51 lines
1.6 KiB
JavaScript
51 lines
1.6 KiB
JavaScript
/* @flow */
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import { randomBytes, createHash } from 'crypto';
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// Returns a new random hex string of the given even size.
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export function randomHexString(size: number): string {
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if (size === 0) {
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throw new Error('Zero-length randomHexString is useless.');
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}
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if (size % 2 !== 0) {
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throw new Error('randomHexString size must be divisible by 2.')
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}
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return randomBytes(size / 2).toString('hex');
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}
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// Returns a new random alphanumeric string of the given size.
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//
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// Note: to simplify implementation, the result has slight modulo bias,
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// because chars length of 62 doesn't divide the number of all bytes
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// (256) evenly. Such bias is acceptable for most cases when the output
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// length is long enough and doesn't need to be uniform.
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export function randomString(size: number): string {
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if (size === 0) {
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throw new Error('Zero-length randomString is useless.');
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}
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const chars = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
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'abcdefghijklmnopqrstuvwxyz' +
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'0123456789');
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let objectId = '';
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const bytes = randomBytes(size);
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for (let i = 0; i < bytes.length; ++i) {
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objectId += chars[bytes.readUInt8(i) % chars.length];
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}
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return objectId;
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}
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// Returns a new random alphanumeric string suitable for object ID.
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export function newObjectId(): string {
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//TODO: increase length to better protect against collisions.
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return randomString(10);
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}
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// Returns a new random hex string suitable for secure tokens.
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export function newToken(): string {
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return randomHexString(32);
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}
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export function md5Hash(string: string): string {
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return createHash('md5').update(string).digest('hex');
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}
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