---
title: The dh_params Resource
platform: linux
---

# dh_params

Use the `dh_params` Chef InSpec audit resource to test Diffie-Hellman (DH) parameters.

<br>

## Availability

### Installation

This resource is distributed along with Chef InSpec itself. You can use it automatically.

### Version

This resource first became available in v1.19.0 of InSpec.

## Syntax

A `dh_params` resource block declares a parameter file to be tested.

    describe dh_params('/path/to/file.dh_pem') do
      it { should be_dh_params }
      it { should be_valid }
      its('generator') { should eq 2 }
      its('modulus') { should eq '00:91:a0:15:89:e5:bc:38:93:12:02:fc:...' }
      its('prime_length') { should eq 2048 }
      its('pem') { should eq '-----BEGIN DH PARAMETERS...' }
      its('text') { should eq 'PKCS#3 DH Parameters: (2048 bit)...' }
    end

<br>

## Properties

* `generator`, `modulus`, `prime_length`, `pem`, `text`

<br>

## Property Examples

### generator (Integer)

Verify generator used for the Diffie-Hellman operation:

    describe dh_params('/path/to/file.dh_pem') do
      its('generator') { should eq 2 }
    end

### modulus (String)

Verify prime modulus used for the Diffie-Hellman operation:

    describe dh_params('/path/to/file.dh_pem') do
      its('modulus') { should eq '00:91:a0:15:89:e5:bc:38:93:12:02:fc:...' }
    end

Example using multi-line string:

```ruby
describe dh_params('/path/to/file.dh_pem') do
  its('modulus') do
    # regex removes all whitespace
    should eq <<-EOF.gsub(/[[:space:]]+/, '')
      00:91:a0:15:89:e5:bc:38:93:12:02:fc:91:a2:85:
      f7:f7:29:63:2e:d3:4e:7a:86:f7:ee:84:fe:42:d0:
      48:bc:9c:91:d5:54:f8:78:1d:c0:41:78:a2:c4:ac:
      1a:24:8b:9d:88:55:98:0b:ac:a7:23:eb:c2:aa:2b:
      2e:a9:f9:af:d4:8e:4e:11:bc:7f:35:a2:ac:da:3a:
      ef:f0:25:6c:9a:a4:fd:00:28:76:86:2c:57:87:67:
      30:5d:b1:d6:5b:22:8f:72:a1:ea:de:8b:ef:9e:33:
      1a:40:92:68:85:02:54:02:09:fa:c0:60:c1:3c:4e:
      28:26:db:ed:25:8e:38:21:56:40:dc:c0:c0:66:1f:
      2b:32:c3:b4:78:a9:26:94:ea:f7:41:28:b2:f5:5b:
      01:38:0c:46:09:85:26:4d:69:12:8d:95:0f:35:e2:
      e6:4e:47:3a:86:dd:8a:b2:fe:45:15:27:d8:59:c2:
      3c:f4:62:ff:5f:74:e9:77:92:50:47:36:2b:05:57:
      60:ee:7b:a1:60:cc:1c:7a:2b:77:18:8a:37:f7:c7:
      31:3e:15:cb:15:7f:7b:66:96:fb:c6:be:7d:d6:03:
      5e:0d:60:75:2b:5b:62:2a:a3:37:b6:34:f9:fe:96:
      4c:f6:c5:e3:a1:52:af:01:c1:4f:c7:42:a0:be:ed:
      cd:13
    EOF
  end
end
```

### prime_length (Integer)

Verify length of prime modulus used for the Diffie-Hellman operation:

    describe dh_params('/path/to/file.dh_pem') do
      its('prime_length') { should eq 2048 }
    end

### pem (String)

Verify `pem` output of DH parameters:

    describe dh_params('/path/to/file.dh_pem') do
      its('pem') { should eq '-----BEGIN DH PARAMETERS...' }
    end

