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using System;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Tls.Crypto.Impl
{
/// <summary>A generic TLS MAC implementation, acting as an HMAC based on some underlying Digest.</summary>
// TODO[api] sealed
public class TlsSuiteHmac
: TlsSuiteMac
{
private const long SequenceNumberPlaceholder = -1L;
protected static int GetMacSize(TlsCryptoParameters cryptoParams, TlsMac mac)
{
int macSize = mac.MacLength;
if (cryptoParams.SecurityParameters.IsTruncatedHmac)
{
macSize = System.Math.Min(macSize, 10);
}
return macSize;
}
protected readonly TlsCryptoParameters m_cryptoParams;
protected readonly TlsHmac m_mac;
protected readonly int m_digestBlockSize;
protected readonly int m_digestOverhead;
protected readonly int m_macSize;
/// <summary>Generate a new instance of a TlsMac.</summary>
/// <param name="cryptoParams">the TLS client context specific crypto parameters.</param>
/// <param name="mac">The MAC to use.</param>
public TlsSuiteHmac(TlsCryptoParameters cryptoParams, TlsHmac mac)
{
this.m_cryptoParams = cryptoParams;
this.m_mac = mac;
this.m_macSize = GetMacSize(cryptoParams, mac);
this.m_digestBlockSize = mac.InternalBlockSize;
// TODO This should check the actual algorithm, not assume based on the digest size
if (TlsImplUtilities.IsSsl(cryptoParams) && mac.MacLength == 20)
{
/*
* NOTE: For the SSL 3.0 MAC with SHA-1, the secret + input pad is not block-aligned.
*/
this.m_digestOverhead = 4;
}
else
{
this.m_digestOverhead = m_digestBlockSize / 8;
}
}
public virtual int Size
{
get { return m_macSize; }
}
public virtual byte[] CalculateMac(long seqNo, short type, byte[] msg, int msgOff, int msgLen)
{
return CalculateMac(seqNo, type, null, msg, msgOff, msgLen);
}
// TODO[api] Replace TlsSuiteMac.CalculateMac (non-span version)
public virtual byte[] CalculateMac(long seqNo, short type, byte[] connectionID, byte[] msg, int msgOff,
int msgLen)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
var connIDSpan = connectionID == null ? Span<byte>.Empty : connectionID.AsSpan();
return CalculateMac(seqNo, type, connIDSpan, msg.AsSpan(msgOff, msgLen));
#else
ProtocolVersion serverVersion = m_cryptoParams.ServerVersion;
if (serverVersion.IsSsl)
{
byte[] macHeader = new byte[11];
TlsUtilities.WriteUint64(seqNo, macHeader, 0);
TlsUtilities.WriteUint8(type, macHeader, 8);
TlsUtilities.WriteUint16(msgLen, macHeader, 9);
m_mac.Update(macHeader, 0, macHeader.Length);
}
else if (!Arrays.IsNullOrEmpty(connectionID))
{
int cidLength = connectionID.Length;
byte[] macHeader = new byte[23 + cidLength];
TlsUtilities.WriteUint64(SequenceNumberPlaceholder, macHeader, 0);
TlsUtilities.WriteUint8(ContentType.tls12_cid, macHeader, 8);
TlsUtilities.WriteUint8(cidLength, macHeader, 9);
TlsUtilities.WriteUint8(ContentType.tls12_cid, macHeader, 10);
TlsUtilities.WriteVersion(serverVersion, macHeader, 11);
TlsUtilities.WriteUint64(seqNo, macHeader, 13);
Array.Copy(connectionID, 0, macHeader, 21, cidLength);
TlsUtilities.WriteUint16(msgLen, macHeader, 21 + cidLength);
m_mac.Update(macHeader, 0, macHeader.Length);
}
else
{
byte[] macHeader = new byte[13];
TlsUtilities.WriteUint64(seqNo, macHeader, 0);
TlsUtilities.WriteUint8(type, macHeader, 8);
TlsUtilities.WriteVersion(serverVersion, macHeader, 9);
TlsUtilities.WriteUint16(msgLen, macHeader, 11);
m_mac.Update(macHeader, 0, macHeader.Length);
}
m_mac.Update(msg, msgOff, msgLen);
return Truncate(m_mac.CalculateMac());
