From e5dd692d3279a1bc79ef6b0923c2210f98ec5ed1 Mon Sep 17 00:00:00 2001 From: Arisotura Date: Tue, 25 Aug 2020 00:17:22 +0200 Subject: AES: fix bug where CCM-encrypt MAC could be obliterated, by attempting to write it while the output FIFO was full --- src/DSi_AES.cpp | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) (limited to 'src/DSi_AES.cpp') diff --git a/src/DSi_AES.cpp b/src/DSi_AES.cpp index dfa67bd..8f5c3f3 100644 --- a/src/DSi_AES.cpp +++ b/src/DSi_AES.cpp @@ -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); -- cgit v1.2.3