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AES: fix bug where CCM-encrypt MAC could be obliterated, by attempting to write it while the output FIFO was full

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This commit is contained in:
Arisotura 2020-08-25 00:17:22 +02:00
parent 2ee6145fd7
commit e5dd692d32
1 changed files with 20 additions and 7 deletions
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27
src/DSi_AES.cpp
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@ -52,6 +52,10 @@ u8 KeyY[4][16];
u8 CurKey[16];
u8 CurMAC[16];
// output MAC for CCM encrypt
u8 OutputMAC[16];
bool OutputMACDue;
AES_ctx Ctx;
@ -129,6 +133,9 @@ void Reset()
memset(CurKey, 0, sizeof(CurKey));
memset(CurMAC, 0, sizeof(CurMAC));
memset(OutputMAC, 0, sizeof(OutputMAC));
OutputMACDue = false;
// initialize keys
// slot 0: modcrypt
@ -272,6 +279,8 @@ void WriteCnt(u32 val)
// transfer start (checkme)
RemBlocks = BlkCnt >> 16;
OutputMACDue = false;
if (AESMode == 0 && (!(val & (1<<20)))) printf("AES: CCM-DECRYPT MAC FROM WRFIFO, TODO\n");
if (RemBlocks > 0)
@ -347,6 +356,15 @@ u32 ReadOutputFIFO()
DSi::CheckNDMAs(1, 0x2B);
else
DSi::StopNDMAs(1, 0x2B);
if (OutputMACDue && OutputFIFO->Level() <= 12)
{
OutputFIFO->Write(*(u32*)&OutputMAC[0]);
OutputFIFO->Write(*(u32*)&OutputMAC[4]);
OutputFIFO->Write(*(u32*)&OutputMAC[8]);
OutputFIFO->Write(*(u32*)&OutputMAC[12]);
OutputMACDue = false;
}
}
return ret;
@ -429,13 +447,8 @@ void Update()
Ctx.Iv[15] = 0x00;
AES_CTR_xcrypt_buffer(&Ctx, CurMAC, 16);
u8 finalmac[16];
Swap16(finalmac, CurMAC);
OutputFIFO->Write(*(u32*)&finalmac[0]);
OutputFIFO->Write(*(u32*)&finalmac[4]);
OutputFIFO->Write(*(u32*)&finalmac[8]);
OutputFIFO->Write(*(u32*)&finalmac[12]);
Swap16(OutputMAC, CurMAC);
OutputMACDue = true;
// CHECKME
Cnt &= ~(1<<21);