We only know that the password of a safe consists of $7$ different digits. The safe will open if we enter $7$ different digits, and one of them matches the corresponding digit of the password. Can we open this safe in less than $7$ attempts?

[i](5 points for Juniors and 4 points for Seniors)[/i]
To determine if we can open the safe in less than 7 attempts, we need to ensure that each attempt has at least one digit in the correct position. We will use a strategy to cover all possible digits in each position over multiple attempts.

1. **Understanding the Problem:**
   - The password consists of 7 different digits.
   - We need to find a sequence of attempts such that in each attempt, at least one digit matches the corresponding digit in the password.

2. **Constructing the Attempts:**
   - We will construct 6 different sequences of 7 digits each.
   - Each sequence will be designed to ensure that at least one digit matches the corresponding digit in the password.

3. **Modeling the Attempts:**
   - Let's denote the password as \( P = (p_1, p_2, p_3, p_4, p_5, p_6, p_7) \).
   - We will create 6 sequences such that each sequence has a unique digit in each position.

4. **Sequence Construction:**
   - Consider the following sequences:
     \[
     \begin{array}{ccccccc}
     1 & 2 & 3 & 4 & 5 & 0 & 7 \\
     2 & 3 & 4 & 5 & 6 & 0 & 8 \\
     3 & 4 & 5 & 6 & 1 & 0 & 9 \\
     4 & 5 & 6 & 1 & 2 & 7 & 8 \\
     5 & 6 & 1 & 2 & 3 & 7 & 9 \\
     6 & 1 & 2 & 3 & 4 & 8 & 9 \\
     \end{array}
     \]

5. **Verification:**
   - For each position \( i \) (from 1 to 7), the digit in that position across the 6 sequences covers all possible digits from 0 to 9.
   - This ensures that for any given password, at least one of the sequences will have a digit that matches the corresponding digit in the password.

6. **Contradiction Argument:**
   - Suppose our model does not work. Then, for each position \( i \), the digit \( p_i \) must be one of the digits that appear in the same position across all 6 sequences.
   - However, since each sequence has a unique digit in each position, this would imply that \( p_i \) must be one of the digits in the set \(\{0, 7, 8, 9\}\) for some positions.
   - This leads to a contradiction because there are only 4 digits in the set \(\{0, 7, 8, 9\}\), but we need to cover 7 positions.

Therefore, the model works, and we can open the safe in 6 attempts.

The final answer is \( \boxed{ 6 } \) attempts.