commit 70ee4ecf0f2cf358417289c00aa36ed940d96870
parent d98a156332d4986e49d4e49fcc9de831bb497091
Author: Andrew Laack <andrew@laack.co>
Date: Sat, 11 Oct 2025 22:22:17 -0500
Basic shift cipher for alpha num in c
Diffstat:
4 files changed, 361 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -1 +1,2 @@
*.out
+*artifacts*
diff --git a/crypto/Makefile b/crypto/Makefile
@@ -0,0 +1,10 @@
+clean:
+ rm -rf artifacts
+shift-cipher: clean
+ tcc shift-cipher.c -o shift.out
+test-shift-cipher: shift-cipher
+ mkdir artifacts
+ ./shift.out test-files/ascii.txt artifacts/ascii-encrypted.txt 200
+ ./shift.out artifacts/ascii-encrypted.txt artifacts/ascii.txt -200
+ sha256sum artifacts/ascii.txt test-files/ascii.txt
+ # Do the checksums match? This tests that invariant
diff --git a/crypto/shift-cipher.c b/crypto/shift-cipher.c
@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+char rotate(char in, int rotateBy){
+ char result = in;
+
+ if( islower(in) ){
+ char offset = in - 'a';
+ int res = offset + rotateBy;
+ while(res < 0){
+ res += 26;
+ }
+ result = ((res) % 26) + 'a';
+ }
+ else if( isupper(in) ){
+ char offset = in - 'A';
+ if(offset < 0){
+ offset += 26;
+ }
+ int res = offset + rotateBy;
+ while(res < 0){
+ res += 26;
+ }
+ result = ((res) % 26) + 'A';
+
+ }
+ else if (isalnum(in)){
+ char offset = in - '0';
+ if(offset < 0){
+ offset += 10;
+ }
+ int res = offset + rotateBy;
+ while(res < 0){
+ res += 10;
+ }
+ result = ((res) % 10) + '0';
+ }
+
+ return result;
+}
+
+int main(int argc, char *argv[]){
+
+ int opt;
+
+
+
+ if (argc < 4){
+ printf("Usage: shift {input_file} {output_file} {rotate_by}\n");
+ return -1;
+ }
+
+ char* inputFileName;
+ inputFileName = argv[1];
+
+ char* outputFileName;
+ outputFileName = argv[2];
+
+
+ int rotateBy = atoi(argv[3]);
+
+ FILE *fptr = fopen(inputFileName, "r");
+
+ if (fptr == NULL){
+ printf("Bad input file. \n");
+ return -1;
+ }
+
+ FILE *outPtr = fopen(outputFileName, "w");
+
+ int readIn = 100;
+ char next[readIn];
+ char nextCipher[readIn];
+
+ while(fgets(next, readIn, fptr)){
+ for (int itr = 0; next[itr] != 0; ++itr){
+ nextCipher[itr] = rotate(next[itr], rotateBy);
+ fputc(nextCipher[itr], outPtr);
+ }
+ }
+
+ fclose(fptr);
+ fclose(outPtr);
+}
diff --git a/crypto/test-files/ascii.txt b/crypto/test-files/ascii.txt
@@ -0,0 +1,264 @@
+
+ASCII control characters non printable :
+
+ASCII code 00 = NULL ( Null character )
+ASCII code 01 = SOH ( Start of Header )
+ASCII code 02 = STX ( Start of Text )
+ASCII code 03 = ETX ( End of Text, hearts card suit )
+ASCII code 04 = EOT ( End of Transmission, diamonds card suit )
+ASCII code 05 = ENQ ( Enquiry, clubs card suit )
+ASCII code 06 = ACK ( Acknowledgement, spade card suit )
+ASCII code 07 = BEL ( Bell )
+ASCII code 08 = BS ( Backspace )
+ASCII code 09 = HT ( Horizontal Tab )
+ASCII code 10 = LF ( Line feed )
+ASCII code 11 = VT ( Vertical Tab, male symbol, symbol for Mars )
+ASCII code 12 = FF ( Form feed, female symbol, symbol for Venus )
+ASCII code 13 = CR ( Carriage return )
+ASCII code 14 = SO ( Shift Out )
+ASCII code 15 = SI ( Shift In )
+ASCII code 16 = DLE ( Data link escape )
+ASCII code 17 = DC1 ( Device control 1 )
+ASCII code 18 = DC2 ( Device control 2 )
