com.google.bitcoin.core

Class ECKey.ECDSASignature

java.lang.Object

com.google.bitcoin.core.ECKey.ECDSASignature

Direct Known Subclasses:

TransactionSignature

Enclosing class:

ECKey

public static class ECKey.ECDSASignature
extends Object

Groups the two components that make up a signature, and provides a way to encode to DER form, which is how ECDSA signatures are represented when embedded in other data structures in the Bitcoin protocol. The raw components can be useful for doing further EC maths on them.

Field Summary

Fields

Modifier and Type	Field and Description
BigInteger	r The two components of the signature.
BigInteger	s The two components of the signature.

Constructor Summary

Constructors

Constructor and Description
ECKey.ECDSASignature(BigInteger r, BigInteger s) Constructs a signature with the given components.

Method Summary

Methods

Modifier and Type	Method and Description
static ECKey.ECDSASignature	decodeFromDER(byte[] bytes)
protected ByteArrayOutputStream	derByteStream()
byte[]	encodeToDER() DER is an international standard for serializing data structures which is widely used in cryptography.
void	ensureCanonical() Will automatically adjust the S component to be less than or equal to half the curve order, if necessary.

Methods inherited from class java.lang.Object

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

Field Detail

r

public BigInteger r

The two components of the signature.

s

public BigInteger s

The two components of the signature.

Constructor Detail

ECKey.ECDSASignature

public ECKey.ECDSASignature(BigInteger r,
                    BigInteger s)

Constructs a signature with the given components. Does NOT automatically canonicalise the signature.

Method Detail

ensureCanonical

public void ensureCanonical()

Will automatically adjust the S component to be less than or equal to half the curve order, if necessary. This is required because for every signature (r,s) the signature (r, -s (mod N)) is a valid signature of the same message. However, we dislike the ability to modify the bits of a Bitcoin transaction after it's been signed, as that violates various assumed invariants. Thus in future only one of those forms will be considered legal and the other will be banned.

encodeToDER

public byte[] encodeToDER()

DER is an international standard for serializing data structures which is widely used in cryptography. It's somewhat like protocol buffers but less convenient. This method returns a standard DER encoding of the signature, as recognized by OpenSSL and other libraries.

decodeFromDER

public static ECKey.ECDSASignature decodeFromDER(byte[] bytes)

derByteStream

protected ByteArrayOutputStream derByteStream()
                                       throws IOException

Throws:

IOException