From 63d9caf1c22b51a44ac45104b6b29528671941eb Mon Sep 17 00:00:00 2001 From: Barry Mead Date: Tue, 16 Feb 2010 20:36:49 -0700 Subject: better comments about safe bit --- rsa/fastrsa.py | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/rsa/fastrsa.py b/rsa/fastrsa.py index 7a1156c..529da0b 100644 --- a/rsa/fastrsa.py +++ b/rsa/fastrsa.py @@ -409,7 +409,7 @@ def encrypt_int(message, key): raise OverflowError("The message is too long") #Note: Bit exponents start at zero (bit counts start at 1) this is correct - safebit = int(math.floor(math.log(key['n'],2))) - 1 #compute safe bit (MSB - 1) + safebit = int(math.floor(math.log(key['n'],2))) - 1 #safe bit is (MSB - 1) message += (1 << safebit) #add safebit to ensure folding return fast_exponentiation(message, key['e'], key['n']) @@ -426,7 +426,7 @@ def verify_int(cyphertext, key): message = fast_exponentiation(cyphertext, key['e'], key['n']) #Note: Bit exponents start at zero (bit counts start at 1) this is correct - safebit = int(math.floor(math.log(key['n'],2))) - 1 #safe bit (MSB - 1) + safebit = int(math.floor(math.log(key['n'],2))) - 1 #safe bit is (MSB - 1) message -= (1 << safebit) #remove safe bit before decode return message @@ -444,7 +444,7 @@ def decrypt_int(cyphertext, key): h = (key['qi'] * dif) % key['p'] message = m2 + (h * key['q']) - safebit = int(math.floor(math.log(n,2))) - 1 #compute safe bit (MSB - 1) + safebit = int(math.floor(math.log(n,2))) - 1 #safe bit is (MSB - 1) message -= (1 << safebit) #remove safebit before decode return message @@ -464,7 +464,7 @@ def sign_int(message, key): if message < 0 or message > n: raise OverflowError("The message is too long") - safebit = int(math.floor(math.log(n,2))) - 1 #compute safe bit (MSB - 1) + safebit = int(math.floor(math.log(n,2))) - 1 #safe bit is (MSB - 1) message += (1 << safebit) #add safebit before encrypt #Encrypt in 2 parts, using faster Chinese Remainder Theorem method -- cgit v1.2.1