anon.crypto
Class MyDSASignature

java.lang.Object
  anon.crypto.MyDSASignature

All Implemented Interfaces:

IMySignature, ISignatureCreationAlgorithm, ISignatureVerificationAlgorithm

public final class MyDSASignature
extends java.lang.Object
implements IMySignature

Implements the DSA algorithm for signatures.

Field Summary

private org.bouncycastle.crypto.digests.SHA1Digest	m_Digest
private java.security.Key	m_initKey The key with that this algorithm has been initialised.
private org.bouncycastle.crypto.signers.DSASigner	m_SignatureAlgorithm
private static org.bouncycastle.asn1.x509.AlgorithmIdentifier	ms_identifier

Constructor Summary

MyDSASignature()

Method Summary

byte[]	decodeForXMLSignature(byte[] a_encodedSignature) Tries to decode a signature in a way as it would meet the W3C standard for DSA XML signature values.
(package private) static java.math.BigInteger[]	derDecode(byte[] encoding, int off, int len)
(package private) static byte[]	derEncode(java.math.BigInteger r, java.math.BigInteger s)
byte[]	encodeForXMLSignature(byte[] a_signature) Encodes a signature in a way it meets the W3C standard for DSA XML signature values.
org.bouncycastle.asn1.x509.AlgorithmIdentifier	getIdentifier() Returns the algorithm identifier (DSA with SHA1).
java.lang.String	getXMLSignatureAlgorithmReference() Returns http://www.w3.org/2000/09/xmldsig#dsa-sha1.
void	initSign(IMyPrivateKey k) Initialises the algorithm for signing.
void	initVerify(IMyPublicKey k) Initialises the algorithm for verifying.
byte[]	sign(byte[] bytesToSign) Signs a message and returns the signature.
boolean	verify(byte[] a_message, byte[] a_signature) Tests if the signature of a specified message is valid.
boolean	verify(byte[] a_message, int message_offset, int message_len, byte[] a_signature, int signature_offset, int signature_len) Tests if the signature of a specified message is valid.

Methods inherited from class java.lang.Object

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

Field Detail

ms_identifier

private static final org.bouncycastle.asn1.x509.AlgorithmIdentifier ms_identifier

m_SignatureAlgorithm

private org.bouncycastle.crypto.signers.DSASigner m_SignatureAlgorithm

m_Digest

private org.bouncycastle.crypto.digests.SHA1Digest m_Digest

m_initKey

private java.security.Key m_initKey

The key with that this algorithm has been initialised.

Constructor Detail

MyDSASignature

public MyDSASignature()

Method Detail

initVerify

public void initVerify(IMyPublicKey k)
                throws java.security.InvalidKeyException

Description copied from interface: IMySignature

Initialises the algorithm for verifying. This must be done before doing the verify operation. The general contract of this method is that it must check if the algorithm has previously been initialised with the given key. If yes the method does nothing to save resources.

Specified by:

initVerify in interface IMySignature

Parameters:

k - a public key

Throws:

java.security.InvalidKeyException - if the key is invalid

initSign

public void initSign(IMyPrivateKey k)
              throws java.security.InvalidKeyException

Description copied from interface: IMySignature

Initialises the algorithm for signing. This must be done before doing the sign operation. The general contract of this method is that it must check if the algorithm has previously been initialised with the given key. If yes the method does nothing to save resources.

Specified by:

initSign in interface IMySignature

Parameters:

k - a private key

Throws:

java.security.InvalidKeyException - if the key is invalid

verify

public boolean verify(byte[] a_message,
                      int message_offset,
                      int message_len,
                      byte[] a_signature,
                      int signature_offset,
                      int signature_len)

Description copied from interface: ISignatureVerificationAlgorithm

Tests if the signature of a specified message is valid.

Specified by:

verify in interface ISignatureVerificationAlgorithm

Parameters:

a_message - a message

message_offset - start of message

message_len - length of message

a_signature - a signature

signature_offset - start of signature

signature_len - length of signature

Returns:

true if the signature of a specified message is valid; false otherwiese

verify

public boolean verify(byte[] a_message,
                      byte[] a_signature)

Description copied from interface: IMySignature

Tests if the signature of a specified message is valid.

