1 files changed, 122 insertions, 0 deletions

diff --git a/pkix/src/main/java/org/spongycastle/cms/PasswordRecipientInfoGenerator.java b/pkix/src/main/java/org/spongycastle/cms/PasswordRecipientInfoGenerator.java
new file mode 100644
index 00000000..33c34b7a
--- /dev/null
+++ b/pkix/src/main/java/org/spongycastle/cms/PasswordRecipientInfoGenerator.java
@@ -0,0 +1,122 @@
+package org.spongycastle.cms;
+
+import java.security.SecureRandom;
+
+import org.spongycastle.asn1.ASN1EncodableVector;
+import org.spongycastle.asn1.ASN1ObjectIdentifier;
+import org.spongycastle.asn1.ASN1OctetString;
+import org.spongycastle.asn1.DEROctetString;
+import org.spongycastle.asn1.DERSequence;
+import org.spongycastle.asn1.cms.PasswordRecipientInfo;
+import org.spongycastle.asn1.cms.RecipientInfo;
+import org.spongycastle.asn1.pkcs.PBKDF2Params;
+import org.spongycastle.asn1.pkcs.PKCSObjectIdentifiers;
+import org.spongycastle.asn1.x509.AlgorithmIdentifier;
+import org.spongycastle.operator.GenericKey;
+
+public abstract class PasswordRecipientInfoGenerator
+    implements RecipientInfoGenerator
+{
+    private char[] password;
+    private AlgorithmIdentifier keyDerivationAlgorithm;
+    private ASN1ObjectIdentifier kekAlgorithm;
+    private SecureRandom random;
+    private int schemeID;
+    private int keySize;
+    private int blockSize;
+
+    protected PasswordRecipientInfoGenerator(ASN1ObjectIdentifier kekAlgorithm, char[] password)
+    {
+        this(kekAlgorithm, password, getKeySize(kekAlgorithm), ((Integer)PasswordRecipientInformation.BLOCKSIZES.get(kekAlgorithm)).intValue());
+    }
+
+    protected PasswordRecipientInfoGenerator(ASN1ObjectIdentifier kekAlgorithm, char[] password, int keySize, int blockSize)
+    {
+        this.password = password;
+        this.schemeID = PasswordRecipient.PKCS5_SCHEME2_UTF8;
+        this.kekAlgorithm = kekAlgorithm;
+        this.keySize = keySize;
+        this.blockSize = blockSize;
+    }
+
+    private static int getKeySize(ASN1ObjectIdentifier kekAlgorithm)
+    {
+        Integer size = (Integer)PasswordRecipientInformation.KEYSIZES.get(kekAlgorithm);
+
+        if (size == null)
+        {
+            throw new IllegalArgumentException("cannot find key size for algorithm: " +  kekAlgorithm);
+        }
+
+        return size.intValue();
+    }
+
+    public PasswordRecipientInfoGenerator setPasswordConversionScheme(int schemeID)
+    {
+        this.schemeID = schemeID;
+
+        return this;
+    }
+
+    public PasswordRecipientInfoGenerator setSaltAndIterationCount(byte[] salt, int iterationCount)
+    {
+        this.keyDerivationAlgorithm = new AlgorithmIdentifier(PKCSObjectIdentifiers.id_PBKDF2, new PBKDF2Params(salt, iterationCount));
+
+        return this;
+    }
+
+    public PasswordRecipientInfoGenerator setSecureRandom(SecureRandom random)
+    {
+        this.random = random;
+
+        return this;
+    }
+
+    public RecipientInfo generate(GenericKey contentEncryptionKey)
+        throws CMSException
+    {
+        byte[] iv = new byte[blockSize];     /// TODO: set IV size properly!
+
+        if (random == null)
+        {
+            random = new SecureRandom();
+        }
+        
+        random.nextBytes(iv);
+
+        if (keyDerivationAlgorithm == null)
+        {
+            byte[] salt = new byte[20];
+
+            random.nextBytes(salt);
+
+            keyDerivationAlgorithm = new AlgorithmIdentifier(PKCSObjectIdentifiers.id_PBKDF2, new PBKDF2Params(salt, 1024));
+        }
+
+        byte[] encodedPassword = CMSUtils.getPasswordBytes(schemeID, password);
+
+        byte[] derivedKey = calculateDerivedKey(encodedPassword, keyDerivationAlgorithm, keySize);
+
+        AlgorithmIdentifier kekAlgorithmId = new AlgorithmIdentifier(kekAlgorithm, new DEROctetString(iv));
+
+        byte[] encryptedKeyBytes = generateEncryptedBytes(kekAlgorithmId, derivedKey, contentEncryptionKey);
+
+        ASN1OctetString encryptedKey = new DEROctetString(encryptedKeyBytes);
+
+        ASN1EncodableVector v = new ASN1EncodableVector();
+        v.add(kekAlgorithm);
+        v.add(new DEROctetString(iv));
+
+        AlgorithmIdentifier keyEncryptionAlgorithm = new AlgorithmIdentifier(
+            PKCSObjectIdentifiers.id_alg_PWRI_KEK, new DERSequence(v));
+
+        return new RecipientInfo(new PasswordRecipientInfo(keyDerivationAlgorithm,
+            keyEncryptionAlgorithm, encryptedKey));
+    }
+
+    protected abstract byte[] calculateDerivedKey(byte[] encodedPassword, AlgorithmIdentifier derivationAlgorithm, int keySize)
+        throws CMSException;
+
+    protected abstract byte[] generateEncryptedBytes(AlgorithmIdentifier algorithm, byte[] derivedKey, GenericKey contentEncryptionKey)
+        throws CMSException;
+}
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