1 files changed, 134 insertions, 0 deletions
diff --git a/pkix/src/main/jdk1.1/org/spongycastle/cert/crmf/bc/BcFixedLengthMGF1Padder.java b/pkix/src/main/jdk1.1/org/spongycastle/cert/crmf/bc/BcFixedLengthMGF1Padder.java
new file mode 100644
index 00000000..eec071e1
--- /dev/null
+++ b/pkix/src/main/jdk1.1/org/spongycastle/cert/crmf/bc/BcFixedLengthMGF1Padder.java
@@ -0,0 +1,134 @@
+package org.spongycastle.cert.crmf.bc;
+
+import java.security.SecureRandom;
+
+import org.spongycastle.cert.crmf.EncryptedValuePadder;
+import org.spongycastle.crypto.Digest;
+import org.spongycastle.crypto.digests.SHA1Digest;
+import org.spongycastle.crypto.generators.MGF1BytesGenerator;
+import org.spongycastle.crypto.params.MGFParameters;
+
+/**
+ * An encrypted value padder that uses MGF1 as the basis of the padding.
+ */
+public class BcFixedLengthMGF1Padder
+    implements EncryptedValuePadder
+{
+    private int length;
+    private SecureRandom random;
+    private Digest dig = new SHA1Digest();
+
+    /**
+     * Create a padder to so that padded output will always be at least
+     * length bytes long.
+     *
+     * @param length fixed length for padded output.
+     */
+    public BcFixedLengthMGF1Padder(int length)
+    {
+        this(length, null);
+    }
+
+    /**
+     * Create a padder to so that padded output will always be at least
+     * length bytes long, using the passed in source of randomness to
+     * provide the random material for the padder.
+     *
+     * @param length fixed length for padded output.
+     * @param random a source of randomness.
+     */
+    public BcFixedLengthMGF1Padder(int length, SecureRandom random)
+    {
+        this.length = length;
+        this.random = random;
+    }
+
+    public byte[] getPaddedData(byte[] data)
+    {
+        byte[] bytes = new byte[length];
+        byte[] seed = new byte[dig.getDigestSize()];
+        byte[] mask = new byte[length - dig.getDigestSize()];
+
+        if (random == null)
+        {
+            random = new SecureRandom();
+        }
+
+        random.nextBytes(seed);
+
+        MGF1BytesGenerator maskGen = new MGF1BytesGenerator(dig);
+
+        maskGen.init(new MGFParameters(seed));
+
+        maskGen.generateBytes(mask, 0, mask.length);
+
+        System.arraycopy(seed, 0, bytes, 0, seed.length);
+        System.arraycopy(data, 0, bytes, seed.length, data.length);
+
+        for (int i = seed.length + data.length + 1; i != bytes.length; i++)
+        {
+            bytes[i] = (byte)(1 + nextByte(random));
+        }
+
+        for (int i = 0; i != mask.length; i++)
+        {
+            bytes[i + seed.length] ^= mask[i];
+        }
+
+        return bytes;
+    }
+
+    public byte[] getUnpaddedData(byte[] paddedData)
+    {
+        byte[] seed = new byte[dig.getDigestSize()];
+        byte[] mask = new byte[length - dig.getDigestSize()];
+
+        System.arraycopy(paddedData, 0, seed, 0, seed.length);
+
+        MGF1BytesGenerator maskGen = new MGF1BytesGenerator(dig);
+
+        maskGen.init(new MGFParameters(seed));
+
+        maskGen.generateBytes(mask, 0, mask.length);
+
+        for (int i = 0; i != mask.length; i++)
+        {
+            paddedData[i + seed.length] ^= mask[i];
+        }
+
+        int end = 0;
+
+        for (int i = paddedData.length - 1; i != seed.length; i--)
+        {
+            if (paddedData[i] == 0)
+            {
+                end = i;
+                break;
+            }
+        }
+
+        if (end == 0)
+        {
+            throw new IllegalStateException("bad padding in encoding");
+        }
+
+        byte[] data = new byte[end - seed.length];
+
+        System.arraycopy(paddedData, seed.length, data, 0, data.length);
+
+        return data;
+    }
+ 
+    private int nextByte(SecureRandom random)
+    {
+          int bits, val;
+          do
+          {
+              bits = random.nextInt() & 0x7fffffff;
+              val = bits % 255;
+          }
+          while (bits - val + 254 < 0);
+
+          return val;
+    }
+}