Specified by:

verify in interface IMySignature

Specified by:

verify in interface ISignatureVerificationAlgorithm

Parameters:

a_message - a message

a_signature - a signature

Returns:

true if the signature of a specified message is valid; false otherwiese

sign

public byte[] sign(byte[] bytesToSign)

Description copied from interface: IMySignature

Signs a message and returns the signature.

Specified by:

sign in interface IMySignature

Specified by:

sign in interface ISignatureCreationAlgorithm

Parameters:

bytesToSign - a message

Returns:

the signature that was created

getIdentifier

public org.bouncycastle.asn1.x509.AlgorithmIdentifier getIdentifier()

Returns the algorithm identifier (DSA with SHA1).

Specified by:

getIdentifier in interface ISignatureCreationAlgorithm

Specified by:

getIdentifier in interface ISignatureVerificationAlgorithm

Returns:

the algorithm identifier (DSA with SHA1)

encodeForXMLSignature

public byte[] encodeForXMLSignature(byte[] a_signature)

Encodes a signature in a way it meets the W3C standard for DSA XML signature values. Extracts the ASN.1 encoded values for r and s from a DER encoded byte array. ASN.1 Notation: sequence { integer r integer s } --> Der-Encoding byte 0x30 // Sequence byte 44 + x // len in bytes (x = {0|1|2} depending on r and s byte 0x02 // integer byte <= 21 // len of r (21: if first bit of r set, we need a leading 0 --> 20 + 1 bytes) byte[] ... // value of r (with leading zero if necessary) byte 0x02 // integer byte <= 21 // len of s (21: if first bit of s set, we need a leading 0 --> 20 + 1 bytes) byte[] ... // value of s (with leading zero if necessary)

Specified by:

encodeForXMLSignature in interface IMySignature

Specified by:

encodeForXMLSignature in interface ISignatureCreationAlgorithm

Parameters:

a_signature - an non-encoded signature in DER format

Returns:

the encoded signature in R-S-encoding or null if an error occured

See Also:

http://www.w3.org/TR/xmldsig-core/#sec-DSA

decodeForXMLSignature

public byte[] decodeForXMLSignature(byte[] a_encodedSignature)

Tries to decode a signature in a way as it would meet the W3C standard for DSA XML signature values. Making DER-Encoding of r and s..... ASN.1 Notation: sequence { integer r integer s } HINT: Sun JDK 1.4.x needs a leading '0' in the binary representation of r (and s) if r[0]>0x7F or s[0]>0x7F --> Der-Encoding 0x30 //Sequence 44 + x // len in bytes (x = {0|1|2} depending on r and s (see above) 0x02 // integer 20 | 21 // len in bytes of r .... //value of r (with leading zero if necessary) 0x02 //integer 20 | 21 //len of s ... value of s (with leading zero if necessary)

Specified by:

decodeForXMLSignature in interface IMySignature

Specified by:

decodeForXMLSignature in interface ISignatureVerificationAlgorithm

Parameters:

a_encodedSignature - an encoded signature in R-S format

Returns:

the decoded signature in DER format or null if an error occured

See Also:

http://www.w3.org/TR/xmldsig-core/#sec-DSA

getXMLSignatureAlgorithmReference

public java.lang.String getXMLSignatureAlgorithmReference()

Returns http://www.w3.org/2000/09/xmldsig#dsa-sha1.

Specified by:

getXMLSignatureAlgorithmReference in interface IMySignature

Specified by:

getXMLSignatureAlgorithmReference in interface ISignatureCreationAlgorithm

Specified by:

getXMLSignatureAlgorithmReference in interface ISignatureVerificationAlgorithm

Returns:

http://www.w3.org/2000/09/xmldsig#dsa-sha1

See Also:

http://www.w3.org/TR/xmldsig-core/#sec-AlgID

derEncode

static byte[] derEncode(java.math.BigInteger r,
                        java.math.BigInteger s)
                 throws java.io.IOException

Throws:

java.io.IOException

derDecode

static java.math.BigInteger[] derDecode(byte[] encoding,
                                        int off,
                                        int len)
                                 throws java.io.IOException

Throws:

java.io.IOException