January 8, 2002
Practical Aspects of Modern
Cryptography
How to compute YX mod N
Multiplication by
Repeated Doubling
To compute X
• Y,
compute Y, 2Y, 4Y, 8Y, 16Y,…
and sum up
those values dictated by the binary representation
of X.
Example: 26Y = 2Y + 8Y + 16Y.