spki
Class PublicKey

java.lang.Object
  |
  +--spki.BaseObj
        |
        +--spki.PublicKey

public class PublicKey

extends BaseObj

implements Key, Principal, SeqDefValue

This class represents a public signature key object. It provides everything a user needs to employ the key for checking signatures.

A collision-free hash of the SList canonical representation of an instance of this object yields a SPKI global identifier (and so does the SList itself, but a hash is much smaller). This can be done by calling the getKeyHash() method. An alternative is to use just the Base64-encoded hash value returned by the getKeyId() method.

Formal definition:

 <alg-id>:: <byte-string> | <uri> ;
 <pub-sig-alg-id>:: <alg-id> ;
 <pub-key>:: "(" "public-key" "(" <pub-sig-alg-id> <s-expr>+ ")" ")" ;
 

The RSA-keys S-Expression must contain the following s-expressions tokens: n and e, of the form (<token> <keydata>).

It also interfaces with the [I]JCA ([International] Java Cryptography Architecture) where possible, which means that we can use crypto-packages such as Systemic's Cryptix, which we do. This has some consequences for the signatures generated.

NOTE: For now, only String is supported for the algorithm-id. NOTE: only rsa-pkcs1-sha1 is supported for now.

TODO: support using URI as the algorithm-id?

Version:

$Id: PublicKey.java,v 1.20 2002/06/25 12:12:28 tep Exp $

Author:

Tep Narula <tep@win.trlabs.ca>, adapted from SPKI.SPKIPublicKey by Per Harald Myrvang <perm@pasta.cs.uit.no>

See Also:

Signature

Field Summary

private static String	__ME This class's full name.
private String	cachedKeyId Cached key-id.
private PublicKey	jca_key The key, used by JCA.
private Hash	keyhash Hash of the public key.
static String	SEXP_NAME This class S-Expression type name, used by toSExpression() and other methods.
private Signature	sig Signature object used for verification.
private String	sig_alg_id Signature algorithm-id.
private String	signature_provider Signature Provider ID.

Fields inherited from class spki.BaseObj

__ME, cache_sexp, cached_sexp, DEFAULT_HASH_ALG, locked, SEXP_NAME

Constructor Summary

private	PublicKey() Don't use me!
	PublicKey(PublicKey pk) Create an immutable PublicKey from a java.security.PublicKey object.
	PublicKey(SExpression sexp) Create an immutable PublicKey object from an S-Expression.

Method Summary

boolean	equals(Principal that) Compare this object with another principal.
String	getAlgId() Get the SPKI encryption/signature algorithm id associated with the key.
Key	getJCAKey() Get a key object usable by [I]JCA packages.
Hash	getKeyHash() Get a Hash representing this key using the default hash algorithm.
Hash	getKeyHash(String hashAlg) Get a Hash representing this key using the specified hashing algorithm.
String	getKeyId() Get the key-id of this key.
Principal	toHashPrincipal() Convert this principal into a hash representation.
SExpression	toSExpression() Build an SExpression representing this object.
boolean	verify(byte[] input, byte[] sig_params) Verify a given input against a given signature using this public key.
boolean	verify(Hash hash, byte[] sig_params) Verify a given Hash object against a given signature value with this public key.
boolean	verify(Signature sig) Verify a given Signature using this public key.

Methods inherited from class spki.BaseObj

disableSExpressionCaching, enableSExpressionCaching, extractHashAlgId, getCachedSExpression, isLocked, isSListOfType, lock, providerToSPKI, setCachedSExpression, spkiToProvider, toString

Methods inherited from class java.lang.Object

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

Field Detail

__ME

private static final String __ME

This class's full name.

SEXP_NAME

public static final String SEXP_NAME

This class S-Expression type name, used by toSExpression() and other methods.

jca_key

private PublicKey jca_key

The key, used by JCA.

sig_alg_id

private String sig_alg_id

Signature algorithm-id.

signature_provider

private String signature_provider

Signature Provider ID.

sig

private Signature sig

Signature object used for verification.

keyhash

private Hash keyhash

Hash of the public key.

cachedKeyId

private String cachedKeyId

Cached key-id.

See Also:

getKeyId()

Constructor Detail

PublicKey

private PublicKey()

Don't use me!

