001package com.nimbusds.jose.crypto;
002
003
004import java.util.Set;
005import javax.crypto.SecretKey;
006
007import com.nimbusds.jose.CriticalHeaderParamsAware;
008import com.nimbusds.jose.JOSEException;
009import com.nimbusds.jose.JWSHeader;
010import com.nimbusds.jose.JWSVerifier;
011import com.nimbusds.jose.jwk.OctetSequenceKey;
012import com.nimbusds.jose.util.Base64URL;
013import com.nimbusds.jose.util.StandardCharset;
014import net.jcip.annotations.ThreadSafe;
015
016
017/**
018 * Message Authentication Code (MAC) verifier of 
019 * {@link com.nimbusds.jose.JWSObject JWS objects}. Expects a secret key.
020 *
021 * <p>See RFC 7518
022 * <a href="https://tools.ietf.org/html/rfc7518#section-3.2">section 3.2</a>
023 * for more information.
024 *
025 * <p>This class is thread-safe.
026 *
027 * <p>Supports the following algorithms:
028 *
029 * <ul>
030 *     <li>{@link com.nimbusds.jose.JWSAlgorithm#HS256}
031 *     <li>{@link com.nimbusds.jose.JWSAlgorithm#HS384}
032 *     <li>{@link com.nimbusds.jose.JWSAlgorithm#HS512}
033 * </ul>
034 * 
035 * @author Vladimir Dzhuvinov
036 * @version 2016-06-26
037 */
038@ThreadSafe
039public class MACVerifier extends MACProvider implements JWSVerifier, CriticalHeaderParamsAware {
040
041
042        /**
043         * The critical header policy.
044         */
045        private final CriticalHeaderParamsDeferral critPolicy = new CriticalHeaderParamsDeferral();
046
047
048        /**
049         * Creates a new Message Authentication (MAC) verifier.
050         *
051         * @param secret The secret. Must be at least 256 bits long and not
052         *               {@code null}.
053         *
054         * @throws JOSEException If the secret length is shorter than the
055         *                       minimum 256-bit requirement.
056         */
057        public MACVerifier(final byte[] secret)
058                throws JOSEException {
059
060                this(secret, null);
061        }
062
063
064        /**
065         * Creates a new Message Authentication (MAC) verifier.
066         *
067         * @param secretString The secret as a UTF-8 encoded string. Must be at
068         *                     least 256 bits long and not {@code null}.
069         *
070         * @throws JOSEException If the secret length is shorter than the
071         *                       minimum 256-bit requirement.
072         */
073        public MACVerifier(final String secretString)
074                throws JOSEException {
075
076                this(secretString.getBytes(StandardCharset.UTF_8));
077        }
078
079
080        /**
081         * Creates a new Message Authentication (MAC) verifier.
082         *
083         * @param secretKey The secret key. Must be at least 256 bits long and
084         *                  not {@code null}.
085         *
086         * @throws JOSEException If the secret length is shorter than the
087         *                       minimum 256-bit requirement.
088         */
089        public MACVerifier(final SecretKey secretKey)
090                throws JOSEException {
091
092                this(secretKey.getEncoded());
093        }
094
095
096        /**
097         * Creates a new Message Authentication (MAC) verifier.
098         *
099         * @param jwk The secret as a JWK. Must be at least 256 bits long and
100         *            not {@code null}.
101         *
102         * @throws JOSEException If the secret length is shorter than the
103         *                       minimum 256-bit requirement.
104         */
105        public MACVerifier(final OctetSequenceKey jwk)
106                throws JOSEException {
107
108                this(jwk.toByteArray());
109        }
110
111
112        /**
113         * Creates a new Message Authentication (MAC) verifier.
114         *
115         * @param secret         The secret. Must be at least 256 bits long
116         *                       and not {@code null}.
117         * @param defCritHeaders The names of the critical header parameters
118         *                       that are deferred to the application for
119         *                       processing, empty set or {@code null} if none.
120         *
121         * @throws JOSEException If the secret length is shorter than the
122         *                       minimum 256-bit requirement.
123         */
124        public MACVerifier(final byte[] secret,
125                           final Set<String> defCritHeaders)
126                throws JOSEException {
127
128                super(secret, SUPPORTED_ALGORITHMS);
129
130                critPolicy.setDeferredCriticalHeaderParams(defCritHeaders);
131        }
132
133
134        @Override
135        public Set<String> getProcessedCriticalHeaderParams() {
136
137                return critPolicy.getProcessedCriticalHeaderParams();
138        }
139
140
141        @Override
142        public Set<String> getDeferredCriticalHeaderParams() {
143
144                return critPolicy.getProcessedCriticalHeaderParams();
145        }
146
147
148        @Override
149        public boolean verify(final JWSHeader header,
150                              final byte[] signedContent, 
151                              final Base64URL signature)
152                throws JOSEException {
153
154                if (! critPolicy.headerPasses(header)) {
155                        return false;
156                }
157
158                String jcaAlg = getJCAAlgorithmName(header.getAlgorithm());
159                byte[] expectedHMAC = HMAC.compute(jcaAlg, getSecret(), signedContent, getJCAContext().getProvider());
160                return ConstantTimeUtils.areEqual(expectedHMAC, signature.decode());
161        }
162}