rsa bugs

darcs-hash:20040604101337-24bed-551df0d1e6f3709acbec210d6f5716f0f76f0ecb.gz

diff --git a/src/org/ibex/crypto/RSA.java b/src/org/ibex/crypto/RSA.java
index 7156cce..546d323 100644 (file)
--- a/src/org/ibex/crypto/RSA.java
+++ b/src/org/ibex/crypto/RSA.java
@@ -20,15 +20,17 @@ public class RSA {
     public int getInputBlockSize() { return (pq.bitLength()+7) / 8 - (reverse ? 0 : 1); }
     public int getOutputBlockSize() { return (pq.bitLength()+7) / 8 - (reverse ? 1 : 0); }
     
+    // FEATURE: Check that in.length is within the expected range
     public byte[] process(byte[] in) {
         // output block is the same size as the modulus (rounded up)
         int outSize = getOutputBlockSize();
         BigInteger t = new BigInteger(1,in);
         BigInteger c = t.modPow(e,pq);
         byte[] cbytes = c.toByteArray();
-        if(cbytes.length > outSize || (reverse && cbytes[0] == 0)) {
+        if(cbytes.length > outSize + 1) throw new RuntimeException("should never happen");
+        if(reverse ? cbytes[0] == 0 : cbytes.length > outSize) {
             if(cbytes[0] != 0) throw new RuntimeException("should never happen");
-            byte[] buf = new byte[outSize];
+            byte[] buf = new byte[cbytes.length-1];
             System.arraycopy(cbytes,1,buf,0,outSize);
             return buf;
         } else if(!reverse && cbytes.length < outSize) {