+ASCII code 19 = DC3 ( Device control 3 )
+ASCII code 20 = DC4 ( Device control 4 )
+ASCII code 21 = NAK ( NAK Negative-acknowledge )
+ASCII code 22 = SYN ( Synchronous idle )
+ASCII code 23 = ETB ( End of trans. block )
+ASCII code 24 = CAN ( Cancel )
+ASCII code 25 = EM ( End of medium )
+ASCII code 26 = SUB ( Substitute )
+ASCII code 27 = ESC ( Escape )
+ASCII code 28 = FS ( File separator )
+ASCII code 29 = GS ( Group separator )
+ASCII code 30 = RS ( Record separator )
+ASCII code 31 = US ( Unit separator )
+ASCII code 127 = DEL ( Delete )
+Printable ASCII characters :
+( alphanumeric, symbols and signs )
+
+ASCII code 32 = space ( Space )
+ASCII code 33 = ! ( Exclamation mark )
+ASCII code 34 = " ( Double quotes ; Quotation mark ; speech marks )
+ASCII code 35 = # ( Number sign )
+ASCII code 36 = $ ( Dollar sign )
+ASCII code 37 = % ( Percent sign )
+ASCII code 38 = & ( Ampersand )
+ASCII code 39 = ' ( Single quote or Apostrophe )
+ASCII code 40 = ( ( round brackets or parentheses, opening round bracket )
+ASCII code 41 = ) ( parentheses or round brackets, closing parentheses )
+ASCII code 42 = * ( Asterisk )
+ASCII code 43 = + ( Plus sign )
+ASCII code 44 = , ( Comma )
+ASCII code 45 = - ( Hyphen , minus sign )
+ASCII code 46 = . ( Dot, full stop )
+ASCII code 47 = / ( Slash , forward slash , fraction bar , division slash )
+ASCII code 48 = 0 ( number zero )
+ASCII code 49 = 1 ( number one )
+ASCII code 50 = 2 ( number two )
+ASCII code 51 = 3 ( number three )
+ASCII code 52 = 4 ( number four )
+ASCII code 53 = 5 ( number five )
+ASCII code 54 = 6 ( number six )
+ASCII code 55 = 7 ( number seven )
+ASCII code 56 = 8 ( number eight )
+ASCII code 57 = 9 ( number nine )
+ASCII code 58 = : ( Colon )
+ASCII code 59 = ; ( Semicolon )
+ASCII code 60 = < ( Less-than sign )
+ASCII code 61 = = ( Equals sign )
+ASCII code 62 = > ( Greater-than sign ; Inequality )
+ASCII code 63 = ? ( Question mark )
+ASCII code 64 = @ ( At sign )
+ASCII code 65 = A ( Capital letter A )
+ASCII code 66 = B ( Capital letter B )
+ASCII code 67 = C ( Capital letter C )
+ASCII code 68 = D ( Capital letter D )
+ASCII code 69 = E ( Capital letter E )
+ASCII code 70 = F ( Capital letter F )
+ASCII code 71 = G ( Capital letter G )
+ASCII code 72 = H ( Capital letter H )
+ASCII code 73 = I ( Capital letter I )
+ASCII code 74 = J ( Capital letter J )
+ASCII code 75 = K ( Capital letter K )
+ASCII code 76 = L ( Capital letter L )
+ASCII code 77 = M ( Capital letter M )
+ASCII code 78 = N ( Capital letter N )
+ASCII code 79 = O ( Capital letter O )
+ASCII code 80 = P ( Capital letter P )
+ASCII code 81 = Q ( Capital letter Q )
+ASCII code 82 = R ( Capital letter R )
+ASCII code 83 = S ( Capital letter S )
+ASCII code 84 = T ( Capital letter T )
+ASCII code 85 = U ( Capital letter U )
+ASCII code 86 = V ( Capital letter V )
+ASCII code 87 = W ( Capital letter W )
+ASCII code 88 = X ( Capital letter X )
+ASCII code 89 = Y ( Capital letter Y )
+ASCII code 90 = Z ( Capital letter Z )
+ASCII code 91 = [ ( square brackets or box brackets, opening bracket )
+ASCII code 92 = \ ( Backslash , reverse slash )
+ASCII code 93 = ] ( box brackets or square brackets, closing bracket )
+ASCII code 94 = ^ ( Circumflex accent or Caret )
