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2024 | MoveCTF

DynamicMatrixTraversal

#move #pascal's triangle

题目

matrix.move 
module dynamic_matrix_traversal::matrix {

    use std::vector;
    use sui::event;
    use sui::object::{Self, UID};
    use sui::transfer;
    use sui::tx_context::{Self, TxContext};

    const TARGET_VALUE_1: u64 = 2794155;
    const TARGET_VALUE_2: u64 = 14365;

    const ERROR_RESULT_1: u64 = 1;
    const ERROR_RESULT_2: u64 = 2;
    const ERROR_PARAM_1: u64 = 3;
    const ERROR_PARAM_2: u64 = 4;

    struct Flag has copy, drop {
        user: address,
        flag: bool
    }

    struct Record has key {
        id: UID,
        count_1: u64,
        count_2: u64,
        count_3: u64,
        count_4: u64
    }


    fun init(ctx: &mut sui::tx_context::TxContext) {
        let record = Record {
            id: object::new(ctx),
            count_1: 0,
            count_2: 0,
            count_3: 0,
            count_4: 0
        };

        transfer::share_object(record);
    }

    fun up(m: u64, n: u64): u64 {
        let f: vector<vector<u64>> = vector::empty();
        let i: u64 = 0;
        while (i < m) {
            let row: vector<u64> = vector::empty();
            let j: u64 = 0;
            while (j < n) {
                if (j == 0 || i == 0) {
                    vector::push_back(&mut row, 1);
                } else {
                    let f1 = *vector::borrow(&f, i - 1);
                    let j1 = *vector::borrow(&row, j - 1);
                    let val = *vector::borrow(&f1, j) + j1;
                    vector::push_back(&mut row, val);
                };
                j = j + 1;
            };
            vector::push_back(&mut f, row);
            i = i + 1;
        };
        let fr = *vector::borrow(&f, m - 1);
        let result = *vector::borrow(&fr, n-1);
        result
    }

    public entry fun execute(record: &mut Record, m: u64, n: u64) {
        if (record.count_1 == 0) {
            let result: u64 = up(m, n);
            assert!(result == TARGET_VALUE_1, ERROR_RESULT_1);
            record.count_1 = m;
            record.count_2 = n;
        } else if (record.count_3 == 0) {
            let result: u64 = up(m, n);
            assert!(result == TARGET_VALUE_2, ERROR_RESULT_2);
            record.count_3 = m;
            record.count_4 = n;
        }
    }

    public entry fun get_flag(record: &Record, ctx: &mut TxContext) {
        assert!(record.count_1 < record.count_3, ERROR_PARAM_1);
        assert!(record.count_2 > record.count_4, ERROR_PARAM_2);
        event::emit(Flag { user: tx_context::sender(ctx), flag: true });
    }

    #[test_only]
    public fun init2(ctx: &mut sui::tx_context::TxContext) {
        init(ctx)
    }
}
Move.toml 
[package]
name = "dynamic_matrix_traversal"
version = "0.0.1"

[dependencies]
Sui = { git = "https://github.com/MystenLabs/sui.git", subdir = "crates/sui-framework/packages/sui-framework", rev = "framework/testnet" }

[addresses]
dynamic_matrix_traversal = "0x0"

解题思路

  • count_1、count_2、count_3 和 count_4 初始值为 \(0\)，最终需要满足 count_1 < count_3 且 count_2 > count_4

  • 通过 execute() 可以分别设置 count_1 & count_2 以及 count_3 & count_4，但 up(m, n) 的执行结果应等于特定的 TARGET_VALUE

    public entry fun execute(record: &mut Record, m: u64, n: u64) {
    if (record.count_1 == 0) {
        let result: u64 = up(m, n);
        assert!(result == TARGET_VALUE_1, ERROR_RESULT_1);
        record.count_1 = m;
        record.count_2 = n;
    } else if (record.count_3 == 0) {
        let result: u64 = up(m, n);
        assert!(result == TARGET_VALUE_2, ERROR_RESULT_2);
        record.count_3 = m;
        record.count_4 = n;
    }
}

  • 函数 up() 输出矩阵第 m 行第 n 列的结果，其中第 1 行第 1 列所有元素均为 \(1\)，随后第 i 行第 j 列的元素为第 i-1 行第 j 列和第 i 行第 j-1 列元素相加的结果

    fun up(m: u64, n: u64): u64 {
    let f: vector<vector<u64>> = vector::empty();
    let i: u64 = 0;
    while (i < m) {
        let row: vector<u64> = vector::empty();
        let j: u64 = 0;
        while (j < n) {
            if (j == 0 || i == 0) {
                vector::push_back(&mut row, 1);
            } else {
                let f1 = *vector::borrow(&f, i - 1);
                let j1 = *vector::borrow(&row, j - 1);
                let val = *vector::borrow(&f1, j) + j1;
                vector::push_back(&mut row, val);
            };
            j = j + 1;
        };
        vector::push_back(&mut f, row);
        i = i + 1;
    };
    let fr = *vector::borrow(&f, m - 1);
    let result = *vector::borrow(&fr, n-1);
    result
}

  • 可以通过暴力求解得到两组 m、n，分别为 m=5,n=89 和 m=169,n=3，恰好能满足题目需求

    def up(m, n):
    if n > m:
        return 0
    f, i = None, 0
    while i < m:
        row = []
        j = 0
        while j < n:
            if j == 0 or i == 0:
                row.append(1)
            else:
                row.append(f[j] + row[j - 1])
            j += 1
        f = row
        i += 1
    return row[n - 1]

for m in range(1, 200):
    for n in range(1, 200):
        if n > m:
            break
        ret = up(m, n)
        if ret in [2794155, 14365]:
            print(m, n)

Exploitation

$ sui client tx-block <digest>  # get Record objectID
$ sui client call --function execute --args <objectId> 5 89 --module matrix --package <packageId> --gas-budget 300000000
$ sui client call --function execute --args <objectId> 169 3 --module matrix --package <packageId> --gas-budget 300000000
$ sui client call --function get_flag --args <objectId> --module matrix --package <packageId> --gas-budget 300000000

Flag

flag{0FhsM2AMrlt9}_DynamicMatrixTraversal

最后更新: 2024年5月26日 23:58:31
Contributors: YanhuiJessica

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