1 files changed, 155 insertions, 0 deletions
diff --git a/pkix/src/main/java/org/spongycastle/cms/jcajce/JceCMSMacCalculatorBuilder.java b/pkix/src/main/java/org/spongycastle/cms/jcajce/JceCMSMacCalculatorBuilder.java
new file mode 100644
index 00000000..d6097471
--- /dev/null
+++ b/pkix/src/main/java/org/spongycastle/cms/jcajce/JceCMSMacCalculatorBuilder.java
@@ -0,0 +1,155 @@
+package org.spongycastle.cms.jcajce;
+
+import java.io.OutputStream;
+import java.security.AlgorithmParameterGenerator;
+import java.security.AlgorithmParameters;
+import java.security.GeneralSecurityException;
+import java.security.Provider;
+import java.security.SecureRandom;
+import java.security.spec.AlgorithmParameterSpec;
+
+import javax.crypto.KeyGenerator;
+import javax.crypto.Mac;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.RC2ParameterSpec;
+
+import org.spongycastle.asn1.ASN1ObjectIdentifier;
+import org.spongycastle.asn1.pkcs.PKCSObjectIdentifiers;
+import org.spongycastle.asn1.x509.AlgorithmIdentifier;
+import org.spongycastle.cms.CMSException;
+import org.spongycastle.jcajce.io.MacOutputStream;
+import org.spongycastle.operator.GenericKey;
+import org.spongycastle.operator.MacCalculator;
+import org.spongycastle.operator.jcajce.JceGenericKey;
+
+public class JceCMSMacCalculatorBuilder
+{
+    private final ASN1ObjectIdentifier macOID;
+    private final int                  keySize;
+
+    private EnvelopedDataHelper helper = new EnvelopedDataHelper(new DefaultJcaJceExtHelper());
+    private SecureRandom random;
+
+    public JceCMSMacCalculatorBuilder(ASN1ObjectIdentifier macOID)
+    {
+        this(macOID, -1);
+    }
+
+    public JceCMSMacCalculatorBuilder(ASN1ObjectIdentifier macOID, int keySize)
+    {
+        this.macOID = macOID;
+        this.keySize = keySize;
+    }
+
+    public JceCMSMacCalculatorBuilder setProvider(Provider provider)
+    {
+        this.helper = new EnvelopedDataHelper(new ProviderJcaJceExtHelper(provider));
+
+        return this;
+    }
+
+    public JceCMSMacCalculatorBuilder setProvider(String providerName)
+    {
+        this.helper = new EnvelopedDataHelper(new NamedJcaJceExtHelper(providerName));
+
+        return this;
+    }
+
+    public JceCMSMacCalculatorBuilder setSecureRandom(SecureRandom random)
+    {
+        this.random = random;
+
+        return this;
+    }
+
+    public MacCalculator build()
+        throws CMSException
+    {
+        return new CMSMacCalculator(macOID, keySize, random);
+    }
+
+    private class CMSMacCalculator
+        implements MacCalculator
+    {
+        private SecretKey encKey;
+        private AlgorithmIdentifier algorithmIdentifier;
+        private Mac mac;
+        private SecureRandom random;
+
+        CMSMacCalculator(ASN1ObjectIdentifier macOID, int keySize, SecureRandom random)
+            throws CMSException
+        {
+            KeyGenerator keyGen = helper.createKeyGenerator(macOID);
+
+            if (random == null)
+            {
+                random = new SecureRandom();
+            }
+
+            this.random = random;
+
+            if (keySize < 0)
+            {
+                keyGen.init(random);
+            }
+            else
+            {
+                keyGen.init(keySize, random);
+            }
+
+            encKey = keyGen.generateKey();
+
+            AlgorithmParameterSpec paramSpec = generateParameterSpec(macOID, encKey);
+
+            algorithmIdentifier = helper.getAlgorithmIdentifier(macOID, paramSpec);
+            mac = helper.createContentMac(encKey, algorithmIdentifier);
+        }
+
+        public AlgorithmIdentifier getAlgorithmIdentifier()
+        {
+            return algorithmIdentifier;
+        }
+
+        public OutputStream getOutputStream()
+        {
+            return new MacOutputStream(mac);
+        }
+
+        public byte[] getMac()
+        {
+            return mac.doFinal();
+        }
+
+        public GenericKey getKey()
+        {
+            return new JceGenericKey(algorithmIdentifier, encKey);
+        }
+
+        protected AlgorithmParameterSpec generateParameterSpec(ASN1ObjectIdentifier macOID, SecretKey encKey)
+            throws CMSException
+        {
+            try
+            {
+                if (macOID.equals(PKCSObjectIdentifiers.RC2_CBC))
+                {
+                    byte[] iv = new byte[8];
+
+                    random.nextBytes(iv);
+
+                    return new RC2ParameterSpec(encKey.getEncoded().length * 8, iv);
+                }
+
+                AlgorithmParameterGenerator pGen = helper.createAlgorithmParameterGenerator(macOID);
+
+                AlgorithmParameters p = pGen.generateParameters();
+
+                return p.getParameterSpec(IvParameterSpec.class);
+            }
+            catch (GeneralSecurityException e)
+            {
+                return null;
+            }
+        }
+    }
+}