+ASCII code 95 = _ ( underscore , understrike , underbar or low line )
+ASCII code 96 = ` ( Grave accent )
+ASCII code 97 = a ( Lowercase letter a , minuscule a )
+ASCII code 98 = b ( Lowercase letter b , minuscule b )
+ASCII code 99 = c ( Lowercase letter c , minuscule c )
+ASCII code 100 = d ( Lowercase letter d , minuscule d )
+ASCII code 101 = e ( Lowercase letter e , minuscule e )
+ASCII code 102 = f ( Lowercase letter f , minuscule f )
+ASCII code 103 = g ( Lowercase letter g , minuscule g )
+ASCII code 104 = h ( Lowercase letter h , minuscule h )
+ASCII code 105 = i ( Lowercase letter i , minuscule i )
+ASCII code 106 = j ( Lowercase letter j , minuscule j )
+ASCII code 107 = k ( Lowercase letter k , minuscule k )
+ASCII code 108 = l ( Lowercase letter l , minuscule l )
+ASCII code 109 = m ( Lowercase letter m , minuscule m )
+ASCII code 110 = n ( Lowercase letter n , minuscule n )
+ASCII code 111 = o ( Lowercase letter o , minuscule o )
+ASCII code 112 = p ( Lowercase letter p , minuscule p )
+ASCII code 113 = q ( Lowercase letter q , minuscule q )
+ASCII code 114 = r ( Lowercase letter r , minuscule r )
+ASCII code 115 = s ( Lowercase letter s , minuscule s )
+ASCII code 116 = t ( Lowercase letter t , minuscule t )
+ASCII code 117 = u ( Lowercase letter u , minuscule u )
+ASCII code 118 = v ( Lowercase letter v , minuscule v )
+ASCII code 119 = w ( Lowercase letter w , minuscule w )
+ASCII code 120 = x ( Lowercase letter x , minuscule x )
+ASCII code 121 = y ( Lowercase letter y , minuscule y )
+ASCII code 122 = z ( Lowercase letter z , minuscule z )
+ASCII code 123 = { ( braces or curly brackets, opening braces )
+ASCII code 124 = | ( vertical-bar, vbar, vertical line or vertical slash )
+ASCII code 125 = } ( curly brackets or braces, closing curly brackets )
+ASCII code 126 = ~ ( Tilde ; swung dash )
+ASCII Extended Characters :
+
+ASCII code 128 = Ç ( Majuscule C-cedilla )
+ASCII code 129 = ü ( letter u with umlaut or diaeresis , u-umlaut )
+ASCII code 130 = é ( letter e with acute accent or e-acute )
+ASCII code 131 = â ( letter a with circumflex accent or a-circumflex )
+ASCII code 132 = ä ( letter a with umlaut or diaeresis , a-umlaut )
+ASCII code 133 = à ( letter a with grave accent )
+ASCII code 134 = å ( letter a with a ring )
+ASCII code 135 = ç ( Minuscule c-cedilla )
+ASCII code 136 = ê ( letter e with circumflex accent or e-circumflex )
+ASCII code 137 = ë ( letter e with umlaut or diaeresis ; e-umlauts )
+ASCII code 138 = è ( letter e with grave accent )
+ASCII code 139 = ï ( letter i with umlaut or diaeresis ; i-umlaut )
+ASCII code 140 = î ( letter i with circumflex accent or i-circumflex )
+ASCII code 141 = ì ( letter i with grave accent )
+ASCII code 142 = Ä ( letter A with umlaut or diaeresis ; A-umlaut )
+ASCII code 143 = Å ( Capital letter A with a ring )
+ASCII code 144 = É ( Capital letter E with acute accent or E-acute )
+ASCII code 145 = æ ( Latin diphthong ae in lowercase )
+ASCII code 146 = Æ ( Latin diphthong AE in uppercase )
+ASCII code 147 = ô ( letter o with circumflex accent or o-circumflex )
+ASCII code 148 = ö ( letter o with umlaut or diaeresis ; o-umlaut )
+ASCII code 149 = ò ( letter o with grave accent )
