> For the complete documentation index, see [llms.txt](https://sevenval.gitbook.io/flat/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sevenval.gitbook.io/flat/reference/functions/calc-signature.md).

# calc-signature()

```
string calc-signature(string data, string private_key [, string passphrase [, string algorithm]])
```

The `calc-signature` function calculates a signature from the given `input` using the given `private_key` (in PEM format, with or without boundaries). The optional parameter `passphrase` is the pass phrase for decrypting an encrypted private key (the default is the empty string). The optional parameter `algorithm` is the signing algorithm (the default is `SHA256`). The resulting signature is Base64-encoded.

See [Private Key Format](/flat/reference/functions/decrypt.md#private-key-format) for the supported private key format.

## Supported Algorithms

* DSA
* DSA-SHA
* MD2
* MD4
* MD5
* RIPEMD160
* SHA
* SHA1
* SHA224
* SHA256
* SHA384
* SHA512
* dsaEncryption
* dsaWithSHA
* ecdsa-with-SHA1
* md2
* md4
* md5
* ripemd160
* sha
* sha1
* sha224
* sha256
* sha384
* sha512

## Example

```markup
<flow>
  <template>
  {
    {{$data := 'my data' }}
    {{$private_key := 'MIIEvwIBADANBgkqhkiG9w0BA…WygYMAMY8YaiAGwLtBsjrh7S12agaEQg=='}}
    {{$signature := calc-signature($data, $env/MY_PRIVATE_KEY) }}
    {{$signature := calc-signature($data, $private_key, "", "SHA384") }}
    {{$signature := calc-signature($data, $env/MY_ENCRYPTED_PRIVATE_KEY, $env/MY_PASSPHRASE) }}
    {{$signature := calc-signature($data, $env/MY_ENCRYPTED_KEY, $env/MY_PASSPHRASE, 'SHA512') }}
  }
  </template>
<flow>
```

## See also

* [`verify-signature()`](/flat/reference/functions/verify-signature.md)