# RIPEMD-160 Final Value Construction and Output

{% embed url="<https://youtu.be/HjHMqILYxOk>" %}

#### Building the Final Value

The last step of the **RIPEMD-160 hash function** is to take the **final chaining values** (the working registers after compression) and combine them into the **final 160-bit hash**.

In Go, this is handled by `PrintFinalHashValuesInHex`:

```
func PrintFinalHashValuesInHex(hashValues []uint32) string {
    finalValue := make([]byte, 20)

    binary.LittleEndian.PutUint32(finalValue[0:],  hashValues[0])
    binary.LittleEndian.PutUint32(finalValue[4:],  hashValues[1])
    binary.LittleEndian.PutUint32(finalValue[8:],  hashValues[2])
    binary.LittleEndian.PutUint32(finalValue[12:], hashValues[3])
    binary.LittleEndian.PutUint32(finalValue[16:], hashValues[4])

    return fmt.Sprintf("%x", finalValue)
}
```

👉 The five 32-bit chaining values are **concatenated in Little-Endian order**, producing a **20-byte (160-bit) result**.

***

#### Printing the Output

The result is returned to the main program and printed to **standard output**:

```
func main() {
    fi, _ := os.Stdin.Stat()

    if (fi.Mode() & os.ModeCharDevice) == 0 {
        reader := bufio.NewReader(os.Stdin)
        input, _ := reader.ReadString('\n')
        input = strings.TrimSuffix(input, "\n")
        fmt.Println(GetHash(input))
    } else {
        if len(os.Args) > 1 && len(os.Args) < 3 {
            fmt.Println(GetHash(os.Args[1]))
        } else {
            fmt.Println("Please provide a single input string")
        }
    }
}
```

&#x20;

* If input is piped in, the program reads from **STDIN**.
* If input is provided as a **command-line argument**, it hashes that string.
* Otherwise, it prompts the user for correct usage.

***

#### Verifying the Output

We can check correctness against the **test vectors** from Dobbertin et al.’s original paper:

* Input: `"abc"`
  * Expected Output:

```
8eb208f7e05d987a9b044a8e98c6b087f15a0bfc
```

* * Actual Run:

```
./ripemd160-example abc
8eb208f7e05d987a9b044a8e98c6b087f15a0bfc
```

* Input: `"a"` repeated 1 million times
  * Expected Output:

```
52783243c1697bdbe16d37f97f68f08325dc1528
```

* * Actual Run:

```
printf a%0.s {1..1000000} | ./ripemd160-example
52783243c1697bdbe16d37f97f68f08325dc1528
```

***

✅ **Summary:**

* The **final chaining values** are concatenated in **Little-Endian order** to form the 160-bit hash.
* The result is returned as a **hex string** and printed to output.
* Verification against **published test vectors** confirms the correctness of the RIPEMD-160 implementation.


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