diff options
Diffstat (limited to 'crypto/src/security/SecureRandom.cs')
| -rw-r--r-- | crypto/src/security/SecureRandom.cs | 153 |
1 files changed, 89 insertions, 64 deletions
diff --git a/crypto/src/security/SecureRandom.cs b/crypto/src/security/SecureRandom.cs index 160628d4b..f46427a5c 100644 --- a/crypto/src/security/SecureRandom.cs +++ b/crypto/src/security/SecureRandom.cs @@ -1,4 +1,5 @@ using System; +using System.Threading; using Org.BouncyCastle.Crypto; using Org.BouncyCastle.Crypto.Digests; @@ -10,78 +11,113 @@ namespace Org.BouncyCastle.Security public class SecureRandom : Random { - // Note: all objects of this class should be deriving their random data from - // a single generator appropriate to the digest being used. - private static readonly IRandomGenerator sha1Generator = new DigestRandomGenerator(new Sha1Digest()); - private static readonly IRandomGenerator sha256Generator = new DigestRandomGenerator(new Sha256Digest()); + private static long counter = Times.NanoTime(); + private static long NextCounterValue() + { + return Interlocked.Increment(ref counter); + } + +#if NETCF_1_0 private static readonly SecureRandom[] master = { null }; private static SecureRandom Master { get { - if (master[0] == null) + lock (master) { - SecureRandom sr = master[0] = new SecureRandom(sha256Generator); - - // Even though Ticks has at most 8 or 14 bits of entropy, there's no harm in adding it. - sr.SetSeed(DateTime.Now.Ticks); - // In addition to Ticks and ThreadedSeedGenerator, also seed from CryptoApiRandomGenerator - CryptoApiRandomGenerator systemRNG = new CryptoApiRandomGenerator(); - byte[] systemSeed = new byte[32]; - systemRNG.NextBytes(systemSeed); - sr.SetSeed(systemSeed); - Array.Clear(systemSeed,0,systemSeed.Length); - // 32 will be enough when ThreadedSeedGenerator is fixed. Until then, ThreadedSeedGenerator returns low - // entropy, and this is not sufficient to be secure. http://www.bouncycastle.org/csharpdevmailarchive/msg00814.html - sr.SetSeed(new ThreadedSeedGenerator().GenerateSeed(32, true)); - } + if (master[0] == null) + { + SecureRandom sr = master[0] = GetInstance("SHA256PRNG", false); + + // Even though Ticks has at most 8 or 14 bits of entropy, there's no harm in adding it. + sr.SetSeed(DateTime.Now.Ticks); + + // 32 will be enough when ThreadedSeedGenerator is fixed. Until then, ThreadedSeedGenerator returns low + // entropy, and this is not sufficient to be secure. http://www.bouncycastle.org/csharpdevmailarchive/msg00814.html + sr.SetSeed(new ThreadedSeedGenerator().GenerateSeed(32, true)); + } - return master[0]; + return master[0]; + } } } - - public static SecureRandom GetInstance( - string algorithm) +#else + private static readonly SecureRandom master = new SecureRandom(new CryptoApiRandomGenerator()); + private static SecureRandom Master { - // TODO Support all digests more generally, by stripping PRNG and calling DigestUtilities? - string drgName = Platform.ToUpperInvariant(algorithm); + get { return master; } + } +#endif - if (drgName == "SHA1PRNG") + private static DigestRandomGenerator CreatePrng(string digestName, bool autoSeed) + { + IDigest digest = DigestUtilities.GetDigest(digestName); + if (digest == null) + return null; + DigestRandomGenerator prng = new DigestRandomGenerator(digest); + if (autoSeed) { - SecureRandom newPrng = new SecureRandom(sha1Generator); - newPrng.SetSeed(GetSeed(20)); - return newPrng; + prng.AddSeedMaterial(NextCounterValue()); + prng.AddSeedMaterial(GetSeed(digest.GetDigestSize())); } - else if (drgName == "SHA256PRNG") + return prng; + } + + /// <summary> + /// Create and auto-seed an instance based on the given algorithm. + /// </summary> + /// <remarks>Equivalent to GetInstance(algorithm, true)</remarks> + /// <param name="algorithm">e.g. "SHA256PRNG"</param> + public static SecureRandom GetInstance(string algorithm) + { + return GetInstance(algorithm, true); + } + + /// <summary> + /// Create an instance based on the given algorithm, with optional auto-seeding + /// </summary> + /// <param name="algorithm">e.g. "SHA256PRNG"</param> + /// <param name="autoSeed">If true, the instance will be auto-seeded.