Set up cypher table./ t(1) = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; do i = 2 to 26; t(i) = substr(t(i-1), 2, 25) substr(t(i-1), 1, 1); end; cypher = 'VIGILANCE'; original = 'Meet me on Tuesday evening at seven.' ; put edit ('Message=', original) (a); original = uppercase(original); /.
Create the cypher text, same length as original, or longer./ coder = repeat(cypher, length(original)/length(cypher)); /. Encode the original message, character by character./ /. Non-alphabetic characters are ignored./ L = 0; do i = 1 to length(original); co = substr(original, i, 1); j = index(t(1), co); if j = 0 then iterate; /. Ignore non-alphabetic character./ L = L + 1; ct = substr(coder, L, 1); k = index(t(1), ct); encoded = encoded substr(t(j), k, 1); end; put skip data (encoded); /. DECODING./ put skip list ('Decoded='); do i = 1 to length(encoded); cc = substr(coder, i, 1); j = index(t(1), cc); k = index(t(j), substr(encoded, i, 1)); put edit (substr(t(1), k, 1) ) (a(1)); end; end cypher.
Translation of: from itertools import starmap, cycle def encrypt (message, key ): # convert to uppercase. # strip out non-alpha characters. Message = filter ( str. Isalpha, message. Upper ( ) ) # single letter encrpytion. Def enc (c,k ): return chr ( ( ( ord (k ) + ord (c ) - 2.
ord ( 'A' ) )% 26 ) + ord ( 'A' ) ) return '. Join (starmap (enc, zip (message, cycle (key ) ) ) ) def decrypt (message, key ): # single letter decryption. Def dec (c,k ): return chr ( ( ( ord (c ) - ord (k ) - 2. ord ( 'A' ) )% 26 ) + ord ( 'A' ) ) return '. Join (starmap (dec, zip (message, cycle (key ) ) ) ) Demonstrating: text = 'Beware the Jabberwock, my son!
The jaws that bite, the claws that catch!' Key = 'VIGENERECIPHER' encr = encrypt (text, key ) decr = decrypt (encr, key ) print text print encr print decr. Works with: prep:= : s s select: : ch ch isLetter thenCollect: : ch ch asUppercase. Encrypt:= : s: cypher ( prep value: s ) keysAndValuesCollect: : i: ch ch rot: ( ( cypher at: ( ( i- 1 ) key size+ 1 ) )-$ A ). Decrypt:= : s: cypher ( prep value: s ) keysAndValuesCollect: : i: ch ch rot: 26- ( ( cypher at: ( ( i- 1 ) key size+ 1 ) )-$ A ). Test: plain:= 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch!'
Cypher:= 'VIGENERECIPHER'. Crypted:= encrypt value: plain value: cypher.
Plain2:= decrypt value: crypted value: cypher. Crypted - 'WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY' plain2 - 'BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH'. Output: Beware the Jabberwock, my son! The jaws that bite, the claws that catch!
Key = vigenerecipher Encrypted: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH The KEYWORD must be UPPERCASE. Precede it with a minus sign to decrypt a file. Usage: vigenere KEYWORD outfile.xxx code ChIn=7, ChOut=8; int Neg, C, Len, I, Key; char KeyWord(80); Neg:= false; skip to KEYWORD repeat C:= ChIn(8); if C=^- then Neg:= true; until C=^A & C^Z; I:= 0; initialize cycling index repeat C:= ChIn(1); if C=^a & C=^A & C=Len then I:= 0; if Neg then Key:= -Key; decrypting? C:= C+Key; if C^Z then C:= C-26 else if C.
Earlier we talked about and its implementation both in C and C, it was a kind of encryption where each letter was replaced by a letter corresponding to a certain number of alphabets after or before it. Vigenere Cipher is a way of encryption where different series of were used. In simple words it was a type of poly-alphabetical encryption where a key decided by the person who encrypted the text, was used for decryption. It also applied that a same alphabet in the same string can have a different code alphabet which made the decryption more and more complex.
Talking about the table which was used for encryption and decryption was basically a kind of mapping table. So Looking at this table I ll give you an Example. Just suppose 'RAKSHIT' was to be encrypted and the key decided was 'KEY' So the key decided was written below the string this way: Now Each alphabet was mapped so as to get the encrypted alphabet.
For Example R would be written as B when we consider the top row as out string and column as the key and so on for the rest of the string. And so RAKSHIT would be encrypted as BEICLGD. Now converting into computer logic i came across 2 formulas: For Encryption E 1 = (S 1 + K 1)% 26 (% means remainder) For Decryption D 1 = (E 1 - K 1 + 26)% 26 (% means remainder).
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