/*
* Copyright [2007] [University Corporation for Advanced Internet Development, Inc.]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.opensaml.xml.signature.impl;
import org.opensaml.xml.security.CriteriaSet;
import org.opensaml.xml.security.SecurityException;
import org.opensaml.xml.security.credential.Credential;
import org.opensaml.xml.security.keyinfo.KeyInfoCredentialResolver;
import org.opensaml.xml.security.keyinfo.KeyInfoCriteria;
import org.opensaml.xml.signature.Signature;
import org.opensaml.xml.signature.SignatureTrustEngine;
import org.opensaml.xml.signature.SignatureValidator;
import org.opensaml.xml.util.DatatypeHelper;
import org.opensaml.xml.validation.ValidationException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A base implementation of {@link SignatureTrustEngine} which evaluates the validity and trustworthiness of XML and raw
* signatures.
*
* <p>
* When processing XML signatures, the supplied KeyInfoCredentialResolver will be used to resolve credential(s)
* containing the (advisory) signing key from the KeyInfo element of the Signature, if present. If any of these
* credentials do contain the valid signing key, they will be evaluated for trustworthiness against trusted information,
* which will be resolved in an implementation-specific manner.
*
* <p>
* Subclasses are required to implement {@link #evaluateTrust(Credential, Object)} using an implementation-specific
* trust model.
* </p>
*
* @param <TrustBasisType> the type of trusted information which has been resolved and which will serve as the basis for
* trust evaluation
*
*/
public abstract class BaseSignatureTrustEngine<TrustBasisType> implements SignatureTrustEngine {
/** Class logger. */
private final Logger log = LoggerFactory.getLogger(BaseSignatureTrustEngine.class);
/** KeyInfo credential resolver used to obtain the signing credential from a Signature's KeyInfo. */
private KeyInfoCredentialResolver keyInfoCredentialResolver;
/**
* Constructor.
*
* @param keyInfoResolver KeyInfo credential resolver used to obtain the (advisory) signing credential from a
* Signature's KeyInfo element.
*/
public BaseSignatureTrustEngine(KeyInfoCredentialResolver keyInfoResolver) {
if (keyInfoResolver == null) {
throw new IllegalArgumentException("KeyInfo credential resolver may not be null");
}
keyInfoCredentialResolver = keyInfoResolver;
}
/** {@inheritDoc} */
public KeyInfoCredentialResolver getKeyInfoResolver() {
return keyInfoCredentialResolver;
}
/**
* Attempt to establish trust by resolving signature verification credentials from the Signature's KeyInfo. If any
* credentials so resolved correctly verify the signature, attempt to establish trust using subclass-specific trust
* logic against trusted information as implemented in {@link #evaluateTrust(Credential, Object)}.
*
* @param signature the Signature to evaluate
* @param trustBasis the information which serves as the basis for trust evaluation
* @return true if the signature is verified by any KeyInfo-derived credential which can be established as trusted,
* otherwise false
* @throws SecurityException if an error occurs during signature verification or trust processing
*/
protected boolean validate(Signature signature, TrustBasisType trustBasis) throws SecurityException {
log.debug("Attempting to verify signature and establish trust using KeyInfo-derived credentials");
if (signature.getKeyInfo() != null) {
KeyInfoCriteria keyInfoCriteria = new KeyInfoCriteria(signature.getKeyInfo());
CriteriaSet keyInfoCriteriaSet = new CriteriaSet(keyInfoCriteria);
for (Credential kiCred : getKeyInfoResolver().resolve(keyInfoCriteriaSet)) {
if (verifySignature(signature, kiCred)) {
log.debug("Successfully verified signature using KeyInfo-derived credential");
log.debug("Attempting to establish trust of KeyInfo-derived credential");
if (evaluateTrust(kiCred, trustBasis)) {
log.debug("Successfully established trust of KeyInfo-derived credential");
return true;
} else {
log.debug("Failed to establish trust of KeyInfo-derived credential");
}
}
}
} else {
log.debug("Signature contained no KeyInfo element, could not resolve verification credentials");
}
log.debug("Failed to verify signature and/or establish trust using any KeyInfo-derived credentials");
return false;
}
/**
* Evaluate the untrusted KeyInfo-derived credential with respect to the specified trusted information.
*
* @param untrustedCredential the untrusted credential being evaluated
* @param trustBasis the information which serves as the basis for trust evaluation
*
* @return true if the trust can be established for the untrusted credential, otherwise false
*
* @throws SecurityException if an error occurs during trust processing
*/
protected abstract boolean evaluateTrust(Credential untrustedCredential, TrustBasisType trustBasis)
throws SecurityException;
/**
* Attempt to verify a signature using the key from the supplied credential.
*
* @param signature the signature on which to attempt verification
* @param credential the credential containing the candidate validation key
* @return true if the signature can be verified using the key from the credential, otherwise false
*/
protected boolean verifySignature(Signature signature, Credential credential) {
SignatureValidator validator = new SignatureValidator(credential);
try {
validator.validate(signature);
} catch (ValidationException e) {
log.debug("Signature validation using candidate validation credential failed", e);
return false;
}
log.debug("Signature validation using candidate credential was successful");
return true;
}
/**
* Check the signature and credential criteria for required values.
*
* @param signature the signature to be evaluated
* @param trustBasisCriteria the set of trusted credential criteria
* @throws SecurityException thrown if required values are absent or otherwise invalid
*/
protected void checkParams(Signature signature, CriteriaSet trustBasisCriteria) throws SecurityException {
if (signature == null) {
throw new SecurityException("Signature was null");
}
if (trustBasisCriteria == null) {
throw new SecurityException("Trust basis criteria set was null");
}
if (trustBasisCriteria.isEmpty()) {
throw new SecurityException("Trust basis criteria set was empty");
}
}
/**
* Check the signature and credential criteria for required values.
*
* @param signature the signature to be evaluated
* @param content the data over which the signature was computed
* @param algorithmURI the signing algorithm URI which was used
* @param trustBasisCriteria the set of trusted credential criteria
* @throws SecurityException thrown if required values are absent or otherwise invalid
*/
protected void checkParamsRaw(byte[] signature, byte[] content, String algorithmURI, CriteriaSet trustBasisCriteria)
throws SecurityException {
if (signature == null || signature.length == 0) {
throw new SecurityException("Signature byte array was null or empty");
}
if (content == null || content.length == 0) {
throw new SecurityException("Content byte array was null or empty");
}
if (DatatypeHelper.isEmpty(algorithmURI)) {
throw new SecurityException("Signature algorithm was null or empty");
}
if (trustBasisCriteria == null) {
throw new SecurityException("Trust basis criteria set was null");
}
if (trustBasisCriteria.isEmpty()) {
throw new SecurityException("Trust basis criteria set was empty");
}
}
}