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implement session and mac key if shared key is shorter than 64 bytes

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orignal 2014-04-15 11:53:24 -04:00
parent 002b023b29
commit 25e16f1693
1 changed files with 25 additions and 8 deletions
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33
SSU.cpp
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@ -1,7 +1,7 @@
#include <string.h> #include <string.h>
#include <boost/bind.hpp> #include <boost/bind.hpp>
#include <cryptopp/dh.h> #include <cryptopp/dh.h>
#include <cryptopp/secblock.h> #include <cryptopp/sha.h>
#include "CryptoConst.h" #include "CryptoConst.h"
#include "Log.h" #include "Log.h"
#include "Timestamp.h" #include "Timestamp.h"
@ -38,23 +38,40 @@ namespace ssu
void SSUSession::CreateAESandMacKey (const uint8_t * pubKey, uint8_t * aesKey, uint8_t * macKey) void SSUSession::CreateAESandMacKey (const uint8_t * pubKey, uint8_t * aesKey, uint8_t * macKey)
{ {
CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg); CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
CryptoPP::SecByteBlock secretKey(dh.AgreedValueLength()); uint8_t sharedKey[64];
if (!dh.Agree (secretKey, m_DHKeysPair->privateKey, pubKey)) if (!dh.Agree (sharedKey, m_DHKeysPair->privateKey, pubKey))
{ {
LogPrint ("Couldn't create shared key"); LogPrint ("Couldn't create shared key");
return; return;
}; };
if (secretKey[0] & 0x80) if (sharedKey[0] & 0x80)
{ {
aesKey[0] = 0; aesKey[0] = 0;
memcpy (aesKey + 1, secretKey, 31); memcpy (aesKey + 1, sharedKey, 31);
memcpy (macKey, secretKey + 31, 32); memcpy (macKey, sharedKey + 31, 32);
}
else if (sharedKey[0])
{
memcpy (aesKey, sharedKey, 32);
memcpy (macKey, sharedKey + 32, 32);
} }
else else
{ {
memcpy (aesKey, secretKey, 32); // find first non-zero byte
memcpy (macKey, secretKey + 32, 32); uint8_t * nonZero = sharedKey + 1;
while (!*nonZero)
{
nonZero++;
if (nonZero - sharedKey > 32)
{
LogPrint ("First 32 bytes of shared key is all zeros. Ignored");
return;
}
}
memcpy (aesKey, nonZero, 32);
CryptoPP::SHA256().CalculateDigest(macKey, nonZero, 64 - (nonZero - sharedKey));
} }
m_IsSessionKey = true; m_IsSessionKey = true;
} }