All Known Subinterfaces:

EncryptableKeyChain

All Known Implementing Classes:

BasicKeyChain, DeterministicKeyChain, MarriedKeyChain
```
public interface KeyChain
```
A KeyChain is a class that stores a collection of keys for a Wallet. Key chains are expected to be able to look up keys given a hash (i.e. address) or pubkey bytes, and provide keys on request for a given purpose. They can inform event listeners about new keys being added.

However it is important to understand what this interface does not provide. It cannot encrypt or decrypt keys, for instance you need an implementor of EncryptableKeyChain. It cannot have keys imported into it, that you to use a method of a specific key chain instance, such as BasicKeyChain. The reason for these restrictions is to support key chains that may be handled by external hardware or software, or which are derived deterministically from a seed (and thus the notion of importing a key is meaningless).

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static class KeyChain.KeyPurpose

Method Summary

All Methods Instance Methods Abstract Methods Default Methods Deprecated Methods
Modifier and Type	Method	Description
`void`	`addEventListener(KeyChainEventListener listener)`	Adds a listener for events that are run when keys are added, on the user thread.
`void`	`addEventListener(KeyChainEventListener listener, java.util.concurrent.Executor executor)`	Adds a listener for events that are run when keys are added, on the given executor.
`java.time.Instant`	`earliestKeyCreationTime()`	Returns the earliest creation time of keys in this chain.
`default long`	`getEarliestKeyCreationTime()`	Deprecated. use `earliestKeyCreationTime()`
`BloomFilter`	`getFilter(int size, double falsePositiveRate, int tweak)`	Gets a bloom filter that contains all of the public keys from this chain, and which will provide the given false-positive rate if it has size elements.
`ECKey`	`getKey(KeyChain.KeyPurpose purpose)`	Obtains a key intended for the given purpose.
`java.util.List<? extends ECKey>`	`getKeys(KeyChain.KeyPurpose purpose, int numberOfKeys)`	Obtains a number of key/s intended for the given purpose.
`boolean`	`hasKey(ECKey key)`	Returns true if the given key is in the chain.
`int`	`numBloomFilterEntries()`	Returns the number of elements this chain wishes to insert into the Bloom filter.
`int`	`numKeys()`	Returns the number of keys this key chain manages.
`boolean`	`removeEventListener(KeyChainEventListener listener)`	Removes a listener for events that are run when keys are added.
`java.util.List<Protos.Key>`	`serializeToProtobuf()`	Return a list of keys serialized to the bitcoinj protobuf format.

- Method Detail
  - hasKey
```
boolean hasKey(ECKey key)
```
    Returns true if the given key is in the chain.
  - getKeys
```
java.util.List<? extends ECKey> getKeys(KeyChain.KeyPurpose purpose,
                                        int numberOfKeys)
```
    Obtains a number of key/s intended for the given purpose. The chain may create new key/s, derive, or re-use an old one.
  - getKey
```
ECKey getKey(KeyChain.KeyPurpose purpose)
```
    Obtains a key intended for the given purpose. The chain may create a new key, derive one, or re-use an old one.
  - serializeToProtobuf
```
java.util.List<Protos.Key> serializeToProtobuf()
```
    Return a list of keys serialized to the bitcoinj protobuf format.
    
    Returns:
    
    list of keys (treat as unmodifiable list)
  - addEventListener
```
void addEventListener(KeyChainEventListener listener)
```
    Adds a listener for events that are run when keys are added, on the user thread.
  - addEventListener
```
void addEventListener(KeyChainEventListener listener,
                      java.util.concurrent.Executor executor)
```
    Adds a listener for events that are run when keys are added, on the given executor.
  - removeEventListener
```
boolean removeEventListener(KeyChainEventListener listener)
```
    Removes a listener for events that are run when keys are added.
  - numKeys
```
int numKeys()
```
    Returns the number of keys this key chain manages.
  - numBloomFilterEntries
```
int numBloomFilterEntries()
```
    Returns the number of elements this chain wishes to insert into the Bloom filter. The size passed to getFilter(int, double, int) should be at least this large.
  - earliestKeyCreationTime
```
java.time.Instant earliestKeyCreationTime()
```
    Returns the earliest creation time of keys in this chain.
    
    Returns:
    
    earliest creation times of keys in this chain, Instant.EPOCH if at least one time is unknown, Instant.MAX if no keys in this chain
  - getEarliestKeyCreationTime
```
@Deprecated
default long getEarliestKeyCreationTime()
```
    Deprecated.
    use earliestKeyCreationTime()
  - getFilter
```
BloomFilter getFilter(int size,
                      double falsePositiveRate,
                      int tweak)
```
    Gets a bloom filter that contains all of the public keys from this chain, and which will provide the given false-positive rate if it has size elements. Keep in mind that you will get 2 elements in the bloom filter for each key in the key chain, for the public key and the hash of the public key (address form). For this reason size should be at least 2x the result of numKeys().
    
    This is used to generate a BloomFilter which can be BloomFilter.merge(BloomFilter)d with another. It could also be used if you have a specific target for the filter's size.
    
    See the docs for BloomFilter(int, double, int) for a brief explanation of anonymity when using bloom filters, and for the meaning of these parameters.

Interface KeyChain

Nested Class Summary

Method Summary

Method Detail

hasKey

getKeys

getKey

serializeToProtobuf

addEventListener

addEventListener

removeEventListener

numKeys

numBloomFilterEntries

earliestKeyCreationTime

getEarliestKeyCreationTime

getFilter