Package convex.core.data

Class SignedData<T extends ACell>

java.lang.Object

convex.core.data.AObject

convex.core.data.ACell

convex.core.data.SignedData<T>

Type Parameters:

T - The type of the signed object

All Implemented Interfaces:

IValidated, IWriteable

public class SignedData<T extends ACell>
extends ACell

Node representing a signed data object. A signed data object encapsulates:

• An Address that identifies the signer
• A digital signature
• An underlying Cell that has been signed.

The SignedData instance is considered valid if the signature can be successfully validated for the given Address and data value, and if so can be taken as a cryptographic proof that the signature was created by someone in possession of the corresponding private key. Note we currently go via a Ref here for a few reasons: - It guarantees we have a hash for signing - It makes the SignedData object implementation/representation independent of the value type - It creates a possibility of structural sharing for transaction values excluding signatures Binary representation:

1. 1 byte - Tag.SIGNED_DATA tag
2. 32 bytes - Public Key of signer
3. 64 bytes - raw Signature data
4. 1+ bytes - Data Value Ref (may be embedded)

SECURITY: signing requires presence of a local keypair TODO: SECURITY: any persistence forces validation of Signature??

Field Summary

Fields inherited from class convex.core.data.ACell

cachedRef, EMPTY_ARRAY

Fields inherited from class convex.core.data.AObject

encoding

Method Summary

Modifier and Type	Method	Description
boolean	checkSignature()	Validates the signature in this SignedData instance.
static SignedData<ATransaction>	create(AKeyPair kp, ASignature sig, Ref<ATransaction> ref)
static <T extends ACell> SignedData<T>	create(AKeyPair keyPair, T value2)
static <T extends ACell> SignedData<T>	create(AccountKey address, ASignature sig, Ref<T> ref)	Creates a SignedData object with the given parameters.
static <T extends ACell> SignedData<T>	createWithRef(AKeyPair keyPair, Ref<T> ref)	Signs a data value Ref with the given keypair.
int	encode(byte[] bs, int pos)	Writes this Cell's encoding to a byte array, including a tag byte which will be written first.
int	encodeRaw(byte[] bs, int pos)	Writes this Cell's encoding to a byte array, excluding the tag byte.
int	estimatedEncodingSize()	Estimate the encoded data size for this Cell.
AccountKey	getAccountKey()	Gets the public key of the signer.
Ref<T>	getDataRef()
<R extends ACell> Ref<R>	getRef(int i)	Gets a numbered child Ref from within this Cell.
int	getRefCount()	Gets the number of Refs contained within this Cell.
ASignature	getSignature()	Gets the Signature that formed part of this SignedData object
byte	getTag()	Gets the tag byte for this cell.
T	getValue()	Gets the signed value object encapsulated by this SignedData object.
boolean	isCanonical()	Returns true if this Cell is in a canonical representation for message writing.
final boolean	isCVMValue()	Returns true if this Cell represents a first class CVM Value.
boolean	isEmbedded()	SignedData is not embedded.
boolean	isSignatureChecked()	Checks if the signature has already gone through verification.
boolean	print(BlobBuilder bb, long limit)	Prints this Object to a readable String Representation.
static <T extends ACell> SignedData<T>	read(ByteBuffer data)	Reads a SignedData instance from the given ByteBuffer
ACell	toCanonical()	Converts this Cell to its canonical version.
String	toString()	Returns the Java String representation of this Cell.
SignedData<T>	updateRefs(IRefFunction func)	Updates all Refs in this object using the given function.
void	validate()	Validates the complete structure of this object.
void	validateCell()	Validates the local structure and invariants of this cell.
void	validateSignature()

Methods inherited from class convex.core.data.ACell

announce, announce, attachMemorySize, attachRef, cachedEncoding, cachedHash, calcMemorySize, createAnnounced, createEncoding, createPersisted, createPersisted, createRef, equals, equals, getCanonical, getChildRefs, getEncoding, getEncodingLength, getHash, getMemorySize, getRef, getType, hashCode, isCompletelyEncoded, mark, mark, toCVMString, write

Methods inherited from class convex.core.data.AObject

attachEncoding, print, print

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Details

createWithRef

public static <T extends ACell> SignedData<T> createWithRef(AKeyPair keyPair,
 Ref<T> ref)

Signs a data value Ref with the given keypair. SECURITY: Marks as already validated, since we just signed it.

Parameters:

keyPair - The public/private key pair of the signer.

ref - Ref to the data to sign

Returns:

SignedData object signed with the given key-pair

create

public static <T extends ACell> SignedData<T> create(AKeyPair keyPair,
 T value2)

create

public static <T extends ACell> SignedData<T> create(AccountKey address,
 ASignature sig,
 Ref<T> ref)

Creates a SignedData object with the given parameters. SECURITY: Not assumed to be valid.

Parameters:

address - Public Address of the signer

sig - Signature of the supplied data

ref - Ref to the data that has been signed

Returns:

A new SignedData object

create

public static SignedData<ATransaction> create(AKeyPair kp,
 ASignature sig,
 Ref<ATransaction> ref)

getValue

public T getValue()

Gets the signed value object encapsulated by this SignedData object. Does not check Signature.

Returns:

Data value that has been signed

getAccountKey

public AccountKey getAccountKey()

Gets the public key of the signer. If the signature is valid, this represents a cryptographic proof that the signer was in possession of the private key of this address.

Returns:

Public Key of signer.

getSignature

public ASignature getSignature()

Gets the Signature that formed part of this SignedData object

Returns:

Signature instance

encode

public int encode(byte[] bs,
 int pos)

Description copied from class: ACell

Writes this Cell's encoding to a byte array, including a tag byte which will be written first. Cell must be canonical, or else an error may occur.

