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using System;
using System.Collections;
using System.IO;
using Org.BouncyCastle.Tls.Crypto;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Tls
{
/// <summary>Buffers input until the hash algorithm is determined.</summary>
internal sealed class DeferredHash
: TlsHandshakeHash
{
private const int BufferingHashLimit = 4;
private readonly TlsContext m_context;
private DigestInputBuffer m_buf;
private IDictionary m_hashes;
private bool m_forceBuffering;
private bool m_sealed;
internal DeferredHash(TlsContext context)
{
this.m_context = context;
this.m_buf = new DigestInputBuffer();
this.m_hashes = Platform.CreateHashtable();
this.m_forceBuffering = false;
this.m_sealed = false;
}
/// <exception cref="IOException"/>
public void CopyBufferTo(Stream output)
{
if (m_buf == null)
{
// If you see this, you need to call ForceBuffering() before SealHashAlgorithms()
throw new InvalidOperationException("Not buffering");
}
m_buf.CopyTo(output);
}
public void ForceBuffering()
{
if (m_sealed)
throw new InvalidOperationException("Too late to force buffering");
this.m_forceBuffering = true;
}
public void NotifyPrfDetermined()
{
SecurityParameters securityParameters = m_context.SecurityParameters;
switch (securityParameters.PrfAlgorithm)
{
case PrfAlgorithm.ssl_prf_legacy:
case PrfAlgorithm.tls_prf_legacy:
{
CheckTrackingHash(CryptoHashAlgorithm.md5);
CheckTrackingHash(CryptoHashAlgorithm.sha1);
break;
}
default:
{
CheckTrackingHash(securityParameters.PrfCryptoHashAlgorithm);
break;
}
}
}
public void TrackHashAlgorithm(int cryptoHashAlgorithm)
{
if (m_sealed)
throw new InvalidOperationException("Too late to track more hash algorithms");
CheckTrackingHash(cryptoHashAlgorithm);
}
public void SealHashAlgorithms()
{
if (m_sealed)
throw new InvalidOperationException("Already sealed");
this.m_sealed = true;
CheckStopBuffering();
}
public void StopTracking()
{
SecurityParameters securityParameters = m_context.SecurityParameters;
IDictionary newHashes = Platform.CreateHashtable();
switch (securityParameters.PrfAlgorithm)
{
case PrfAlgorithm.ssl_prf_legacy:
case PrfAlgorithm.tls_prf_legacy:
{
CloneHash(newHashes, HashAlgorithm.md5);
CloneHash(newHashes, HashAlgorithm.sha1);
break;
}
default:
{
CloneHash(newHashes, securityParameters.PrfCryptoHashAlgorithm);
break;
}
}
this.m_buf = null;
this.m_hashes = newHashes;
this.m_forceBuffering = false;
this.m_sealed = true;
}
public TlsHash ForkPrfHash()
{
CheckStopBuffering();
SecurityParameters securityParameters = m_context.SecurityParameters;
TlsHash prfHash;
switch (securityParameters.PrfAlgorithm)
{
case PrfAlgorithm.ssl_prf_legacy:
case PrfAlgorithm.tls_prf_legacy:
{
prfHash = new CombinedHash(m_context, CloneHash(HashAlgorithm.md5), CloneHash(HashAlgorithm.sha1));
break;
}
default:
{
prfHash = CloneHash(securityParameters.PrfCryptoHashAlgorithm);
break;
}
}
if (m_buf != null)
{
m_buf.UpdateDigest(prfHash);
}
return prfHash;
}
public byte[] GetFinalHash(int cryptoHashAlgorithm)
{
TlsHash d = (TlsHash)m_hashes[cryptoHashAlgorithm];
if (d == null)
throw new InvalidOperationException("CryptoHashAlgorithm." + cryptoHashAlgorithm
+ " is not being tracked");
CheckStopBuffering();
d = d.CloneHash();
if (m_buf != null)
{
m_buf.UpdateDigest(d);
}
return d.CalculateHash();
}
public void Update(byte[] input, int inOff, int len)
{
if (m_buf != null)
{
m_buf.Write(input, inOff, len);
return;
}
foreach (TlsHash hash in m_hashes.Values)
{
hash.Update(input, inOff, len);
}
}
public byte[] CalculateHash()
{
throw new InvalidOperationException("Use 'ForkPrfHash' to get a definite hash");
}
public TlsHash CloneHash()
{
throw new InvalidOperationException("attempt to clone a DeferredHash");
}
public void Reset()
{
if (m_buf != null)
{
m_buf.SetLength(0);
return;
}
foreach (TlsHash hash in m_hashes.Values)
{
hash.Reset();
}
}
private void CheckStopBuffering()
{
if (!m_forceBuffering && m_sealed && m_buf != null && m_hashes.Count <= BufferingHashLimit)
{
foreach (TlsHash hash in m_hashes.Values)
{
m_buf.UpdateDigest(hash);
}
this.m_buf = null;
}
}
private void CheckTrackingHash(int cryptoHashAlgorithm)
{
if (!m_hashes.Contains(cryptoHashAlgorithm))
{
TlsHash hash = m_context.Crypto.CreateHash(cryptoHashAlgorithm);
m_hashes[cryptoHashAlgorithm] = hash;
}
}
private TlsHash CloneHash(int cryptoHashAlgorithm)
{
return ((TlsHash)m_hashes[cryptoHashAlgorithm]).CloneHash();
}
private void CloneHash(IDictionary newHashes, int cryptoHashAlgorithm)
{
TlsHash hash = CloneHash(cryptoHashAlgorithm);
if (m_buf != null)
{
m_buf.UpdateDigest(hash);
}
newHashes[cryptoHashAlgorithm] = hash;
}
}
}
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