com.google.crypto.tink.internal

Class KeyTypeManager.KeyFactory<KeyFormatProtoT extends com.google.protobuf.MessageLite,KeyProtoT extends com.google.protobuf.MessageLite>

java.lang.Object

com.google.crypto.tink.internal.KeyTypeManager.KeyFactory<KeyFormatProtoT,KeyProtoT>

Enclosing class:

KeyTypeManager<KeyProtoT extends com.google.protobuf.MessageLite>

public abstract static class KeyTypeManager.KeyFactory<KeyFormatProtoT extends com.google.protobuf.MessageLite,KeyProtoT extends com.google.protobuf.MessageLite>
extends Object

A KeyFactory creates new keys from a given KeyFormat.

A KeyFactory implements all the methods which are required if a KeyTypeManager should also be able to generate keys. In particular, in this case it needs to have some KeyFormat protocol buffer which can be validated, parsed, and from which a key can be generated.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	KeyTypeManager.KeyFactory.KeyFormat<KeyFormatProtoT> A container that contains key format and other information that form key templates supported by this factory.

Constructor Summary

Constructors

Constructor and Description
KeyFactory(Class<KeyFormatProtoT> clazz)

Method Summary

Modifier and Type	Method and Description
abstract KeyProtoT	createKey(KeyFormatProtoT keyFormat) Creates a new key from a given format.
KeyProtoT	deriveKey(KeyFormatProtoT keyFormat, InputStream pseudoRandomness) Derives a new key from a given format, using the given pseudoRandomness.
Class<KeyFormatProtoT>	getKeyFormatClass() Returns the class corresponding to the key format protobuffer.
Map<String,KeyTypeManager.KeyFactory.KeyFormat<KeyFormatProtoT>>	keyFormats() Returns supported key formats and their names.
abstract KeyFormatProtoT	parseKeyFormat(com.google.protobuf.ByteString byteString) Parses a serialized key proto.
protected static void	readFully(InputStream input, byte[] output) Reads output.length number of bytes of (pseudo)randomness from the input stream into the provided output buffer.
abstract void	validateKeyFormat(KeyFormatProtoT keyFormatProto) Checks if the given keyFormatProto is a valid key.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyFactory

public KeyFactory(Class<KeyFormatProtoT> clazz)

Method Detail

getKeyFormatClass

public final Class<KeyFormatProtoT> getKeyFormatClass()

Returns the class corresponding to the key format protobuffer.

validateKeyFormat

public abstract void validateKeyFormat(KeyFormatProtoT keyFormatProto)
                                throws GeneralSecurityException

Checks if the given keyFormatProto is a valid key.

Throws:

GeneralSecurityException - if the passed keyFormatProto is not valid in any way.

parseKeyFormat

public abstract KeyFormatProtoT parseKeyFormat(com.google.protobuf.ByteString byteString)
                                        throws com.google.protobuf.InvalidProtocolBufferException

Parses a serialized key proto.

Implement as return KeyFormatProtoT.parseFrom(byteString);.

Throws:

com.google.protobuf.InvalidProtocolBufferException

createKey

public abstract KeyProtoT createKey(KeyFormatProtoT keyFormat)
                             throws GeneralSecurityException

Creates a new key from a given format.

Throws:

GeneralSecurityException

deriveKey

public KeyProtoT deriveKey(KeyFormatProtoT keyFormat,
                           InputStream pseudoRandomness)
                    throws GeneralSecurityException

Derives a new key from a given format, using the given pseudoRandomness.

Implementations need to note that the given paramter pseudoRandomness may only produce a finite amount of randomness. Hence, proper implementations will first obtain all the pseudorandom bytes needed; and only after produce the key.

While validateKeyFormat is called before this method will be called, implementations must check the version of the given keyFormat, as validateKeyFormat is also called from createKey.

Not every KeyTypeManager needs to implement this; if not implemented a GeneralSecurityException will be thrown.

Throws:

GeneralSecurityException

keyFormats

public Map<String,KeyTypeManager.KeyFactory.KeyFormat<KeyFormatProtoT>> keyFormats()
                                                                            throws GeneralSecurityException

Returns supported key formats and their names.

Throws:

GeneralSecurityException - Key type managers can throw GeneralSecurityException when their key formats depend on other key formats that were not registered.

readFully

protected static void readFully(InputStream input,
                                byte[] output)
                         throws IOException,
                                GeneralSecurityException

Reads output.length number of bytes of (pseudo)randomness from the input stream into the provided output buffer. Note that this method will not close the input stream.

Throws:

GeneralSecurityException - when not enough randomness was provided in the input stream.

IOException