feat(hints): Add BLAKE2S_FINALIZE hint variant

CHANGELOG.md

@@ -2,6 +2,35 @@
 
 #### Upcoming Changes
 
+* Implement hint variant for finalize_blake2s[#1072](https://github.com/lambdaclass/cairo-rs/pull/1072)
+
+    `BuiltinHintProcessor` now supports the following hint:
+
+     ```python
+    %{
+        # Add dummy pairs of input and output.
+        from starkware.cairo.common.cairo_blake2s.blake2s_utils import IV, blake2s_compress
+
+        _n_packed_instances = int(ids.N_PACKED_INSTANCES)
+        assert 0 <= _n_packed_instances < 20
+        _blake2s_input_chunk_size_felts = int(ids.BLAKE2S_INPUT_CHUNK_SIZE_FELTS)
+        assert 0 <= _blake2s_input_chunk_size_felts < 100
+
+        message = [0] * _blake2s_input_chunk_size_felts
+        modified_iv = [IV[0] ^ 0x01010020] + IV[1:]
+        output = blake2s_compress(
+            message=message,
+            h=modified_iv,
+            t0=0,
+            t1=0,
+            f0=0xffffffff,
+            f1=0,
+        )
+        padding = (message + modified_iv + [0, 0xffffffff] + output) * (_n_packed_instances - 1)
+        segments.write_arg(ids.blake2s_ptr_end, padding)
+        %}
+        ```
+
 * Implement fast_ec_add hint variant [#1087](https://github.com/lambdaclass/cairo-rs/pull/1087)
 
 `BuiltinHintProcessor` now supports the following hint:
@@ -55,7 +84,7 @@
         from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
         x = pack(ids.x, PRIME) % SECP_P
     %}
-    
+
 * Implement hint for `starkware.cairo.common.cairo_keccak.keccak._copy_inputs` as described by whitelist `starknet/security/whitelists/cairo_keccak.json` [#1058](https://github.com/lambdaclass/cairo-rs/pull/1058)
 
     `BuiltinHintProcessor` now supports the following hint:
@@ -114,7 +143,7 @@
 
      `BuiltinHintProcessor` now supports the following hints:
 
-    ```
+    ```python
     %{
        ids.a_lsb = ids.a & 1
        ids.b_lsb = ids.b & 1

cairo_programs/example_blake2s.cairo

@@ -649,5 +649,6 @@ func main{range_check_ptr, bitwise_ptr: BitwiseBuiltin*}() {
     assert output[5] = 1978410869;
     assert output[6] = 3956807281;
     assert output[7] = 3738027290;
+    finalize_blake2s(blake2s_ptr_start, blake2s_ptr);
     return ();
 }

src/hint_processor/builtin_hint_processor/blake2s_utils.rs

@@ -120,6 +120,54 @@ pub fn finalize_blake2s(
     Ok(())
 }
 
+/* Implements Hint:
+        # Add dummy pairs of input and output.
+        from starkware.cairo.common.cairo_blake2s.blake2s_utils import IV, blake2s_compress
+
+        _n_packed_instances = int(ids.N_PACKED_INSTANCES)
+        assert 0 <= _n_packed_instances < 20
+        _blake2s_input_chunk_size_felts = int(ids.BLAKE2S_INPUT_CHUNK_SIZE_FELTS)
+        assert 0 <= _blake2s_input_chunk_size_felts < 100
+
+        message = [0] * _blake2s_input_chunk_size_felts
+        modified_iv = [IV[0] ^ 0x01010020] + IV[1:]
+        output = blake2s_compress(
+            message=message,
+            h=modified_iv,
+            t0=0,
+            t1=0,
+            f0=0xffffffff,
+            f1=0,
+        )
+        padding = (message + modified_iv + [0, 0xffffffff] + output) * (_n_packed_instances - 1)
+        segments.write_arg(ids.blake2s_ptr_end, padding)
+*/
+pub fn finalize_blake2s_v3(
+    vm: &mut VirtualMachine,
+    ids_data: &HashMap<String, HintReference>,
+    ap_tracking: &ApTracking,
+) -> Result<(), HintError> {
+    const N_PACKED_INSTANCES: usize = 7;
+    let blake2s_ptr_end = get_ptr_from_var_name("blake2s_ptr_end", vm, ids_data, ap_tracking)?;
+    let message: [u32; 16] = [0; 16];
+    let mut modified_iv = IV;
+    modified_iv[0] = IV[0] ^ 0x01010020;
+    let output = blake2s_compress(&modified_iv, &message, 0, 0, 0xffffffff, 0);
+    let mut padding = message.to_vec();
+    padding.extend(modified_iv);
+    padding.extend([0, 0xffffffff]);
+    padding.extend(output);
+    let padding = padding.as_slice();
+    let mut full_padding = Vec::<u32>::with_capacity(padding.len() * N_PACKED_INSTANCES);
+    for _ in 0..N_PACKED_INSTANCES - 1 {
+        full_padding.extend_from_slice(padding);
+    }
+    let data = get_maybe_relocatable_array_from_u32(&full_padding);
+    vm.load_data(blake2s_ptr_end, &data)
+        .map_err(HintError::Memory)?;
+    Ok(())
+}
+
 /* Implements Hint:
     B = 32
     MASK = 2 ** 32 - 1

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -1,4 +1,5 @@
 use super::{
+    blake2s_utils::finalize_blake2s_v3,
     ec_recover::{
         ec_recover_divmod_n_packed, ec_recover_product_div_m, ec_recover_product_mod,
         ec_recover_sub_a_b,
@@ -311,6 +312,9 @@ impl HintProcessor for BuiltinHintProcessor {
             hint_code::BLAKE2S_FINALIZE | hint_code::BLAKE2S_FINALIZE_V2 => {
                 finalize_blake2s(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }
+            hint_code::BLAKE2S_FINALIZE_V3 => {
+                finalize_blake2s_v3(vm, &hint_data.ids_data, &hint_data.ap_tracking)
+            }
             hint_code::BLAKE2S_ADD_UINT256 => {
                 blake2s_add_uint256(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -454,6 +454,27 @@ output = blake2s_compress(
 padding = (modified_iv + message + [0, 0xffffffff] + output) * (_n_packed_instances - 1)
 segments.write_arg(ids.blake2s_ptr_end, padding)"#;
 
+pub const BLAKE2S_FINALIZE_V3: &str = r#"# Add dummy pairs of input and output.
+from starkware.cairo.common.cairo_blake2s.blake2s_utils import IV, blake2s_compress
+
+_n_packed_instances = int(ids.N_PACKED_INSTANCES)
+assert 0 <= _n_packed_instances < 20
+_blake2s_input_chunk_size_felts = int(ids.BLAKE2S_INPUT_CHUNK_SIZE_FELTS)
+assert 0 <= _blake2s_input_chunk_size_felts < 100
+
+message = [0] * _blake2s_input_chunk_size_felts
+modified_iv = [IV[0] ^ 0x01010020] + IV[1:]
+output = blake2s_compress(
+    message=message,
+    h=modified_iv,
+    t0=0,
+    t1=0,
+    f0=0xffffffff,
+    f1=0,
+)
+padding = (message + modified_iv + [0, 0xffffffff] + output) * (_n_packed_instances - 1)
+segments.write_arg(ids.blake2s_ptr_end, padding)"#;
+
 pub const BLAKE2S_ADD_UINT256: &str = r#"B = 32
 MASK = 2 ** 32 - 1
 segments.write_arg(ids.data, [(ids.low >> (B * i)) & MASK for i in range(4)])