diff options
Diffstat (limited to 'std/encoding/base32.ts')
| -rw-r--r-- | std/encoding/base32.ts | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/std/encoding/base32.ts b/std/encoding/base32.ts new file mode 100644 index 000000000..444c2136d --- /dev/null +++ b/std/encoding/base32.ts @@ -0,0 +1,218 @@ +// Modified from https://github.com/beatgammit/base64-js +// Copyright (c) 2014 Jameson Little. MIT License. + +const lookup: string[] = []; +const revLookup: number[] = []; + +// RFC4648 base32 +const code = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"; +for (let i = 0, len = code.length; i < len; ++i) { + lookup[i] = code[i]; + revLookup[code.charCodeAt(i)] = i; +} + +const placeHolderPadLookup = [0, 1, , 2, 3, , 4]; +function _getPadLen(placeHoldersLen: number): number { + const maybeLen = placeHolderPadLookup[placeHoldersLen]; + if (maybeLen === undefined) { + throw new Error("Invalid pad length"); + } + return maybeLen!; +} + +function getLens(b32: string): [number, number] { + const len = b32.length; + + if (len % 8 > 0) { + throw new Error("Invalid string. Length must be a multiple of 8"); + } + + let validLen = b32.indexOf("="); + if (validLen === -1) validLen = len; + + const placeHoldersLen = validLen === len ? 0 : 8 - (validLen % 8); + + return [validLen, placeHoldersLen]; +} + +/** + * Returns number of bytes encoded in the given RFC4648 base32 string input. + * @param b32 + */ +export function byteLength(b32: string): number { + const [validLen, placeHoldersLen] = getLens(b32); + return _byteLength(validLen, placeHoldersLen); +} + +function _byteLength(validLen: number, placeHoldersLen: number): number { + return ((validLen + placeHoldersLen) * 5) / 8 - _getPadLen(placeHoldersLen); +} + +/** + * Decodes a given RFC4648 base32 encoded string. + * @param b32 + */ +export function decode(b32: string): Uint8Array { + let tmp: number; + const [validLen, placeHoldersLen] = getLens(b32); + + const arr = new Uint8Array(_byteLength(validLen, placeHoldersLen)); + + let curByte = 0; + + // if there are placeholders, only get up to the last complete 8 chars + const len = placeHoldersLen > 0 ? validLen - 8 : validLen; + + let i: number; + for (i = 0; i < len; i += 8) { + tmp = + (revLookup[b32.charCodeAt(i)] << 20) | + (revLookup[b32.charCodeAt(i + 1)] << 15) | + (revLookup[b32.charCodeAt(i + 2)] << 10) | + (revLookup[b32.charCodeAt(i + 3)] << 5) | + revLookup[b32.charCodeAt(i + 4)]; + arr[curByte++] = (tmp >> 17) & 0xff; + arr[curByte++] = (tmp >> 9) & 0xff; + arr[curByte++] = (tmp >> 1) & 0xff; + + tmp = + ((tmp & 1) << 15) | + (revLookup[b32.charCodeAt(i + 5)] << 10) | + (revLookup[b32.charCodeAt(i + 6)] << 5) | + revLookup[b32.charCodeAt(i + 7)]; + arr[curByte++] = (tmp >> 8) & 0xff; + arr[curByte++] = tmp & 0xff; + } + + if (placeHoldersLen === 1) { + tmp = + (revLookup[b32.charCodeAt(i)] << 20) | + (revLookup[b32.charCodeAt(i + 1)] << 15) | + (revLookup[b32.charCodeAt(i + 2)] << 10) | + (revLookup[b32.charCodeAt(i + 3)] << 5) | + revLookup[b32.charCodeAt(i + 4)]; + arr[curByte++] = (tmp >> 17) & 0xff; + arr[curByte++] = (tmp >> 9) & 0xff; + arr[curByte++] = (tmp >> 1) & 0xff; + tmp = + ((tmp & 1) << 7) | + (revLookup[b32.charCodeAt(i + 5)] << 2) | + (revLookup[b32.charCodeAt(i + 6)] >> 3); + arr[curByte++] = tmp & 0xff; + } else if (placeHoldersLen === 3) { + tmp = + (revLookup[b32.charCodeAt(i)] << 19) | + (revLookup[b32.charCodeAt(i + 1)] << 