#endif
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public virtual byte[] CalculateMac(long seqNo, short type, ReadOnlySpan<byte> message)
{
return CalculateMac(seqNo, type, ReadOnlySpan<byte>.Empty, message);
}
// TODO[api] Replace TlsSuiteMac.CalculateMac (span version)
public virtual byte[] CalculateMac(long seqNo, short type, ReadOnlySpan<byte> connectionID,
ReadOnlySpan<byte> message)
{
ProtocolVersion serverVersion = m_cryptoParams.ServerVersion;
if (serverVersion.IsSsl)
{
byte[] macHeader = new byte[11];
TlsUtilities.WriteUint64(seqNo, macHeader, 0);
TlsUtilities.WriteUint8(type, macHeader, 8);
TlsUtilities.WriteUint16(message.Length, macHeader, 9);
m_mac.Update(macHeader);
}
else if (!connectionID.IsEmpty)
{
int cidLength = connectionID.Length;
byte[] macHeader = new byte[23 + cidLength];
TlsUtilities.WriteUint64(SequenceNumberPlaceholder, macHeader, 0);
TlsUtilities.WriteUint8(ContentType.tls12_cid, macHeader, 8);
TlsUtilities.WriteUint8(cidLength, macHeader, 9);
TlsUtilities.WriteUint8(ContentType.tls12_cid, macHeader, 10);
TlsUtilities.WriteVersion(serverVersion, macHeader, 11);
TlsUtilities.WriteUint64(seqNo, macHeader, 13);
connectionID.CopyTo(macHeader.AsSpan(21));
TlsUtilities.WriteUint16(message.Length, macHeader, 21 + cidLength);
m_mac.Update(macHeader);
}
else
{
byte[] macHeader = new byte[13];
TlsUtilities.WriteUint64(seqNo, macHeader, 0);
TlsUtilities.WriteUint8(type, macHeader, 8);
TlsUtilities.WriteVersion(serverVersion, macHeader, 9);
TlsUtilities.WriteUint16(message.Length, macHeader, 11);
m_mac.Update(macHeader);
}
m_mac.Update(message);
return Truncate(m_mac.CalculateMac());
}
#endif
public virtual byte[] CalculateMacConstantTime(long seqNo, short type, byte[] msg, int msgOff, int msgLen,
int fullLength, byte[] dummyData)
{
return CalculateMacConstantTime(seqNo, type, null, msg, msgOff, msgLen, fullLength, dummyData);
}
// TODO[api] Replace TlsSuiteMac.CalculateMacConstantTime
public virtual byte[] CalculateMacConstantTime(long seqNo, short type, byte[] connectionID, byte[] msg,
int msgOff, int msgLen, int fullLength, byte[] dummyData)
{
/*
* Actual MAC only calculated on 'length' bytes...
*/
byte[] result = CalculateMac(seqNo, type, connectionID, msg, msgOff, msgLen);
/*
* ...but ensure a constant number of complete digest blocks are processed (as many as would
* be needed for 'fullLength' bytes of input).
*/
int headerLength = GetHeaderLength(connectionID);
// How many extra full blocks do we need to calculate?
int extra = GetDigestBlockCount(headerLength + fullLength) - GetDigestBlockCount(headerLength + msgLen);
while (--extra >= 0)
{
m_mac.Update(dummyData, 0, m_digestBlockSize);
}
// One more byte in case the implementation is "lazy" about processing blocks
m_mac.Update(dummyData, 0, 1);
m_mac.Reset();
return result;
}
protected virtual int GetDigestBlockCount(int inputLength)
{
// NOTE: The input pad for HMAC is always a full digest block
// NOTE: This calculation assumes a minimum of 1 pad byte
return (inputLength + m_digestOverhead) / m_digestBlockSize;
}
protected virtual int GetHeaderLength(byte[] connectionID)
{
if (TlsImplUtilities.IsSsl(m_cryptoParams))
{
return 11;
}
else if (!Arrays.IsNullOrEmpty(connectionID))
{
return 23 + connectionID.Length;
}
else
{
return 13;
}
}
protected virtual byte[] Truncate(byte[] bs)
{
if (bs.Length <= m_macSize)
return bs;
return Arrays.CopyOf(bs, m_macSize);
}
}
}
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