- Tech
- JavaScript implemented Base64 encoding and decoding
Base64 </ Title></p>
<p><script language = javaScript></p>
<p>VAR Base64Encodechars = "Abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789 /";</p>
<p>VAR Base64Decodechars = new array (</p>
<p>-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,</p>
<p>-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,</p>
<p>-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,</p>
<p>52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,</p>
<p>-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,</p>
<p>15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,</p>
<p>-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,</p>
<p>41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);</p>
<p>Function Base64encode (STR) {</p>
<p>VAR OUT, I, LEN;</p>
<p>VAR C1, C2, C3;</p>
<p>Len = str.length;</p>
<p>i = 0;</p>
<p>OUT = "";</p>
<p>While (i <len) {</p>
<p>C1 = Str.Charcodeat (i ) & 0xff;</p>
<p>IF (i == LEN)</p>
<p>{</p>
<p>Out = base64encodechars.Charat (C1 >> 2);</p>
<p>OUT = Base64encodechars.Charat ((C1 & 0x3) << 4);</p>
<p>OUT = "==";</p>
<p>Break;</p>
<p>}</p>
<p>C2 = str.charcodeat (i );</p>
<p>IF (i == LEN)</p>
<p>{</p>
<p>Out = base64encodechars.Charat (C1 >> 2);</p>
<p>OUT = Base64Encodechars.Charat (((C1 & 0x3) << 4) | ((C2 & 0xF0) >> 4));</p>
<p>OUT = Base64encodechars.Charat ((C2 & 0xF) << 2);</p>
<p>OUT = "=";</p>
<p>Break;</p>
<p>}</p>
<p>C3 = Str.Charcodeat (i );</p>
<p>Out = base64encodechars.Charat (C1 >> 2);</p>
<p>OUT = Base64Encodechars.Charat (((C1 & 0x3) << 4) | ((C2 & 0xF0) >> 4));</p>
<p>OUT = Base64Encodechars.Charat (((C2 & 0xF) << 2) | ((C3 & 0xC0) >> 6); out = base64encodechars.charat (C3 & 0x3f);</p>
<p>}</p>
<p>Return Out;</p>
<p>}</p>
<p>Function Base64Decode (str) {</p>
<p>VAR C1, C2, C3, C4;</p>
<p>VAR I, LEN, OUT;</p>
<p>Len = str.length;</p>
<p>i = 0;</p>
<p>OUT = "";</p>
<p>While (i <len) {</p>
<p>/ * c1 * /</p>
<p>Do {</p>
<p>C1 = base64decodechars [str.charcodeat (i ) & 0xff];</p>
<p>WHILE (I <LEN && C1 == -1);</p>
<p>IF (C1 == -1)</p>
<p>Break;</p>
<p>/ * C2 * /</p>
<p>Do {</p>
<p>C2 = Base64DecodeChars [str.charcodeat (i ) & 0xff];</p>
<p>WHILE (I <LEN && C2 == -1);</p>
<p>IF (C2 == -1)</p>
<p>Break;</p>
<p>OUT = String.Fromcharcode ((C1 << 2) | ((C2 & 0x30) >> 4));</p>
<p>/ * C3 * /</p>
<p>Do {</p>
<p>C3 = Str.Charcodeat (i ) & 0xff;</p>
<p>IF (C3 == 61)</p>
<p>Return Out;</p>
<p>C3 = base64decodechars [c3];</p>
<p>WHILE (I <LEN && C3 == -1);</p>
<p>IF (C3 == -1)</p>
<p>Break;</p>
<p>OUT = String.Fromcharcode (((C2 & 0xF) << 4) | ((C3 & 0x3c) >> 2));</p>