14) | + (revLookup[b32.charCodeAt(i + 2)] << 9) | + (revLookup[b32.charCodeAt(i + 3)] << 4) | + (revLookup[b32.charCodeAt(i + 4)] >> 1); + arr[curByte++] = (tmp >> 16) & 0xff; + arr[curByte++] = (tmp >> 8) & 0xff; + arr[curByte++] = tmp & 0xff; + } else if (placeHoldersLen === 4) { + tmp = + (revLookup[b32.charCodeAt(i)] << 11) | + (revLookup[b32.charCodeAt(i + 1)] << 6) | + (revLookup[b32.charCodeAt(i + 2)] << 1) | + (revLookup[b32.charCodeAt(i + 3)] >> 4); + arr[curByte++] = (tmp >> 8) & 0xff; + arr[curByte++] = tmp & 0xff; + } else if (placeHoldersLen === 6) { + tmp = + (revLookup[b32.charCodeAt(i)] << 3) | + (revLookup[b32.charCodeAt(i + 1)] >> 2); + arr[curByte++] = tmp & 0xff; + } + + return arr; +} + +function encodeChunk(uint8: Uint8Array, start: number, end: number): string { + let tmp: number; + const output = []; + for (let i = start; i < end; i += 5) { + tmp = + ((uint8[i] << 16) & 0xff0000) | + ((uint8[i + 1] << 8) & 0xff00) | + (uint8[i + 2] & 0xff); + output.push(lookup[(tmp >> 19) & 0x1f]); + output.push(lookup[(tmp >> 14) & 0x1f]); + output.push(lookup[(tmp >> 9) & 0x1f]); + output.push(lookup[(tmp >> 4) & 0x1f]); + tmp = + ((tmp & 0xf) << 16) | + ((uint8[i + 3] << 8) & 0xff00) | + (uint8[i + 4] & 0xff); + output.push(lookup[(tmp >> 15) & 0x1f]); + output.push(lookup[(tmp >> 10) & 0x1f]); + output.push(lookup[(tmp >> 5) & 0x1f]); + output.push(lookup[tmp & 0x1f]); + } + return output.join(""); +} + +/** + * Encodes a given Uint8Array into RFC4648 base32 representation + * @param uint8 + */ +export function encode(uint8: Uint8Array): string { + let tmp: number; + const len = uint8.length; + const extraBytes = len % 5; + const parts = []; + const maxChunkLength = 16385; // must be multiple of 5 + const len2 = len - extraBytes; + + // go through the array every 5 bytes, we'll deal with trailing stuff later + for (let i = 0; i < len2; i += maxChunkLength) { + parts.push( + encodeChunk( + uint8, + i, + i + maxChunkLength > len2 ? len2 : i + maxChunkLength + ) + ); + } + + // pad the end with zeros, but make sure to not forget the extra bytes + if (extraBytes === 4) { + tmp = + ((uint8[len2] & 0xff) << 16) | + ((uint8[len2 + 1] & 0xff) << 8) | + (uint8[len2 + 2] & 0xff); + parts.push(lookup[(tmp >> 19) & 0x1f]); + parts.push(lookup[(tmp >> 14) & 0x1f]); + parts.push(lookup[(tmp >> 9) & 0x1f]); + parts.push(lookup[(tmp >> 4) & 0x1f]); + tmp = ((tmp & 0xf) << 11) | (uint8[len2 + 3] << 3); + parts.push(lookup[(tmp >> 10) & 0x1f]); + parts.push(lookup[(tmp >> 5) & 0x1f]); + parts.push(lookup[tmp & 0x1f]); + parts.push("="); + } else if (extraBytes === 3) { + tmp = + ((uint8[len2] & 0xff) << 17) | + ((uint8[len2 + 1] & 0xff) << 9) | + ((uint8[len2 + 2] & 0xff) << 1); + parts.push(lookup[(tmp >> 20) & 0x1f]); + parts.push(lookup[(tmp >> 15) & 0x1f]); + parts.push(lookup[(tmp >> 10) & 0x1f]); + parts.push(lookup[(tmp >> 5) & 0x1f]); + parts.push(lookup[tmp & 0x1f]); + parts.push("==="); + } else if (extraBytes === 2) { + tmp = ((uint8[len2] & 0xff) << 12) | ((uint8[len2 + 1] & 0xff) << 4); + parts.push(lookup[(tmp >> 15) & 0x1f]); + parts.push(lookup[(tmp >> 10) & 0x1f]); + parts.push(lookup[(tmp >> 5) & 0x1f]); + parts.push(lookup[tmp & 0x1f]); + parts.push("===="); + } else if (extraBytes === 1) { + tmp = (uint8[len2] & 0xff) << 2; + parts.push(lookup[(tmp >> 5) & 0x1f]); + parts.push(lookup[tmp & 0x1f]); + parts.push("======"); + } + + return parts.join(""); +} |