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cryptField() used to obscure extended fields in HELLO cannot use mangleKey()

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This commit is contained in:
Adam Ierymenko 2017-03-10 17:34:41 -08:00
parent 7320e26730
commit 0c00b83702
2 changed files with 4 additions and 9 deletions
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11
node/Packet.cpp
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@ -2025,14 +2025,9 @@ bool Packet::dearmor(const void *key)
void Packet::cryptField(const void *key,unsigned int start,unsigned int len)
{
unsigned char mangledKey[32];
unsigned char macKey[32];
_salsa20MangleKey((const unsigned char *)key,mangledKey);
mangledKey[0] ^= 0x7f;
mangledKey[1] ^= ((start >> 8) & 0xff);
mangledKey[2] ^= (start & 0xff); // slightly alter key for this use case as an added guard against key stream reuse
Salsa20 s20(mangledKey,256,field(ZT_PACKET_IDX_IV,8));
s20.crypt12(ZERO_KEY,macKey,sizeof(macKey)); // discard the first 32 bytes of key stream (the ones use for MAC in armor()) as a precaution
unsigned char discard[32];
Salsa20 s20(key,256,field(ZT_PACKET_IDX_IV,8));
s20.crypt12(ZERO_KEY,discard,sizeof(discard)); // discard the first 32 bytes of key stream (the ones use for MAC in armor()) as a precaution
unsigned char *const ptr = field(start,len);
s20.crypt12(ptr,ptr,len);
}