import { CHash, Input } from './utils.js';
/**
* HKDF-Extract(IKM, salt) -> PRK
* Arguments position differs from spec (IKM is first one, since it is not optional)
* @param hash
* @param ikm
* @param salt
* @returns
*/
export declare function extract(hash: CHash, ikm: Input, salt?: Input): Uint8Array;
/**
* HKDF-expand from the spec.
* @param prk - a pseudorandom key of at least HashLen octets (usually, the output from the extract step)
* @param info - optional context and application specific information (can be a zero-length string)
* @param length - length of output keying material in octets
*/
export declare function expand(hash: CHash, prk: Input, info?: Input, length?: number): Uint8Array;
/**
* HKDF (RFC 5869): extract + expand in one step.
* @param hash - hash function that would be used (e.g. sha256)
* @param ikm - input keying material, the initial key
* @param salt - optional salt value (a non-secret random value)
* @param info - optional context and application specific information
* @param length - length of output keying material in octets
*/
export declare const hkdf: (hash: CHash, ikm: Input, salt: Input | undefined, info: Input | undefined, length: number) => Uint8Array;
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