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optimized sha256_bytearray #8322

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169 changes: 144 additions & 25 deletions corelib/src/sha256.cairo
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
//! 0x7d17648, 0x26381969]);
//! ```
use starknet::SyscallResultTrait;

use crate::bytes_31::one_shift_left_bytes_u128;
/// A handle to the state of a SHA-256 hash.
pub(crate) extern type Sha256StateHandle;

Expand Down Expand Up @@ -81,30 +81,50 @@ pub fn compute_sha256_u32_array(
//! 0x7d17648, 0x26381969]);
/// ```
pub fn compute_sha256_byte_array(arr: @ByteArray) -> [u32; 8] {
let mut word_arr = array![];
let len = arr.len();
let rem = len % 4;
let mut index = 0;
let rounded_len = len - rem;
while index != rounded_len {
let word = arr.at(index + 3).unwrap().into()
+ arr.at(index + 2).unwrap().into() * 0x100
+ arr.at(index + 1).unwrap().into() * 0x10000
+ arr.at(index).unwrap().into() * 0x1000000;
word_arr.append(word);
index = index + 4;
}

let last = match rem {
0 => 0,
1 => arr.at(len - 1).unwrap().into(),
2 => arr.at(len - 1).unwrap().into() + arr.at(len - 2).unwrap().into() * 0x100,
_ => arr.at(len - 1).unwrap().into()
+ arr.at(len - 2).unwrap().into() * 0x100
+ arr.at(len - 3).unwrap().into() * 0x10000,
};

compute_sha256_u32_array(word_arr, last, rem.into())
let mut span = Span { snapshot: arr.data };

let mut words_arr = array![];
let mut last_word = 0;
let mut last_word_len = 0;
while let Option::Some(byte_31) = span.pop_front() {
let u256 { mut low, mut high } = (*byte_31).into();
let mut shift = BYTES_IN_U128 - 1 - 4 + last_word_len;
append_u128_to_words_array(ref words_arr, high, ref last_word, ref last_word_len, shift);
let mut shift = BYTES_IN_U128 - 4 + last_word_len;
append_u128_to_words_array(ref words_arr, low, ref last_word, ref last_word_len, shift);
}
let u256 { mut low, mut high } = (*arr.pending_word).into();
if *arr.pending_word_len > BYTES_IN_U128 {
let mut shift = *arr.pending_word_len - BYTES_IN_U128 + last_word_len;
if shift >= 4 {
shift = shift - 4;
append_u128_to_words_array_partial(
ref words_arr, high, ref last_word, ref last_word_len, shift,
);
} else {
last_word = (last_word.into() * one_shift_left_bytes_u128(last_word_len) + high)
.try_into()
.unwrap();
last_word_len = last_word_len + *arr.pending_word_len - BYTES_IN_U128;
}
let mut shift = BYTES_IN_U128 - 4 + last_word_len;
append_u128_to_words_array(ref words_arr, low, ref last_word, ref last_word_len, shift);
} else {
let mut shift = *arr.pending_word_len + last_word_len;
if shift >= 4 {
shift = shift - 4;
append_u128_to_words_array_partial(
ref words_arr, low, ref last_word, ref last_word_len, shift,
);
} else {
last_word = (last_word.into() * one_shift_left_bytes_u128(*arr.pending_word_len) + low)
.try_into()
.unwrap();
last_word_len = last_word_len + *arr.pending_word_len;
}
}

return compute_sha256_u32_array(words_arr, last_word, last_word_len);
}

/// Adds padding to the input array according to the SHA-256 specification.
Expand Down Expand Up @@ -208,3 +228,102 @@ fn append_zeros(ref arr: Array<u32>, count: felt252) {
}
arr.append(0);
}

const BYTES_IN_U128: usize = 16;

/// Appends `val` to the words array.
fn append_u128_to_words_array_partial(
ref words_arr: Array<u32>,
val: u128,
ref last_word: u32,
ref last_word_len: u32,
mut shift: u32,
) {
words_arr
.append(
(last_word.into() * one_shift_left_bytes_u128(4 - last_word_len)
+ val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
if shift < 4 {
last_word = (val % one_shift_left_bytes_u128(shift)).try_into().unwrap();
last_word_len = shift;
return;
}
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
if shift < 4 {
last_word = (val % one_shift_left_bytes_u128(shift)).try_into().unwrap();
last_word_len = shift;
return;
}
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
if shift < 4 {
last_word = (val % one_shift_left_bytes_u128(shift)).try_into().unwrap();
last_word_len = shift;
return;
}
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
last_word = (val % one_shift_left_bytes_u128(shift)).try_into().unwrap();
last_word_len = shift;
}

/// Appends `val` to the words array.
fn append_u128_to_words_array(
ref words_arr: Array<u32>,
val: u128,
ref last_word: u32,
ref last_word_len: u32,
mut shift: u32,
) {
words_arr
.append(
(last_word.into() * one_shift_left_bytes_u128(4 - last_word_len)
+ val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
if shift != 3 {
shift = shift - 4;
words_arr
.append(
(val / one_shift_left_bytes_u128(shift) % one_shift_left_bytes_u128(4))
.try_into()
.unwrap(),
);
}
last_word = (val % one_shift_left_bytes_u128(shift)).try_into().unwrap();
last_word_len = shift;
}
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