Compute the hash of a string using a hash function

Compute an HMAC hash given a message, secret and hash function

If you plan to send webhook requests to a third-party from Prismatic, you can use the **Compute HMAC Hash** action to compute the HMAC hash of a given string using a **secret key**.


Compute hashes of strings using common hash functions

The **Hash** component allows you to compute the hash of a string using a variety of common hash functions (MD5, SHA256, etc).


Validate a payload using an HMAC hash function

HMAC (or hash-based message authentication code) is an authentication mechanism that allows you verify that incoming webhook messages are genuine.

#### How does HMAC work?

An external system (yours or a third-party) produces a cryptographic hash of the webhook payload's body using a secret key, and sends the hash as an HTTP header along with the webhook request.
Only the external system and your integration know the secret key.

This trigger, then, uses the secret key to produce a hash of the received payload.
If the hash generated in the trigger matches the hash sent as a header, the payload is processed.
If the hashes do not match, an error is thrown and the integration does not run.
This prevents a bad actor from sending bogus payloads to your instances - they cannot spoof an HMAC hash without the correct signing key.

You can read more about HMAC on our [blog](https://prismatic.io/blog/how-secure-webhook-endpoints-hmac/).

#### Example HMAC Signature

Suppose you would like to sign a JSON payload that reads `{"foo":"bar","baz":123,"buz":false}` using the SHA256 hashing algorithm (you can use a number of hashing algorithms, SHA256 being the most common for HMAC).
You've chosen a secret key of `secret123` (please use a more complex secret!).
You can generate a hash in NodeJS using the `crypto` module:

```js title="Compute an HMAC hash in a third-party system"
const body = '{"foo":"bar","baz":123,"buz":false}';
const hmac = crypto.createHmac("sha256", "secret123");
const hash = hmac.update(body, "utf-8").digest("hex");
// Generates 44cfc2defd77a70bedef0228634c45800fce1e678174895e984bd608c221bdb8
```

Most modern languages have HMAC libraries: [NodeJS](https://nodejs.org/api/crypto.html), [Python](https://docs.python.org/3/library/hmac.html), [PHP](https://www.php.net/manual/en/function.hash-hmac.php), [.NET C#](https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.hmac?view=net-6.0).

You can then take that hash and pass it in as a header in a webhook invocation request:

```bash
curl https://hooks.prismatic.io/example \
  --request POST \
  --header "my-hmac-hash: 44cfc2defd77a70bedef0228634c45800fce1e678174895e984bd608c221bdb8" \
  --header "content-type: application/json" \
  --data '{"foo":"bar","baz":123,"buz":false}'
```

When you configure your HMAC trigger in Prismatic, then, you can enter `secret123` as your **HMAC Secret Key**, `my-hmac-hash` as your **HMAC Header Name**, and `SHA256` as your **HMAC Algorithm** (you can obviously change those values).


Action Name	Action Description
Compute Hash	Compute the hash of a string using a hash function
Compute HMAC Hash	Compute an HMAC hash given a message, secret and hash function
Compute BLAKE2b512 Hash	Compute the BLAKE2b512 hash of a string
Compute BLAKE2s256 Hash	Compute the BLAKE2s256 hash of a string
Compute MD4 Hash	Compute the MD4 hash of a string
Compute MD5 Hash	Compute the MD5 hash of a string
Compute MD5-SHA1 Hash	Compute the MD5-SHA1 hash of a string
Compute RIPEMD160 Hash	Compute the RIPEMD160 hash of a string
Compute SHA1 Hash	Compute the SHA1 hash of a string
Compute SHA224 Hash	Compute the SHA224 hash of a string
Compute SHA256 Hash	Compute the SHA256 hash of a string
Compute SHA3-224 Hash	Compute the SHA3-224 hash of a string
Compute SHA3-256 Hash	Compute the SHA3-256 hash of a string
Compute SHA3-384 Hash	Compute the SHA3-384 hash of a string
Compute SHA3-512 Hash	Compute the SHA3-512 hash of a string
Compute SHA384 Hash	Compute the SHA384 hash of a string
Compute SHA512 Hash	Compute the SHA512 hash of a string
Compute SHA512-224 Hash	Compute the SHA512-224 hash of a string
Compute SHA512-256 Hash	Compute the SHA512-256 hash of a string
Compute SM3 Hash	Compute the SM3 hash of a string
Compute whirlpool Hash	Compute the whirlpool hash of a string

Hash Component

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About the Hash Component

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