+ASCII code 150 = û ( letter u with circumflex accent or u-circumflex )
+ASCII code 151 = ù ( letter u with grave accent )
+ASCII code 152 = ÿ ( Lowercase letter y with diaeresis )
+ASCII code 153 = Ö ( Letter O with umlaut or diaeresis ; O-umlaut )
+ASCII code 154 = Ü ( Letter U with umlaut or diaeresis ; U-umlaut )
+ASCII code 155 = ø ( Lowercase slashed zero or empty set )
+ASCII code 156 = £ ( Pound sign ; symbol for the pound sterling )
+ASCII code 157 = Ø ( Uppercase slashed zero or empty set )
+ASCII code 158 = × ( Multiplication sign )
+ASCII code 159 = ƒ ( Function sign ; f with hook sign ; florin sign )
+ASCII code 160 = á ( Lowercase letter a with acute accent or a-acute )
+ASCII code 161 = í ( Lowercase letter i with acute accent or i-acute )
+ASCII code 162 = ó ( Lowercase letter o with acute accent or o-acute )
+ASCII code 163 = ú ( Lowercase letter u with acute accent or u-acute )
+ASCII code 164 = ñ ( eñe, enie, spanish letter enye, lowercase n with tilde )
+ASCII code 165 = Ñ ( Spanish letter enye, uppercase N with tilde, EÑE, enie )
+ASCII code 166 = ª ( feminine ordinal indicator )
+ASCII code 167 = º ( masculine ordinal indicator )
+ASCII code 168 = ¿ ( Inverted question marks )
+ASCII code 169 = ® ( Registered trademark symbol )
+ASCII code 170 = ¬ ( Logical negation symbol )
+ASCII code 171 = ½ ( One half )
+ASCII code 172 = ¼ ( Quarter, one fourth )
+ASCII code 173 = ¡ ( Inverted exclamation marks )
+ASCII code 174 = « ( Angle quotes, guillemets, right-pointing quotation mark )
+ASCII code 175 = » ( Guillemets, angle quotes, left-pointing quotation marks )
+ASCII code 176 = ░ ( Graphic character, low density dotted )
+ASCII code 177 = ▒ ( Graphic character, medium density dotted )
+ASCII code 178 = ▓ ( Graphic character, high density dotted )
+ASCII code 179 = │ ( Box drawing character single vertical line )
+ASCII code 180 = ┤ ( Box drawing character single vertical and left line )
+ASCII code 181 = Á ( Capital letter A with acute accent or A-acute )
+ASCII code 182 = Â ( Letter A with circumflex accent or A-circumflex )
+ASCII code 183 = À ( Letter A with grave accent )
+ASCII code 184 = © ( Copyright symbol )
+ASCII code 185 = ╣ ( Box drawing character double line vertical and left )
+ASCII code 186 = ║ ( Box drawing character double vertical line )
+ASCII code 187 = ╗ ( Box drawing character double line upper right corner )
+ASCII code 188 = ╝ ( Box drawing character double line lower right corner )
+ASCII code 189 = ¢ ( Cent symbol )
+ASCII code 190 = ¥ ( YEN and YUAN sign )
+ASCII code 191 = ┐ ( Box drawing character single line upper right corner )
+ASCII code 192 = └ ( Box drawing character single line lower left corner )
+ASCII code 193 = ┴ ( Box drawing character single line horizontal and up )
+ASCII code 194 = ┬ ( Box drawing character single line horizontal down )
+ASCII code 195 = ├ ( Box drawing character single line vertical and right )
+ASCII code 196 = ─ ( Box drawing character single horizontal line )
+ASCII code 197 = ┼ ( Box drawing character single line horizontal vertical )
+ASCII code 198 = ã ( Lowercase letter a with tilde or a-tilde )
+ASCII code 199 = Ã ( Capital letter A with tilde or A-tilde )
