// For the base64 encoding pieces. const alphabet = [ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' ]; const values = {}; for (let i = 0; i < 64; ++i) { values[alphabet[i]] = i; } export function encode(bytes: ArrayBuffer): string { const array = new Uint8Array(bytes); const base64 = []; let index = 0; let quantum; let value; /* tslint:disable:no-bitwise */ // Grab as many sets of 3 bytes as we can, that form 24 bits. while (index + 2 < array.byteLength) { quantum = (array[index] << 16) | (array[index + 1] << 8) | array[index + 2]; // 24 bits will become 4 base64 chars. value = (quantum >> 18) & 0x3f; base64.push(alphabet[value]); value = (quantum >> 12) & 0x3f; base64.push(alphabet[value]); value = (quantum >> 6) & 0x3f; base64.push(alphabet[value]); value = quantum & 0x3f; base64.push(alphabet[value]); index += 3; } // At this point, there are 0, 1 or 2 bytes left. if (index + 1 === array.byteLength) { // 8 bits; shift by 4 to pad on the right with 0s to make 12 bits total. quantum = array[index] << 4; value = (quantum >> 6) & 0x3f; base64.push(alphabet[value]); value = quantum & 0x3f; base64.push(alphabet[value]); base64.push('=='); } else if (index + 2 === array.byteLength) { // 16 bits; shift by 2 to pad on the right with 0s to make 18 bits total. quantum = (array[index] << 10) | (array[index + 1] << 2); value = (quantum >> 12) & 0x3f; base64.push(alphabet[value]); value = (quantum >> 6) & 0x3f; base64.push(alphabet[value]); value = quantum & 0x3f; base64.push(alphabet[value]); base64.push('='); } /* tslint:enable:no-bitwise */ return base64.join(''); } export function decode(string: string): Uint8Array { let size = string.length; if (size === 0) { return new Uint8Array(new ArrayBuffer(0)); } if (size % 4 !== 0) { throw new Error('Bad length: ' + size); } if (!string.match(/^[a-zA-Z0-9+/]+={0,2}$/)) { throw new Error('Invalid base64 encoded value'); } // Every 4 base64 chars = 24 bits = 3 bytes. But, we also need to figure out // padding, if any. let bytes = 3 * (size / 4); let numPad = 0; if (string.charAt(size - 1) === '=') { numPad++; bytes--; } if (string.charAt(size - 2) === '=') { numPad++; bytes--; } const buffer = new Uint8Array(new ArrayBuffer(bytes)); let index = 0; let bufferIndex = 0; let quantum; if (numPad > 0) { size -= 4; // handle the last one specially } /* tslint:disable:no-bitwise */ while (index < size) { quantum = 0; for (let i = 0; i < 4; ++i) { quantum = (quantum << 6) | values[string.charAt(index + i)]; } // quantum is now a 24-bit value. buffer[bufferIndex++] = (quantum >> 16) & 0xff; buffer[bufferIndex++] = (quantum >> 8) & 0xff; buffer[bufferIndex++] = quantum & 0xff; index += 4; } if (numPad > 0) { // if numPad == 1, there is one =, and we have 18 bits with 2 0s at end. // if numPad == 2, there is two ==, and we have 12 bits with 4 0s at end. // First, grab my quantum. quantum = 0; for (let i = 0; i < 4 - numPad; ++i) { quantum = (quantum << 6) | values[string.charAt(index + i)]; } if (numPad === 1) { // quantum is 18 bits, but really represents two bytes. quantum = quantum >> 2; buffer[bufferIndex++] = (quantum >> 8) & 0xff; buffer[bufferIndex++] = quantum & 0xff; } else { // quantum is 12 bits, but really represents only one byte. quantum = quantum >> 4; buffer[bufferIndex++] = quantum & 0xff; } } /* tslint:enable:no-bitwise */ return buffer; }