Class AesGcmHkdfAeadCrypter

java.lang.Object

io.grpc.alts.internal.AesGcmHkdfAeadCrypter

All Implemented Interfaces:

AeadCrypter

final class AesGcmHkdfAeadCrypter
extends Object
implements AeadCrypter

AeadCrypter implementation based on AesGcmAeadCrypter with nonce-based rekeying using HKDF-expand and random nonce-mask that is XORed with the given nonce/counter. The AES-GCM key is computed as HKDF-expand(kdfKey, nonce[2..7]), i.e., the first 2 bytes are ignored to require rekeying only after 2^16 operations and the last 4 bytes (including the direction bit) are ignored to allow for optimizations (use same AEAD context for both directions, store counter as unsigned long and boolean for direction).

Field Summary

Fields

Modifier and Type	Field	Description
private AeadCrypter	aeadCrypter
private static final int	KDF_COUNTER_LENGTH
private static final int	KDF_COUNTER_OFFSET
private static final int	KDF_KEY_LENGTH
private final byte[]	kdfCounter
private final byte[]	kdfKey
private static final int	KEY_LENGTH
private static final int	NONCE_LENGTH
private final byte[]	nonceBuffer
private final byte[]	nonceMask

Constructor Summary

Constructors

Constructor	Description
AesGcmHkdfAeadCrypter(byte[] key)

Method Summary

Modifier and Type	Method	Description
private static boolean	arrayEqualOn(byte[] a, int aPos, byte[] b, int bPos, int length)
void	decrypt(ByteBuffer plaintext, ByteBuffer ciphertext, byte[] nonce)	Decrypt ciphertext into plaintext buffer using the given nonce.
void	decrypt(ByteBuffer plaintext, ByteBuffer ciphertext, ByteBuffer aad, byte[] nonce)	Decrypt ciphertext into plaintext buffer using the given nonce.
void	encrypt(ByteBuffer ciphertext, ByteBuffer plaintext, byte[] nonce)	Encrypt plaintext into ciphertext buffer using the given nonce.
void	encrypt(ByteBuffer ciphertext, ByteBuffer plaintext, ByteBuffer aad, byte[] nonce)	Encrypt plaintext into ciphertext buffer using the given nonce with authenticated data.
(package private) static int	getKeyLength()
private static byte[]	hkdfExpandSha256(byte[] key, byte[] info)
private static void	maskNonce(byte[] nonceBuffer, byte[] nonceMask, byte[] nonce)
private void	maybeRekey(byte[] nonce)

Methods inherited from class Object

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

Field Details

KDF_KEY_LENGTH

private static final int KDF_KEY_LENGTH

See Also:

• Constant Field Values

KDF_COUNTER_OFFSET

private static final int KDF_COUNTER_OFFSET

See Also:

• Constant Field Values

KDF_COUNTER_LENGTH

private static final int KDF_COUNTER_LENGTH

See Also:

• Constant Field Values

NONCE_LENGTH

private static final int NONCE_LENGTH

See Also:

• Constant Field Values

KEY_LENGTH

private static final int KEY_LENGTH

See Also:

• Constant Field Values

kdfKey

private final byte[] kdfKey

kdfCounter

private final byte[] kdfCounter

nonceMask

private final byte[] nonceMask

nonceBuffer

private final byte[] nonceBuffer

aeadCrypter

private AeadCrypter aeadCrypter

Constructor Details

AesGcmHkdfAeadCrypter

AesGcmHkdfAeadCrypter(byte[] key)

Method Details

encrypt

public void encrypt(ByteBuffer ciphertext,
 ByteBuffer plaintext,
 byte[] nonce)
             throws GeneralSecurityException

Description copied from interface: AeadCrypter

Encrypt plaintext into ciphertext buffer using the given nonce.

Specified by:

encrypt in interface AeadCrypter

Parameters:

ciphertext - the encrypted plaintext and the tag will be written into this buffer.

plaintext - the input that should be encrypted.

nonce - the unique nonce used for the encryption.

Throws:

GeneralSecurityException - if ciphertext buffer is short or the nonce does not have the expected size.

encrypt

public void encrypt(ByteBuffer ciphertext,
 ByteBuffer plaintext,
 ByteBuffer aad,
 byte[] nonce)
             throws GeneralSecurityException

Description copied from interface: AeadCrypter

Encrypt plaintext into ciphertext buffer using the given nonce with authenticated data.

Specified by:

encrypt in interface AeadCrypter

Parameters:

ciphertext - the encrypted plaintext and the tag will be written into this buffer.

plaintext - the input that should be encrypted.

aad - additional data that should be authenticated, but not encrypted.

nonce - the unique nonce used for the encryption.

Throws:

GeneralSecurityException - if ciphertext buffer is short or the nonce does not have the expected size.

decrypt

public void decrypt(ByteBuffer plaintext,
 ByteBuffer ciphertext,
 byte[] nonce)
             throws GeneralSecurityException

Description copied from interface: AeadCrypter

Decrypt ciphertext into plaintext buffer using the given nonce.

Specified by:

decrypt in interface AeadCrypter

Parameters:

plaintext - the decrypted plaintext will be written into this buffer.

ciphertext - the ciphertext and tag that should be decrypted.

nonce - the nonce that was used for the encryption.

Throws:

GeneralSecurityException - if the tag is invalid or any of the inputs do not have the expected size.

decrypt

public void decrypt(ByteBuffer plaintext,
 ByteBuffer ciphertext,
 ByteBuffer aad,
 byte[] nonce)
             throws GeneralSecurityException

Description copied from interface: AeadCrypter

Decrypt ciphertext into plaintext buffer using the given nonce.

Specified by:

decrypt in interface AeadCrypter

Parameters:

plaintext - the decrypted plaintext will be written into this buffer.

ciphertext - the ciphertext and tag that should be decrypted.

aad - additional data that is checked for authenticity.

nonce - the nonce that was used for the encryption.

Throws:

GeneralSecurityException - if the tag is invalid or any of the inputs do not have the expected size.

maybeRekey

private void maybeRekey(byte[] nonce)
                 throws GeneralSecurityException

Throws:

GeneralSecurityException

maskNonce

private static void maskNonce(byte[] nonceBuffer,
 byte[] nonceMask,
 byte[] nonce)

hkdfExpandSha256

private static byte[] hkdfExpandSha256(byte[] key,
 byte[] info)
                                throws GeneralSecurityException

Throws:

GeneralSecurityException

arrayEqualOn

private static boolean arrayEqualOn(byte[] a,
 int aPos,
 byte[] b,
 int bPos,
 int length)

getKeyLength

static int getKeyLength()