import { StorageBackend, StorageResult, S3StorageConfig, StorageUploadOptions } from './base';
export declare class S3StorageBackend implements StorageBackend {
    private config;
    readonly type: "s3";
    readonly hasPublicUrl = true;
    constructor(config: S3StorageConfig);
    init(): Promise<void>;
    upload(buffer: Buffer, filename: string): Promise<StorageResult>;
    uploadStream(stream: NodeJS.ReadableStream, filename: string, options?: StorageUploadOptions): Promise<StorageResult>;
    download(key: string): Promise<Buffer>;
    downloadStream(key: string): NodeJS.ReadableStream;
    delete(key: string): Promise<void>;
    exists(key: string): Promise<boolean>;
    private buildRequestTarget;
    private generateAuthorizationHeader;
    private getSigningKey;
    private joinUrlPath;
    private encodePath;
}