com.google.crypto.tink.hybrid.internal

Class HpkeUtil

java.lang.Object

com.google.crypto.tink.hybrid.internal.HpkeUtil

public final class HpkeUtil
extends Object

Collection of helper functions for HPKE.

Field Summary

Fields

Modifier and Type	Field and Description
static byte[]	AES_128_GCM_AEAD_ID
static byte[]	AES_256_GCM_AEAD_ID
static byte[]	AUTH_MODE
static byte[]	BASE_MODE
static byte[]	CHACHA20_POLY1305_AEAD_ID
static byte[]	EMPTY_SALT
static byte[]	HKDF_SHA256_KDF_ID
static byte[]	HKDF_SHA384_KDF_ID
static byte[]	HKDF_SHA512_KDF_ID
static byte[]	P256_HKDF_SHA256_KEM_ID
static byte[]	P384_HKDF_SHA384_KEM_ID
static byte[]	P521_HKDF_SHA512_KEM_ID
static byte[]	X25519_HKDF_SHA256_KEM_ID

Method Summary

Modifier and Type	Method and Description
static int	encodingSizeInBytes(HpkeParameters.KemId kemId) Returns the encapsulated key length (in bytes) for the specified kemId.
static int	getEncodedPrivateKeyLength(HpkeParameters.KemId kemId) Lengths from 'Nsk' column in https://www.rfc-editor.org/rfc/rfc9180.html#table-2.
static int	getEncodedPublicKeyLength(HpkeParameters.KemId kemId) Lengths from 'Npk' column in https://www.rfc-editor.org/rfc/rfc9180.html#table-2.
static byte[]	intToByteArray(int capacity, int value) Transforms a passed value to an MSB first byte array with the size of the specified capacity.

Methods inherited from class java.lang.Object

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

Field Detail

BASE_MODE

public static final byte[] BASE_MODE

AUTH_MODE

public static final byte[] AUTH_MODE

X25519_HKDF_SHA256_KEM_ID

public static final byte[] X25519_HKDF_SHA256_KEM_ID

P256_HKDF_SHA256_KEM_ID

public static final byte[] P256_HKDF_SHA256_KEM_ID

P384_HKDF_SHA384_KEM_ID

public static final byte[] P384_HKDF_SHA384_KEM_ID

P521_HKDF_SHA512_KEM_ID

public static final byte[] P521_HKDF_SHA512_KEM_ID

HKDF_SHA256_KDF_ID

public static final byte[] HKDF_SHA256_KDF_ID

HKDF_SHA384_KDF_ID

public static final byte[] HKDF_SHA384_KDF_ID

HKDF_SHA512_KDF_ID

public static final byte[] HKDF_SHA512_KDF_ID

AES_128_GCM_AEAD_ID

public static final byte[] AES_128_GCM_AEAD_ID

AES_256_GCM_AEAD_ID

public static final byte[] AES_256_GCM_AEAD_ID

CHACHA20_POLY1305_AEAD_ID

public static final byte[] CHACHA20_POLY1305_AEAD_ID

EMPTY_SALT

public static final byte[] EMPTY_SALT

Method Detail

intToByteArray

public static byte[] intToByteArray(int capacity,
                                    int value)

Transforms a passed value to an MSB first byte array with the size of the specified capacity. (i.e., Bytes.intToByteArray(int, int) with MSB first instead of LSB first).

The HPKE standard defines this function as I2OSP(n, w) where w = capacity and n = value.

https://www.rfc-editor.org/rfc/rfc9180.html#name-notation

Parameters:

capacity - size of the resulting byte array

value - that should be represented as a byte array

getEncodedPublicKeyLength

public static int getEncodedPublicKeyLength(HpkeParameters.KemId kemId)
                                     throws GeneralSecurityException

Lengths from 'Npk' column in https://www.rfc-editor.org/rfc/rfc9180.html#table-2.

Throws:

GeneralSecurityException

encodingSizeInBytes

public static int encodingSizeInBytes(HpkeParameters.KemId kemId)

Returns the encapsulated key length (in bytes) for the specified kemId. This value corresponds to the 'Nenc' column in the following table.

https://www.rfc-editor.org/rfc/rfc9180.html#name-key-encapsulation-mechanism.

getEncodedPrivateKeyLength

public static int getEncodedPrivateKeyLength(HpkeParameters.KemId kemId)
                                      throws GeneralSecurityException

Lengths from 'Nsk' column in https://www.rfc-editor.org/rfc/rfc9180.html#table-2.

Throws:

GeneralSecurityException