iaik.security.ec.common

Class HKDFParameterSpec

java.lang.Object

iaik.security.ec.common.HKDFParameterSpec

All Implemented Interfaces:

KDFParameterSpec, AlgorithmParameterSpec

public final class HKDFParameterSpec
extends Object
implements KDFParameterSpec

Parameter class for the HKDF key derivation function as specified in [1], [2] and [32].

References:

[1] RFC 5869, HMAC-based Extract-and-Expand Key Derivation Function (HKDF), see RFC 5869

[2] RFC 8418, Use of the Elliptic Curve Diffie-Hellman Key Agreement Algorithm with X25519 and X448 in the Cryptographic Message Syntax (CMS), see RFC 8418

[3] RFC 8619, Algorithm Identifiers for the HMAC-based Extract-and-Expand Key Derivation Function (HKDF), see RFC 8619

The parameters consist of hash algorithm to be used, the length of the key to be generated, optional shared information and user keying material. The shared information represents the optional context and application specific information input to the expand function, and the user keying material represents the optional salt input to the extract function.

The toASN1Object() method of this HKDFParameterSpec class returns the HKDF algorithm identifier according to RFC 8619 depending on the hash function that is used:

 id-alg-hkdf-with-sha256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 28 }

 id-alg-hkdf-with-sha384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 29 }

 id-alg-hkdf-with-sha512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 30 }
 

See Also:

HKDF, ECDHParameterSpec, ECDHKeyAgreement, ECDHWithCofactorKeyAgreement

Constructor Summary

Constructors

Constructor and Description
HKDFParameterSpec(iaik.asn1.structures.AlgorithmID hashAlgID, int keyLength, byte[] sharedInformation, byte[] ukm) Creates a new HKDF parameter spec object with shared information.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
iaik.asn1.structures.AlgorithmID	getID() Retruns returns the HKDF algorithm identifier for this HKDFParameterSpec according to RFC 8619.
int	getKeyLength() Returns the length of the key to be generated.
byte[]	getSharedInformation() Returns the optional shared information.
byte[]	getUKM() Returns the optional user keying material.
int	hashCode()
iaik.asn1.ASN1Object	toASN1Object() This method returns the HKDF algorithm identifier for this HKDFParameterSpec as ASN1Object according to RFC 8619.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HKDFParameterSpec

public HKDFParameterSpec(iaik.asn1.structures.AlgorithmID hashAlgID,
                         int keyLength,
                         byte[] sharedInformation,
                         byte[] ukm)

Creates a new HKDF parameter spec object with shared information.

Parameters:

hashAlgID - the message digest algorithm id that will be used to derive the keying data

keyLength - the length of the key to be generated/derived in bits

sharedInformation - an octet string holding the shared information

ukm - optional user keying material of the sender (used as HKF salt)

Method Detail

getKeyLength

public int getKeyLength()

Returns the length of the key to be generated.

Returns:

the length of the key in bits

getSharedInformation

public byte[] getSharedInformation()

Returns the optional shared information.

Returns:

either an octet-string holding the shared information or null if no shared information is available

getUKM

public byte[] getUKM()

Returns the optional user keying material.

Returns:

either an octet-string holding the user keying material or null if no user keying material is available.

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getID

public iaik.asn1.structures.AlgorithmID getID()

Retruns returns the HKDF algorithm identifier for this HKDFParameterSpec according to RFC 8619.

RFC 8619 specifies the following algorithm identifiers for HKDF:

 id-alg-hkdf-with-sha256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 28 }

 id-alg-hkdf-with-sha384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 29 }

 id-alg-hkdf-with-sha512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 30 }
 

Returns:

the HKDF algorithm identifier

toASN1Object

public iaik.asn1.ASN1Object toASN1Object()

This method returns the HKDF algorithm identifier for this HKDFParameterSpec as ASN1Object according to RFC 8619.

RFC 8619 specifies the following algorithm identifiers for HKDF:

 id-alg-hkdf-with-sha256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 28 }

 id-alg-hkdf-with-sha384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 29 }

 id-alg-hkdf-with-sha512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
    us(840) rsadsi(113549) pkcs(1) pkcs-9(9) smime(16) alg(3) 30 }
 

Specified by:

toASN1Object in interface KDFParameterSpec

Returns:

the HKDF algorithm identifier as ASN1Object