diff options
Diffstat (limited to 'libjava/java/security/SignedObject.java')
| -rw-r--r-- | libjava/java/security/SignedObject.java | 217 |
1 files changed, 139 insertions, 78 deletions
diff --git a/libjava/java/security/SignedObject.java b/libjava/java/security/SignedObject.java index 78684e5..6a8d612 100644 --- a/libjava/java/security/SignedObject.java +++ b/libjava/java/security/SignedObject.java @@ -1,5 +1,5 @@ /* SignedObject.java --- Signed Object Class - Copyright (C) 1999 Free Software Foundation, Inc. + Copyright (C) 1999, 2003, Free Software Foundation, Inc. This file is part of GNU Classpath. @@ -36,70 +36,123 @@ obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package java.security; + import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; +import java.io.ObjectInput; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; /** - SignedObject is used for storing rutime objects whose integrity - cannot be compromised without being detected. - - SignedObject contains a Serializable object which is yet to be - signed and its signature. - - The signed copy is a "deep copy" (in serialized form) of the - original object. Any changes to the original will not affect - the original. - - Several things to note are that, first there is no need to - initialize the signature engine as this class will handle that - automatically. Second, verification will only succeed if the - public key corresponds to the private key used to generate - the SignedObject. - - For fexibility, the signature engine can be specified in the - constructor or the verify method. The programmer who writes - code that verifies the SignedObject has not changed should be - aware of the Signature engine they use. A malicious Signature - may choose to always return true on verification and - bypass the secrity check. - - The GNU provider provides the NIST standard DSA which uses DSA - and SHA-1. It can be specified by SHA/DSA, SHA-1/DSA or its - OID. If the RSA signature algorithm is provided then - it could be MD2/RSA. MD5/RSA, or SHA-1/RSA. The algorithm must - be specified because there is no default. - - @author Mark Benvenuto <ivymccough@worldnet.att.net> - - @since JDK 1.2 + * <p><code>SignedObject</code> is a class for the purpose of creating authentic + * runtime objects whose integrity cannot be compromised without being detected. + * </p> + * + * <p>More specifically, a <code>SignedObject</code> contains another + * {@link Serializable} object, the (to-be-)signed object and its signature.</p> + * + * <p>The signed object is a <i>"deep copy"</i> (in serialized form) of an + * original object. Once the copy is made, further manipulation of the original + * object has no side effect on the copy.</p> + * + * <p>The underlying signing algorithm is designated by the {@link Signature} + * object passed to the constructor and the <code>verify()</code> method. A + * typical usage for signing is the following:</p> + * + * <pre> + * Signature signingEngine = Signature.getInstance(algorithm, provider); + * SignedObject so = new SignedObject(myobject, signingKey, signingEngine); + * </pre> + * + * <p>A typical usage for verification is the following (having received + * <code>SignedObject</code> so):</p> + * + * <pre> + * Signature verificationEngine = Signature.getInstance(algorithm, provider); + * if (so.verify(publickey, verificationEngine)) + * try + * { + * Object myobj = so.getObject(); + * } + * catch (ClassNotFoundException ignored) {}; + * </pre> + * + * <p>Several points are worth noting. First, there is no need to initialize the + * signing or verification engine, as it will be re-initialized inside the + * constructor and the <code>verify()</code> method. Secondly, for verification + * to succeed, the specified public key must be the public key corresponding to + * the private key used to generate the <code>SignedObject</code>.</p> + * + * <p>More importantly, for flexibility reasons, the <code>constructor</code> + * and <code>verify()</code> method allow for customized signature engines, + * which can implement signature algorithms that are not installed formally as + * part of a crypto provider. However, it is crucial that the programmer writing + * the verifier code be aware what {@link Signature} engine is being used, as + * its own implementation of the <code>verify()</code> method is invoked to + * verify a signature. In other words, a malicious {@link Signature} may choose + * to always return <code>true</code> on verification in an attempt to bypass a + * security check.</p> + * + * <p>The signature algorithm can be, among others, the NIST standard <i>DSS</i>, + * using <i>DSA</i> and <i>SHA-1</i>. The algorithm is specified using the same + * convention as that for signatures. The <i>DSA</i> algorithm using the + * </i>SHA-1</i> message digest algorithm can be specified, for example, as + * <code>"SHA/DSA"</code> or <code>"SHA-1/DSA"</code> (they are equivalent). In + * the case of <i>RSA</i>, there are multiple choices for the message digest + * algorithm, so the signing algorithm could be specified as, for example, + * <code>"MD2/RSA"</code>, <code>"MD5/RSA"</code> or <code>"SHA-1/RSA"</code>. + * The algorithm name must be specified, as there is no default.</p> + * + * <p>The name of the Cryptography Package Provider is designated also by the + * {@link Signature} parameter to the <code>constructor</code> and the <code> + * verify()</code> method. If the provider is not specified, the default + * provider is used. Each installation can be configured to use a particular + * provider as default.