From c8354a4635bc66c4878eca13b0c0ebc9da266839 Mon Sep 17 00:00:00 2001
From: Peter Dettman <peter.dettman@bouncycastle.org>
Date: Fri, 9 Jun 2017 17:38:17 +0700
Subject: Add validation to RSA public key constructor

---
 crypto/src/crypto/parameters/RsaKeyParameters.cs | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

(limited to 'crypto/src')

diff --git a/crypto/src/crypto/parameters/RsaKeyParameters.cs b/crypto/src/crypto/parameters/RsaKeyParameters.cs
index 72c0d806f..5480f0561 100644
--- a/crypto/src/crypto/parameters/RsaKeyParameters.cs
+++ b/crypto/src/crypto/parameters/RsaKeyParameters.cs
@@ -8,6 +8,26 @@ namespace Org.BouncyCastle.Crypto.Parameters
 	public class RsaKeyParameters
 		: AsymmetricKeyParameter
     {
+        // the value is the product of the 132 smallest primes from 3 to 751
+        private static BigInteger SmallPrimesProduct = new BigInteger( 
+            "8138E8A0FCF3A4E84A771D40FD305D7F4AA59306D7251DE54D98AF8FE95729A1" +
+            "F73D893FA424CD2EDC8636A6C3285E022B0E3866A565AE8108EED8591CD4FE8D" +
+            "2CE86165A978D719EBF647F362D33FCA29CD179FB42401CBAF3DF0C614056F9C" +
+            "8F3CFD51E474AFB6BC6974F78DB8ABA8E9E517FDED658591AB7502BD41849462F",
+            16);
+
+        private static BigInteger Validate(BigInteger modulus)
+        {
+            if ((modulus.IntValue & 1) == 0)
+                throw new ArgumentException("RSA modulus is even", "modulus");
+            if (!modulus.Gcd(SmallPrimesProduct).Equals(BigInteger.One))
+                throw new ArgumentException("RSA modulus has a small prime factor");
+
+            // TODO: add additional primePower/Composite test - expensive!!
+
+            return modulus;
+        }
+
         private readonly BigInteger modulus;
         private readonly BigInteger exponent;
 
@@ -25,8 +45,10 @@ namespace Org.BouncyCastle.Crypto.Parameters
 				throw new ArgumentException("Not a valid RSA modulus", "modulus");
 			if (exponent.SignValue <= 0)
 				throw new ArgumentException("Not a valid RSA exponent", "exponent");
+            if (!isPrivate && (exponent.IntValue & 1) == 0)
+                throw new ArgumentException("RSA publicExponent is even", "exponent");
 
-			this.modulus = modulus;
+            this.modulus = Validate(modulus);
 			this.exponent = exponent;
         }
 
-- 
cgit 1.5.1