+ASCII code 200 = ╚ ( Box drawing character double line lower left corner )
+ASCII code 201 = ╔ ( Box drawing character double line upper left corner )
+ASCII code 202 = ╩ ( Box drawing character double line horizontal and up )
+ASCII code 203 = ╦ ( Box drawing character double line horizontal down )
+ASCII code 204 = ╠ ( Box drawing character double line vertical and right )
+ASCII code 205 = ═ ( Box drawing character double horizontal line )
+ASCII code 206 = ╬ ( Box drawing character double line horizontal vertical )
+ASCII code 207 = ¤ ( Generic currency sign )
+ASCII code 208 = ð ( Lowercase letter eth )
+ASCII code 209 = Ð ( Capital letter Eth )
+ASCII code 210 = Ê ( Letter E with circumflex accent or E-circumflex )
+ASCII code 211 = Ë ( Letter E with umlaut or diaeresis, E-umlaut )
+ASCII code 212 = È ( Capital letter E with grave accent )
+ASCII code 213 = ı ( Lowercase dot less i )
+ASCII code 214 = Í ( Capital letter I with acute accent or I-acute )
+ASCII code 215 = Î ( Letter I with circumflex accent or I-circumflex )
+ASCII code 216 = Ï ( Letter I with umlaut or diaeresis ; I-umlaut )
+ASCII code 217 = ┘ ( Box drawing character single line lower right corner )
+ASCII code 218 = ┌ ( Box drawing character single line upper left corner )
+ASCII code 219 = █ ( Block, graphic character )
+ASCII code 220 = ▄ ( Bottom half block )
+ASCII code 221 = ¦ ( Vertical broken bar )
+ASCII code 222 = Ì ( Capital letter I with grave accent )
+ASCII code 223 = ▀ ( Top half block )
+ASCII code 224 = Ó ( Capital letter O with acute accent or O-acute )
+ASCII code 225 = ß ( Letter Eszett ; scharfes S or sharp S )
+ASCII code 226 = Ô ( Letter O with circumflex accent or O-circumflex )
+ASCII code 227 = Ò ( Capital letter O with grave accent )
+ASCII code 228 = õ ( Lowercase letter o with tilde or o-tilde )
+ASCII code 229 = Õ ( Capital letter O with tilde or O-tilde )
+ASCII code 230 = µ ( Lowercase letter Mu ; micro sign or micron )
+ASCII code 231 = þ ( Lowercase letter Thorn )
+ASCII code 232 = Þ ( Capital letter Thorn )
+ASCII code 233 = Ú ( Capital letter U with acute accent or U-acute )
+ASCII code 234 = Û ( Letter U with circumflex accent or U-circumflex )
+ASCII code 235 = Ù ( Capital letter U with grave accent )
+ASCII code 236 = ý ( Lowercase letter y with acute accent )
+ASCII code 237 = Ý ( Capital letter Y with acute accent )
+ASCII code 238 = ¯ ( Macron symbol )
+ASCII code 239 = ´ ( Acute accent )
+ASCII code 240 = ≡ ( Congruence relation symbol )
+ASCII code 241 = ± ( Plus-minus sign )
+ASCII code 242 = ‗ ( underline or underscore )
+ASCII code 243 = ¾ ( three quarters, three-fourths )
+ASCII code 244 = ¶ ( Paragraph sign or pilcrow ; end paragraph mark )
+ASCII code 245 = § ( Section sign )
+ASCII code 246 = ÷ ( The division sign ; Obelus )
+ASCII code 247 = ¸ ( cedilla )
+ASCII code 248 = ° ( Degree symbol )
+ASCII code 249 = ¨ ( Diaresis )
+ASCII code 250 = · ( Interpunct or space dot )
+ASCII code 251 = ¹ ( Superscript one, exponent 1, first power )
+ASCII code 252 = ³ ( Superscript three, exponent 3, cube, third power )
+ASCII code 253 = ² ( Superscript two, exponent 2, square, second power )
+ASCII code 254 = ■ ( black square )
+ASCII code 255 = nbsp ( Non-breaking space or no-break space )