</p> + * + * <p>Potential applications of <code>SignedObject</code> include:</p> + * + * <ul> + * <li>It can be used internally to any Java runtime as an unforgeable + * authorization token -- one that can be passed around without the fear that + * the token can be maliciously modified without being detected.</li> + * <li>It can be used to sign and serialize data/object for storage outside the + * Java runtime (e.g., storing critical access control data on disk).</li> + * <li>Nested <i>SignedObjects</i> can be used to construct a logical sequence + * of signatures, resembling a chain of authorization and delegation.</li> + * </ul> + * + * @author Mark Benvenuto <ivymccough@worldnet.att.net> + * @since 1.2 + * @see Signature */ public final class SignedObject implements Serializable { static final long serialVersionUID = 720502720485447167L; + /** @serial */ private byte[] content; + /** @serial */ private byte[] signature; + /** @serial */ private String thealgorithm; /** - Constructs a new SignedObject from a Serializeable object. The - object is signed with private key and signature engine - - @param object the object to sign - @param signingKey the key to sign with - @param signingEngine the signature engine to use - - @throws IOException serialization error occurred - @throws InvalidKeyException invalid key - @throws SignatureException signing error + * Constructs a <code>SignedObject</code> from any {@link Serializable} + * object. The given object is signed with the given signing key, using the + * designated signature engine. + * + * @param object the object to be signed. + * @param signingKey the private key for signing. + * @param signingEngine the signature signing engine. + * @throws IOException if an error occurs during serialization. + * @throws InvalidKeyException if the key is invalid. + * @throws SignatureException if signing fails. */ public SignedObject(Serializable object, PrivateKey signingKey, - Signature signingEngine) throws IOException, - InvalidKeyException, SignatureException + Signature signingEngine) + throws IOException, InvalidKeyException, SignatureException { thealgorithm = signingEngine.getAlgorithm(); @@ -107,6 +160,7 @@ public final class SignedObject implements Serializable ObjectOutputStream p = new ObjectOutputStream(ostream); p.writeObject(object); p.flush(); + p.close(); content = ostream.toByteArray(); @@ -116,35 +170,39 @@ public final class SignedObject implements Serializable } /** - Returns the encapsulated object. The object is - de-serialized before being returned. - - @return the encapsulated object - - @throws IOException de-serialization error occurred - @throws ClassNotFoundException de-serialization error occurred + * Retrieves the encapsulated object. The encapsulated object is de-serialized + * before it is returned. + * + * @return the encapsulated object. + * @throws IOException if an error occurs during de-serialization. + * @throws ClassNotFoundException if an error occurs during de-serialization. */ public Object getObject() throws IOException, ClassNotFoundException { - ByteArrayInputStream istream = new ByteArrayInputStream(content); + ByteArrayInputStream bais = new ByteArrayInputStream(content); + ObjectInput oi = new ObjectInputStream(bais); + Object obj = oi.readObject(); + oi.close(); + bais.close(); - return new ObjectInputStream(istream).readObject(); + return obj; } /** - Returns the signature of the encapsulated object. - - @return a byte array containing the signature + * Retrieves the signature on the signed object, in the form of a byte array. + * + * @return a copy of the signature. */ public byte[] getSignature() { - return signature; + return (byte[]) signature.clone(); + } /** - Returns the name of the signature algorithm. - - @return the name of the signature algorithm. + * Retrieves the name of the signature algorithm. + * + * @return the signature algorithm name. */ public String getAlgorithm() { @@ -152,28 +210,31 @@ public final class SignedObject implements Serializable } /** - Verifies the SignedObject by checking that the signature that - this class contains for the encapsulated object. - - @param verificationKey the public key to use - @param verificationEngine the signature engine to use - - @return true if signature is correct, false otherwise - - @throws InvalidKeyException invalid key - @throws SignatureException signature verification failed + * Verifies that the signature in this <code>SignedObject</code> is the valid + * signature for the object stored inside, with the given verification key, + * using the designated verification engine. + * + * @param verificationKey the public key for verification. + * @param verificationEngine the signature verification engine. + * @return <code>true</code> if the signature is valid, <code>false</code> + * otherwise. + * @throws SignatureException if signature verification failed. + * @throws InvalidKeyException if the verification key is invalid. */ - public boolean verify(PublicKey verificationKey, - Signature verificationEngine) throws - InvalidKeyException, SignatureException + public boolean verify(PublicKey verificationKey, Signature verificationEngine) + throws InvalidKeyException, SignatureException { verificationEngine.initVerify(verificationKey); verificationEngine.update(content); return verificationEngine.verify(signature); } - // readObject is called to restore the state of the SignedObject from a - // stream. - //private void readObject(ObjectInputStream s) - // throws IOException, ClassNotFoundException + /** Called to restore the state of the SignedObject from a stream. */ + private void readObject(ObjectInputStream s) + throws IOException, ClassNotFoundException + { + s.defaultReadObject(); + content = (byte[]) content.clone(); + signature = (byte[]) signature.clone(); + } } |