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June 10, 2022 19:53
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Classe de criptografia/descriptografia base 64 JS
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| export class Base64 { | |
| private PADCHAR: string = '='; | |
| private ALPHA: string = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; | |
| private getByte(s: string, i: number): number { | |
| const x = s.charCodeAt(i); | |
| return x; | |
| } | |
| private getByte64(s: string, i: number): number { | |
| const idx = this.ALPHA.indexOf(s.charAt(i)); | |
| return idx; | |
| } | |
| public decode (s: string): string { | |
| let pads = 0, | |
| i, b10, imax = s.length, | |
| x = []; | |
| s = String(s); | |
| if (imax === 0) { | |
| return s; | |
| } | |
| if (s.charAt(imax - 1) === this.PADCHAR) { | |
| pads = 1; | |
| if (s.charAt(imax - 2) === this.PADCHAR) { | |
| pads = 2; | |
| } | |
| imax -= 4; | |
| } | |
| for (i = 0; i < imax; i += 4) { | |
| b10 = (this.getByte64(s, i) << 18) | (this.getByte64(s, i + 1) << 12) | (this.getByte64(s, i + 2) << 6) | this.getByte64(s, i + 3); | |
| x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 255, b10 & 255)); | |
| } | |
| switch (pads) { | |
| case 1: | |
| b10 = (this.getByte64(s, i) << 18) | (this.getByte64(s, i + 1) << 12) | (this.getByte64(s, i + 2) << 6); | |
| x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 255)); | |
| break; | |
| case 2: | |
| b10 = (this.getByte64(s, i) << 18) | (this.getByte64(s, i + 1) << 12); | |
| x.push(String.fromCharCode(b10 >> 16)); | |
| break; | |
| } | |
| return x.join(''); | |
| } | |
| public encode(s: string): string { | |
| s = String(s); | |
| let i, b10, x = [], | |
| imax = s.length - s.length % 3; | |
| if (s.length === 0) { | |
| return s; | |
| } | |
| for (i = 0; i < imax; i += 3) { | |
| b10 = (this.getByte(s, i) << 16) | (this.getByte(s, i + 1) << 8) | this.getByte(s, i + 2); | |
| x.push(this.ALPHA.charAt(b10 >> 18)); | |
| x.push(this.ALPHA.charAt((b10 >> 12) & 63)); | |
| x.push(this.ALPHA.charAt((b10 >> 6) & 63)); | |
| x.push(this.ALPHA.charAt(b10 & 63)); | |
| } | |
| switch (s.length - imax) { | |
| case 1: | |
| b10 = this.getByte(s, i) << 16; | |
| x.push(this.ALPHA.charAt(b10 >> 18) + this.ALPHA.charAt((b10 >> 12) & 63) + this.PADCHAR + this.PADCHAR); | |
| break; | |
| case 2: | |
| b10 = (this.getByte(s, i) << 16) | (this.getByte(s, i + 1) << 8); | |
| x.push(this.ALPHA.charAt(b10 >> 18) + this.ALPHA.charAt((b10 >> 12) & 63) + this.ALPHA.charAt((b10 >> 6) & 63) + this.PADCHAR); | |
| break; | |
| } | |
| return x.join(''); | |
| } | |
| } |
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