\x03\x03\x03
.paduster
specifying the -plaintext parameter:padbuster
will automatically try to find when the padding error occurs, but you can also indicating the error message it using the -error parameter.C15 = D(E15) ^ E7 = I15 ^ E7
C14 = I14 ^ E6
C13 = I13 ^ E5
C12 = I12 ^ E4
E7
until C15
is 0x01
, which will also be a correct padding. So, in this case: \x01 = I15 ^ E'7
I15 = 0x01 ^ E'7
C15 = E7 ^ I15 = E7 ^ \x01 ^ E'7
\x02\x02
.E''15
whose value is 0x02: E''7 = \x02 ^ I15
so it's just needed to find the E'14
that generates a C14
equals to 0x02
.
Then, do the same steps to decrypt C14: C14 = E6 ^ I14 = E6 ^ \x02 ^ E''6