diff options
Diffstat (limited to 'crypto/bn/old/info')
| -rw-r--r-- | crypto/bn/old/info | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/crypto/bn/old/info b/crypto/bn/old/info new file mode 100644 index 0000000000..5ac99c3b23 --- /dev/null +++ b/crypto/bn/old/info @@ -0,0 +1,22 @@ +Given A1A0 * B1B0 == S3S2S1S0 + +S0= low(A0*B0) +S1= low( (A1-A0)*(B0-B1)) +low( A1*B1) +high(A0*B0) +S2= high((A1-A0)*(B0-B1)) +high(A1*B1) +low( A1*B1) +S3= high(A1*B1); + +Assume we know S1 and S0, and can calulate A1*B1 and high((A1-A0)*(B0-B1)) + +k0= S0 == low(A0*B0) +k1= S1 +k2= low( A1*B1) +k3= high(A1*B1) +k4= high((A1-A0)*(B0-B1)) + +k1= low((A1-A0)*(B0-B1)) +k2 +high(A0*B0) +S2= k4 +k3 +k2 +S3= k3 + +S1-k2= low((A1-A0)*(B0-B1)) +high(A0*B0) + +We potentially have a carry or a borrow from S1 |