Specified by:

encode in interface IWriteable

Specified by:

encode in class ACell

Parameters:

bs - A byte array to which to write the encoding

pos - The offset into the byte array

Returns:

New position after writing

encodeRaw

public int encodeRaw(byte[] bs,
 int pos)

Description copied from class: ACell

Writes this Cell's encoding to a byte array, excluding the tag byte.

Specified by:

encodeRaw in class ACell

Parameters:

bs - A byte array to which to write the encoding

pos - The offset into the byte array

Returns:

New position after writing

estimatedEncodingSize

public int estimatedEncodingSize()

Description copied from interface: IWriteable

Estimate the encoded data size for this Cell. Used for quickly sizing buffers. Implementations should try to return a size that is likely to contain the entire object when represented in binary format, including the tag byte.

Returns:

The estimated size for the binary representation of this object.

read

public static <T extends ACell> SignedData<T> read(ByteBuffer data)
                                            throws BadFormatException

Reads a SignedData instance from the given ByteBuffer

Parameters:

data - A ByteBuffer containing

Returns:

A SignedData object

Throws:

BadFormatException - If encoding is invalid

checkSignature

public boolean checkSignature()

Validates the signature in this SignedData instance. Caches result

Returns:

true if valid, false otherwise

isSignatureChecked

public boolean isSignatureChecked()

Checks if the signature has already gone through verification. MAy or may not be a valid signature.

Returns:

true if valid, false otherwise

validateSignature

public void validateSignature()
                       throws BadSignatureException

Throws:

BadSignatureException

isCanonical

public boolean isCanonical()

Description copied from class: ACell

Returns true if this Cell is in a canonical representation for message writing. Non-canonical objects may be used on a temporary internal basis, they must always be converted to canonical representations for external use (e.g. Encoding).

Specified by:

isCanonical in class ACell

Returns:

true if the object is in canonical format, false otherwise

isCVMValue

public final boolean isCVMValue()

Description copied from class: ACell

Returns true if this Cell represents a first class CVM Value. Sub-structural cells that are not themselves first class values should return false, pretty much everything else should return true. Note: CVM values might not be in a canonical format, e.g. temporary data structures

Specified by:

isCVMValue in class ACell

Returns:

true if the object is a CVM Value, false otherwise

getRefCount

public int getRefCount()

Description copied from class: ACell

Gets the number of Refs contained within this Cell. This number is final / immutable for any given instance and is defined by the Cell encoding rules. Contained Refs may be either external or embedded.

Specified by:

getRefCount in class ACell

Returns:

The number of Refs in this Cell

getRef

public <R extends ACell> Ref<R> getRef(int i)

Description copied from class: ACell

Gets a numbered child Ref from within this Cell.

Overrides:

getRef in class ACell

Type Parameters:

R - Type of referenced Cell

Parameters:

i - Index of ref to get

Returns:

The Ref at the specified index

updateRefs

public SignedData<T> updateRefs(IRefFunction func)

Description copied from class: ACell

Updates all Refs in this object using the given function. The function *must not* change the hash value of Refs, in order to ensure structural integrity of modified data structures. This is a building block for a very sneaky trick that enables use to do a lot of efficient operations on large trees of smart references. Must return the same object if no Refs are altered.

Overrides:

updateRefs in class ACell

Parameters:

func - Ref update function

Returns:

Cell with updated Refs

print

public boolean print(BlobBuilder bb,
 long limit)

Description copied from class: AObject

Prints this Object to a readable String Representation. SECURITY: Must halt and return false in O(1) time if limit of printing is exceeded otherwise DoS attacks may be possible.

Specified by:

print in class AObject

Parameters:

bb - BlobBuilder to append to

limit - Limit of printing in string bytes

Returns:

True if fully printed within limit, false otherwise

validate

public void validate()
              throws InvalidDataException

Description copied from interface: IValidated

Validates the complete structure of this object. It is necessary to ensure all child Refs are validated, so the general contract for validate is:

1. Call super.validate() - which will indirectly call validateCell()
2. Call validate() on any contained cells in this class

Specified by:

validate in interface IValidated

Overrides:

validate in class ACell

Throws:

InvalidDataException - If the data Value is invalid in any way

validateCell

public void validateCell()
                  throws InvalidDataException

Description copied from class: ACell

Validates the local structure and invariants of this cell. Called by validate() super implementation. Should validate directly contained data, but should not validate all other structure of this cell. In particular, should not traverse potentially missing child Refs.

Specified by:

validateCell in class ACell

Throws:

InvalidDataException - If the Cell is invalid

getDataRef

public Ref<T> getDataRef()

isEmbedded

public boolean isEmbedded()

SignedData is not embedded. We want to persist in store always to cache verification status

Overrides:

isEmbedded in class ACell

Returns:

Always false

toString

public String toString()

Description copied from class: ACell

Returns the Java String representation of this Cell. The String representation is intended to be a easy-to-read textual representation of the Cell's data content.

Overrides:

toString in class ACell

getTag

public byte getTag()

Description copied from class: ACell

Gets the tag byte for this cell. The tag byte is always written as the first byte of the Cell's Encoding

Specified by:

getTag in class ACell

Returns:

Tag byte for this Cell

toCanonical

public ACell toCanonical()

Description copied from class: ACell

Converts this Cell to its canonical version. Returns this Cell if already canonical, may be O(n) in size of value otherwise.

Specified by:

toCanonical in class ACell

Returns:

Canonical version of Cell