<p>/ * C4 * /</p>
<p>Do {</p>
<p>C4 = Str.Charcodeat (i ) & 0xff;</p>
<p>IF (C4 == 61)</p>
<p>Return Out;</p>
<p>C4 = base64decodechars [c4];</p>
<p>WHILE (I <LEN && C4 == -1);</p>
<p>IF (C4 == -1)</p>
<p>Break;</p>
<p>OUT = String.fromcharcode (((C3 & 0x03) << 6) | C4);</p>
<p>}</p>
<p>Return Out;</p>
<p>}</p>
<p>Function UTF16TO8 (STR) {</p>
<p>VAR OUT, I, LEN, C;</p>
<p>OUT = "";</p>
<p>Len = str.length;</p>
<p>For (i = 0; i <len; i ) {</p>
<p>C = str.charcodeat (i);</p>
<p>IF ((c> = 0x0001) && (c <= 0x007f)) {</p>
<p>OUT = Str.Charat (i);</p>
<p>} else IF (c> 0x07ff) {</p>
<p>OUT = String.Fromcharcode (0xE0 | ((C >> 12) & 0x0f);</p>
<p>Out = string.fromcharcode (0x80 | ((c >> 6) & 0x3f); out = string.fromcharcode (0x80 | (((c >> 0) & 0x3f));</p>
<p>} else {</p>
<p>Out = string.fromcharcode (0xc0 | ((c >> 6) & 0x1f);</p>
<p>Out = string.fromcharcode (0x80 | (((c >> 0) & 0x3f);</p>
<p>}</p>
<p>}</p>
<p>Return Out;</p>
<p>}</p>
<p>Function UTF8TO16 (STR) {</p>
<p>VAR OUT, I, LEN, C;</p>
<p>Var Char2, Char3;</p>
<p>OUT = "";</p>
<p>Len = str.length;</p>
<p>i = 0;</p>
<p>While (i <len) {</p>
<p>C = str.charcodeat (i );</p>
<p>Switch (c >> 4)</p>
<p>{</p>
<p>Case 0: Case 1: Case 2: Case 3: Case 4: Case 5: Case 6: Case 7:</p>
<p>// 0xxxxxxx</p>
<p>OUT = str.charat (i-1);</p>
<p>Break;</p>
<p>Case 12: Case 13:</p>
<p>// 110x xxxx 10xx xxxx</p>
<p>Char2 = str.charcodeat (i );</p>
<p>Out = string.fromcharcode ((C & 0x1f) << 6) | (char2 & 0x3f));</p>
<p>Break;</p>
<p>Case 14:</p>
<p>// 1110 xxxx 10xx xxxx 10xx xxxx</p>
<p>Char2 = str.charcodeat (i );</p>
<p>Char3 = str.charcodeat (i );</p>
<p>Out = string.fromcharcode (((c & 0x0f) << 12) |</p>
<p>((char2 & 0x3f) << 6) |</p>
<p>((Char3 & 0x3f) << 0));</p>
<p>Break;</p>
<p>}</p>
<p>}</p>
<p>Return Out;</p>
<p>}</p>
<p>Function DOIT () {</p>
<p>VAR f = Document.f</p>
<p>f.output.value = base64encode (UTF16TO8 (F.Source.Value))</p>
<p>f.Decode.Value = UTF8TO16 (Base64Decode (f.output.value))</p>
<p>}</p>
<p></ script></p>
<p></ HEAD></p>
<p><Body></p>
<p><H1> Base64 </ h1></p>
<p><Form name = "f"></p>
<p>Original code <br></p>
<p><TEXTAREA NAME = "source" ROWS = 4 COLS = 60 WRAP = "soft"> </ TEXTAREA> <BR> <BR></p>
<p>Base64 encode <br></p>
<p><TEXTAREA NAME = "output" ROWS = 4 COLS = 60 WRAP = "soft"> </ TEXTAREA> <BR> <BR></p>
<p>Base64 Decode <br></p>
<p><TEXTAREA NAME = "decode" ROWS = 4 COLS = 60 WRAP = "soft"> </ TEXTAREA> <BR> <BR> <INPUT TYPE = BUTTON VALUE = "conversion" ONCLICK = "doit ()"></p>
<p></ Form></p>
<p></ Body></p></div><div class="text-center mt-3 text-grey">
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