I can make Meow pass the LongNeighbors test by doubling the number of AES rounds on each pass. The original Meow algo: while(Len >= 64) { S0 =

I can make Meow pass the LongNeighbors test by doubling the number of AES rounds on each pass. The original Meow algo: while(Len >= 64) { S0 = Meow128_AESDEC_Mem(S0, Source); S1 = Meow128_AESDEC_Mem(S1, Source + 16); S2 = Meow128_AESDEC_Mem(S2, Source + 32); S3 = Meow128_AESDEC_Mem(S3, Source + 48); Len -= 64; Source += 64; } The modified algo: while(Len >= 64) { S0 = Meow128_AESDEC_Mem(S0, Source); S0 = Meow128_AESDEC_Mem(S0, Source); S1 = Meow128_AESDEC_Mem(S1, Source + 16); S1 = Meow128_AESDEC_Mem(S1, Source + 16); S2 = Meow128_AESDEC_Mem(S2, Source + 32); S2 = Meow128_AESDEC_Mem(S2, Source + 32); S3 = Meow128_AESDEC_Mem(S3, Source + 48); S3 = Meow128_AESDEC_Mem(S3, Source + 48); Len -= 64; Source += 64; } (also changed the partial rounds, but this is not shown here) This doesn't change it's performance that much, maybe 1 or 2 extra CPU cycles. My i9 CPU must be able to run these extra rounds in parallel... I do have hyperthreading disabled, if that matters. Update: Ah, it does cause the bulk speed test to be 50% of the original (48MiB vs 24Mib). The small key test only adds 1/2/3/4 extra AES instructions since they are manipulating 16 bytes at a time. It looks like this is only taking a cycle.