/**
 * crypto.subtle is not available on non-localhost http pages, which is pretty annoying for
 * testing OAuth2 PKCE flow in docker since we can't use localhost for container to container
 * communication. So here we provide a polyfill for sha256 - note that it only works with ascii
 * strings.
 */
export declare function sha256(str: string): Promise<ArrayBuffer | Uint8Array<ArrayBuffer>>;
/**
 * This function is useful in the OAuth Authorization Code with PKCE flow
 * when you need to hash the code_verifier into a code_challenge
 * const code_verifier = nanoid(43)
 * const code_challenge = await sha256andbase64url(code_verifier)
 */
export declare function sha256andbase64url(str: string): Promise<string>;