</param> + public static SecureRandom GetInstance(string algorithm, bool autoSeed) + { + string upper = Platform.ToUpperInvariant(algorithm); + if (upper.EndsWith("PRNG")) { - SecureRandom newPrng = new SecureRandom(sha256Generator); - newPrng.SetSeed(GetSeed(32)); - return newPrng; + string digestName = upper.Substring(0, upper.Length - "PRNG".Length); + DigestRandomGenerator prng = CreatePrng(digestName, autoSeed); + if (prng != null) + { + return new SecureRandom(prng); + } } throw new ArgumentException("Unrecognised PRNG algorithm: " + algorithm, "algorithm"); } - public static byte[] GetSeed( - int length) + public static byte[] GetSeed(int length) { +#if NETCF_1_0 + lock (master) +#endif return Master.GenerateSeed(length); } - protected IRandomGenerator generator; + protected readonly IRandomGenerator generator; public SecureRandom() - : this(sha1Generator) + : this(CreatePrng("SHA256", true)) { - SetSeed(GetSeed(20)); // 20 bytes because this is sha1Generator } - public SecureRandom( - byte[] inSeed) - : this(sha1Generator) + /// <remarks> + /// To replicate existing predictable output, replace with GetInstance("SHA1PRNG", false), followed by SetSeed(seed) + /// </remarks> + [Obsolete("Use GetInstance/SetSeed instead")] + public SecureRandom(byte[] seed) + : this(CreatePrng("SHA1", false)) { - SetSeed(inSeed); + SetSeed(seed); } /// <summary>Use the specified instance of IRandomGenerator as random source.</summary> @@ -92,15 +128,13 @@ namespace Org.BouncyCastle.Security /// implementation. /// </remarks> /// <param name="generator">The source to generate all random bytes from.</param> - public SecureRandom( - IRandomGenerator generator) + public SecureRandom(IRandomGenerator generator) : base(0) { this.generator = generator; } - public virtual byte[] GenerateSeed( - int length) + public virtual byte[] GenerateSeed(int length) { SetSeed(DateTime.Now.Ticks); @@ -109,14 +143,12 @@ namespace Org.BouncyCastle.Security return rv; } - public virtual void SetSeed( - byte[] inSeed) + public virtual void SetSeed(byte[] seed) { - generator.AddSeedMaterial(inSeed); + generator.AddSeedMaterial(seed); } - public virtual void SetSeed( - long seed) + public virtual void SetSeed(long seed) { generator.AddSeedMaterial(seed); } @@ -132,8 +164,7 @@ namespace Org.BouncyCastle.Security } } - public override int Next( - int maxValue) + public override int Next(int maxValue) { if (maxValue < 2) { @@ -162,9 +193,7 @@ namespace Org.BouncyCastle.Security return result; } - public override int Next( - int minValue, - int maxValue) + public override int Next(int minValue, int maxValue) { if (maxValue <= minValue) { @@ -187,18 +216,14 @@ namespace Org.BouncyCastle.Security } } - public override void NextBytes( - byte[] buffer) + public override void NextBytes(byte[] buf) { - generator.NextBytes(buffer); + generator.NextBytes(buf); } - public virtual void NextBytes( - byte[] buffer, - int start, - int length) + public virtual void NextBytes(byte[] buf, int off, int len) { - generator.NextBytes(buffer, start, length); + generator.NextBytes(buf, off, len); } private static readonly double DoubleScale = System.Math.Pow(2.0, 64.0); |