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feat: add more shifting capabilities for gfmul

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0xalivecow 2024-10-29 14:50:55 +01:00
parent f4c49a9137
commit ccf0b03ec0
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2 changed files with 57 additions and 17 deletions
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54
src/utils/math.rs
View file

@ -15,14 +15,28 @@ pub fn xor_bytes(vec1: &Vec<u8>, mut vec2: Vec<u8>) -> Result<Vec<u8>> {
pub struct ByteArray(pub Vec<u8>);
impl ByteArray {
pub fn left_shift(&mut self) -> u8 {
pub fn left_shift(&mut self, semantic: &str) -> Result<u8> {
match semantic {
"xex" => {
let mut carry = 0u8;
for byte in self.0.iter_mut() {
let new_carry = *byte >> 7;
*byte = (*byte << 1) | carry;
carry = new_carry;
}
carry
Ok(carry)
}
"gcm" => {
let mut carry = 0u8;
for byte in self.0.iter_mut() {
let new_carry = *byte & 1;
*byte = (*byte >> 1) | (carry << 7);
carry = new_carry;
}
Ok(carry)
}
_ => Err(anyhow!("Failure in lsh. No compatible action found")),
}
}
pub fn left_shift_reduce(&mut self, semantic: &str) {
@ -97,7 +111,7 @@ mod tests {
fn test_byte_array_shift1() {
let mut byte_array: ByteArray = ByteArray(vec![0x00, 0x01]);
let shifted_array: ByteArray = ByteArray(vec![0x00, 0x02]);
byte_array.left_shift();
byte_array.left_shift("xex");
assert_eq!(byte_array.0, shifted_array.0);
}
@ -106,7 +120,7 @@ mod tests {
fn test_byte_array_shift2() {
let mut byte_array: ByteArray = ByteArray(vec![0xFF, 0x00]);
let shifted_array: ByteArray = ByteArray(vec![0xFE, 0x01]);
byte_array.left_shift();
byte_array.left_shift("xex");
assert_eq!(
byte_array.0, shifted_array.0,
@ -115,6 +129,32 @@ mod tests {
);
}
#[test]
fn test_byte_array_shift1_gcm() {
let mut byte_array: ByteArray = ByteArray(vec![0xFF, 0x00]);
let shifted_array: ByteArray = ByteArray(vec![0x7F, 0x80]);
byte_array.left_shift("gcm");
assert_eq!(
byte_array.0, shifted_array.0,
"Failure: Shifted array was: {:02X?}",
byte_array.0
);
}
#[test]
fn test_byte_array_shift1_right_gcm() {
let mut byte_array: ByteArray = ByteArray(vec![0xFF, 0x00]);
let shifted_array: ByteArray = ByteArray(vec![0xFE, 0x00]);
byte_array.right_shift("gcm");
assert_eq!(
byte_array.0, shifted_array.0,
"Failure: Shifted array was: {:02X?}",
byte_array.0
);
}
#[test]
fn test_byte_array_shift_right() {
let mut byte_array: ByteArray = ByteArray(vec![0x02]);
@ -130,13 +170,13 @@ mod tests {
#[test]
fn test_lsb_one() {
let mut byte_array: ByteArray = ByteArray(vec![0x00, 0xFF]);
let byte_array: ByteArray = ByteArray(vec![0x00, 0xFF]);
assert!(!byte_array.LSB_is_one());
let mut byte_array2: ByteArray = ByteArray(vec![0x02, 0xFF]);
let byte_array2: ByteArray = ByteArray(vec![0x02, 0xFF]);
assert!(!byte_array2.LSB_is_one());
let mut byte_array3: ByteArray = ByteArray(vec![0xFF, 0x00]);
let byte_array3: ByteArray = ByteArray(vec![0xFF, 0x00]);
assert!(byte_array3.LSB_is_one());
}

10
src/utils/poly.rs
View file

@ -19,21 +19,21 @@ pub fn gfmul(poly_a: Vec<u8>, poly_b: Vec<u8>, semantic: &str) -> Result<Vec<u8>
if poly2.LSB_is_one() {
result.xor_byte_arrays(&poly1);
poly2.right_shift(semantic);
poly2.right_shift(semantic)?;
} else {
poly2.right_shift(semantic);
poly2.right_shift(semantic)?;
}
while !poly2.is_empty() {
if poly2.LSB_is_one() {
poly1.left_shift();
poly1.left_shift(semantic)?;
poly1.xor_byte_arrays(&red_poly_bytes);
result.xor_byte_arrays(&poly1);
} else {
poly1.left_shift();
poly1.left_shift(semantic)?;
poly1.xor_byte_arrays(&red_poly_bytes);
}
poly2.right_shift(semantic);
poly2.right_shift(semantic)?;
}
result.0.remove(16);