{"id":645,"date":"2020-05-11T10:14:20","date_gmt":"2020-05-11T10:14:20","guid":{"rendered":"https:\/\/blog.samarthya.me\/wps\/?p=645"},"modified":"2020-05-11T10:16:16","modified_gmt":"2020-05-11T10:16:16","slug":"golang-simplecipher","status":"publish","type":"post","link":"https:\/\/blog.samarthya.me\/wps\/2020\/05\/11\/golang-simplecipher\/","title":{"rendered":"GoLang: SimpleCipher"},"content":{"rendered":"

Hello back again, Golang is just a new syntax for me. Even though behind the scenes they developers have simplified many things, for a consumer like me writing a program is more about learning the new syntax and getting familiarized with the control and stack.<\/p>\n

In my constant quest to try something different, today I try and solve the simple cipher which by definition is a text replacement algorithm that makes the text a little difficult to break while reading with naked eyes.<\/p>\n

SimpleCipher<\/a>: Code available in GitHub<\/p>\n

<\/p>\n

Version 1.0<\/h2>\n
The first version was a basic logic writing which allowed to check for the code and decode capability.<\/pre>\n\n\n
\/\/ Encrypt struct\ntype Encrypt struct {\n\tdistance int\n\tkey      string\n}\n\n\/\/ NewCaesar Object that implements the interface Cipher\nfunc NewCaesar() Cipher {\n\treturn Encrypt{distance: 3, key: \"\"}\n}\n\n\/\/ NewShift Object that implements the interface Cipher\nfunc NewShift(distance int) Cipher {\n\t\/\/ Corner case when of 0, 26, -26\n\tif distance < -26 || distance > 26 || distance == 0 {\n\t\treturn nil\n\t}\n\treturn Encrypt{distance, \"\"}\n}\n\n\/\/ NewVigenere Object that implements the interface Cipher\nfunc NewVigenere(key string) Cipher {\n\n\tif key == \"\" || checkKeyInvalid(key) {\n\t\treturn nil\n\t}\n\treturn Encrypt{0, key}\n}\n\n\/\/ checkAllAs Checks for all A's in the key.\nfunc checkKeyInvalid(s string) (f bool) {\n\n\t\/\/ If any invalid character matches\n\tif matched, _ := regexp.MatchString(`[^a-z]`, s); matched {\n\t\treturn true\n\t}\n\n\tfor _, m := range s {\n\t\tswitch m {\n\t\tcase 'a':\n\t\t\tf = true\n\t\tdefault:\n\t\t\tf = false\n\t\t\treturn\n\t\t}\n\t}\n\treturn\n}<\/code><\/pre>\n\n\n\n
I also wrote a utility to remove all invalid character basically all the chars that were not either of A-Z or a-z.<\/p>\n\n\n\n
\/\/ removeAllOtherCharcterBeforeEncoding replace all the other elements\nfunc removeAllOtherCharcterBeforeEncoding(s string) (o string) {\n\to = RegularExp.ReplaceAllString(s, \"\")\n\tlog.Printf(\" String: %s\", o)\n\to = strings.ToLower(o)\n\treturn\n}\n\nvar RegularExp = regexp.MustCompile(`[^A-Za-z]`)<\/code><\/pre>\n\n\n\n
The basic logic of transforming the input string to encoded string was written in these two functions below<\/p>\n\n\n\n
func transformWithString(s string, e string, flag bool) string {\n\tvar sb strings.Builder\n\n\tem := []rune(e)\n\n\tfor i, sm := range s {\n\t\t\/\/ The key has to be repeated\n\t\tvar d rune = 0\n\n\t\tif i < len(em) {\n\t\t\td = em[i] - 'a'\n\t\t} else {\n\t\t\td = em[(i%len(em))] - 'a'\n\t\t}\n\n\t\tif flag {\n\t\t\tswitch {\n\t\t\tcase sm >= 'a' && sm <= 'z':\n\t\t\t\tfmt.Fprintf(&sb, \"%s\", string('a'+(sm-'a'+d)%26))\n\t\t\t}\n\t\t} else {\n\t\t\tswitch {\n\t\t\tcase sm >= 'a' && sm <= 'z':\n\t\t\t\tdiff := ((sm - 'a' - d) % 26)\n\t\t\t\tnewChar := \"\"\n\n\t\t\t\tif diff < 0 {\n\t\t\t\t\tnewChar = string('z' + diff + 1)\n\t\t\t\t} else {\n\t\t\t\t\tnewChar = string('a' + diff)\n\t\t\t\t}\n\t\t\t\tfmt.Fprintf(&sb, \"%s\", newChar)\n\t\t\t}\n\t\t}\n\t}\n\treturn sb.String()\n}\n\n\/\/ transformWithDistance Allows transformation based on distance.\nfunc transformWithDistance(s string, d int) string {\n\n\trotateFunction := func(r rune) rune {\n\t\tswitch {\n\t\tcase r >= 'a' && r <= 'z':\n\t\t\tval := (r - 'a' + rune(d))\n\t\t\tif val < 0 && d < 0 {\n\t\t\t\treturn 'z' + ((val + 1) % 26)\n\t\t\t}\n\t\t\treturn 'a' + (val % 26)\n\n\t\tdefault:\n\t\t\tlog.Printf(\" Not a charcter: %s\", string(r))\n\t\t}\n\t\treturn ' '\n\t}\n\n\treturn strings.Map(rotateFunction, s)\n\n}<\/code><\/pre>\n\n\n\n
The basic functions that invoke these encode and decode functions are as under<\/p>\n\n\n\n
\/\/ Encode Implements the interface Cipher\nfunc (e Encrypt) Encode(s string) (o string) {\n\to = \"\"\n\ts = removeAllOtherCharcterBeforeEncoding(s)\n\n\tif s == \"\" || len(s) <= 0 {\n\t\treturn\n\t}\n\n\t\/\/ Iterate throught the runes\n\n\tswitch {\n\tcase e.distance != 0:\n\t\to = strings.ReplaceAll(transformWithDistance(s, e.distance), \" \", \"\")\n\tdefault:\n\t\to = transformWithString(s, e.key, true)\n\t}\n\n\treturn\n}\n\n\/\/ Decode decides the encrypted string\nfunc (e Encrypt) Decode(s string) (o string) {\n\to = \"\"\n\n\tlog.Printf(\" Decode: %s\", s)\n\n\tif s == \"\" || len(s) <= 0 {\n\t\treturn\n\t}\n\n\tswitch {\n\tcase e.distance != 0:\n\t\tlog.Printf(\" Distance: %d\", e.distance)\n\t\to = transformWithDistance(s, -e.distance)\n\tdefault:\n\t\to = transformWithString(s, e.key, false)\n\t}\n\n\treturn\n}<\/code><\/pre>\n\n\n\n
Now the general feeling after writing this was I have too much the same code that I should remove for example<\/p>\n\n\n\n
  • transformWithDistance<\/li>
  • transformWithString<\/li><\/ul>\n\n\n\n
    They are essentially doing the same thing?<\/p>\n\n\n\n
    <\/p>\n\n\n\n
    Version 2…. to follow soon.<\/p>\n","protected":false},"excerpt":{"rendered":"
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