See Also:

PublicKey(SExpression), PublicKey(java.security.PublicKey)

PublicKey

public PublicKey(SExpression sexp)
          throws SPKIException,
                 ParseException

Create an immutable PublicKey object from an S-Expression.

See Also:

BaseObj.BaseObj(SExpression)

PublicKey

public PublicKey(PublicKey pk)
          throws SPKIException

Create an immutable PublicKey from a java.security.PublicKey object. Note that the public signature algorithm id (<pub-sig-alg-id>) defaults in the case of RSA to rsa-pkcs1-sha1.

Parameters:

pk - Object implementing the java.security.PublicKey interface.

Throws:

SPKIException - if something went wrong.

Method Detail

toSExpression

public SExpression toSExpression()
                          throws SPKIException

Description copied from interface: SPKIObject

Build an SExpression representing this object.

Overrides:

toSExpression in class BaseObj

Tags copied from interface: SPKIObject

Returns:

SExpression object representing this object, or null.

Throws:

SPKIException - if something went wrong during conversion.

getAlgId

public String getAlgId()

Description copied from interface: Key

Get the SPKI encryption/signature algorithm id associated with the key.

Specified by:

getAlgId in interface Key

Tags copied from interface: Key

Returns:

String containing a SPKI algorithm-id.

getJCAKey

public Key getJCAKey()

Description copied from interface: Key

Get a key object usable by [I]JCA packages.

Specified by:

getJCAKey in interface Key

Tags copied from interface: Key

Returns:

java.security.Key object implementing, or null if this is a private key.

getKeyHash

public Hash getKeyHash()
                throws SPKIException

Description copied from interface: Key

Get a Hash representing this key using the default hash algorithm.

Specified by:

getKeyHash in interface Key

Tags copied from interface: Key

Returns:

Hash object representing this key.

Throws:

SPKIException - if something went wrong

getKeyHash

public Hash getKeyHash(String hashAlg)
                throws SPKIException

Get a Hash representing this key using the specified hashing algorithm. The Hash object is cached at first call, but if a subsequent call specifies a different hashing algorithm, then it caches and returns a new Hash object created with the specified algorithm.

Specified by:

getKeyHash in interface Key

Parameters:

hashAlg - hashing algorithm-id (currently "sha1" or "md5").

See Also:

Key.getKeyHash(String)

getKeyId

public String getKeyId()
                throws SPKIException

Description copied from interface: Key

Get the key-id of this key. Key-id is a Base64-encoded hash value, using the default hash algorithm.

Specified by:

getKeyId in interface Key

Tags copied from interface: Key

Returns:

String containing the key-id, or null.

Throws:

SPKIException - if something went wrong

equals

public boolean equals(Principal that)

Description copied from interface: Principal

Compare this object with another principal.

Specified by:

equals in interface Principal

Tags copied from interface: Principal

Parameters:

that - a principal to compare with.

Returns:

true if the two principals are equal, false otherwise.

toHashPrincipal

public Principal toHashPrincipal()
                          throws SPKIException

Description copied from interface: Principal

Convert this principal into a hash representation.

Specified by:

toHashPrincipal in interface Principal

Tags copied from interface: Principal

Returns:

the hash representation of this principal.

Throws:

SPKIException - if something went wrong during conversion.

verify

public boolean verify(Hash hash,
                      byte[] sig_params)
               throws SPKIException

Verify a given Hash object against a given signature value with this public key.

Parameters:

hash - the Hash object to be verified.

sig_params - the signature value to verify against the hash.

Returns:

true if the signature verified, false if not.

Throws:

SPKIException - if something went wrong.

verify

public boolean verify(byte[] input,
                      byte[] sig_params)
               throws SPKIException

Verify a given input against a given signature using this public key. It simply hashes the input byte-array and calls the verify(Hash,byte[]) method.

Parameters:

input - the data byte-array to be verified.

sig_params - the signature value to verify against the input.

Returns:

true if the signature verified, false if not.

Throws:

SPKIException - if something went wrong.

See Also:

verify(Hash,byte[])

verify

public boolean verify(Signature sig)
               throws SPKIException

Verify a given Signature using this public key. It's simply a front-end to the verify(Hash,byte[]) method.

Parameters:

sig - the Signature object to be verified.

Returns:

true if the Signature verified, false if not.

Throws:

SPKIException - if something went wrong.

See Also:

verify(Hash,byte[])