Example using multi-line string:

```ruby
its('pem') do
  # regex removes all leading spaces
  should eq <<-EOF.gsub(/^[[:blank:]]+/, '')
    -----BEGIN DH PARAMETERS-----
    MIIBCAKCAQEAkaAVieW8OJMSAvyRooX39yljLtNOeob37oT+QtBIvJyR1VT4eB3A
    QXiixKwaJIudiFWYC6ynI+vCqisuqfmv1I5OEbx/NaKs2jrv8CVsmqT9ACh2hixX
    h2cwXbHWWyKPcqHq3ovvnjMaQJJohQJUAgn6wGDBPE4oJtvtJY44IVZA3MDAZh8r
    MsO0eKkmlOr3QSiy9VsBOAxGCYUmTWkSjZUPNeLmTkc6ht2Ksv5FFSfYWcI89GL/
    X3Tpd5JQRzYrBVdg7nuhYMwceit3GIo398cxPhXLFX97Zpb7xr591gNeDWB1K1ti
    KqM3tjT5/pZM9sXjoVKvAcFPx0Kgvu3NEwIBAg==
    -----END DH PARAMETERS-----
  EOF
end
```

Verify via `openssl dhparam` command:

    $ openssl dhparam -in /path/to/file.dh_pem
    -----BEGIN DH PARAMETERS-----
    MIIBCAKCAQEAkaAVieW8OJMSAvyRooX39yljLtNOeob37oT+QtBIvJyR1VT4eB3A
    QXiixKwaJIudiFWYC6ynI+vCqisuqfmv1I5OEbx/NaKs2jrv8CVsmqT9ACh2hixX
    h2cwXbHWWyKPcqHq3ovvnjMaQJJohQJUAgn6wGDBPE4oJtvtJY44IVZA3MDAZh8r
    MsO0eKkmlOr3QSiy9VsBOAxGCYUmTWkSjZUPNeLmTkc6ht2Ksv5FFSfYWcI89GL/
    X3Tpd5JQRzYrBVdg7nuhYMwceit3GIo398cxPhXLFX97Zpb7xr591gNeDWB1K1ti
    KqM3tjT5/pZM9sXjoVKvAcFPx0Kgvu3NEwIBAg==
    -----END DH PARAMETERS-----

### text (String)

Verify human-readable text output of DH parameters:

    describe dh_params('/path/to/file.dh_pem') do
      its('text') { should eq 'PKCS#3 DH Parameters: (2048 bit)...' }
    end

Example using multi-line string:

```ruby
its('text') do
  # regex removes 2 leading spaces
  should eq <<-EOF.gsub(/^[[:blank:]]{2}/, '')
    PKCS#3 DH Parameters: (2048 bit)
        prime:
            00:91:a0:15:89:e5:bc:38:93:12:02:fc:91:a2:85:
            f7:f7:29:63:2e:d3:4e:7a:86:f7:ee:84:fe:42:d0:
            48:bc:9c:91:d5:54:f8:78:1d:c0:41:78:a2:c4:ac:
            1a:24:8b:9d:88:55:98:0b:ac:a7:23:eb:c2:aa:2b:
            2e:a9:f9:af:d4:8e:4e:11:bc:7f:35:a2:ac:da:3a:
            ef:f0:25:6c:9a:a4:fd:00:28:76:86:2c:57:87:67:
            30:5d:b1:d6:5b:22:8f:72:a1:ea:de:8b:ef:9e:33:
            1a:40:92:68:85:02:54:02:09:fa:c0:60:c1:3c:4e:
            28:26:db:ed:25:8e:38:21:56:40:dc:c0:c0:66:1f:
            2b:32:c3:b4:78:a9:26:94:ea:f7:41:28:b2:f5:5b:
            01:38:0c:46:09:85:26:4d:69:12:8d:95:0f:35:e2:
            e6:4e:47:3a:86:dd:8a:b2:fe:45:15:27:d8:59:c2:
            3c:f4:62:ff:5f:74:e9:77:92:50:47:36:2b:05:57:
            60:ee:7b:a1:60:cc:1c:7a:2b:77:18:8a:37:f7:c7:
            31:3e:15:cb:15:7f:7b:66:96:fb:c6:be:7d:d6:03:
            5e:0d:60:75:2b:5b:62:2a:a3:37:b6:34:f9:fe:96:
            4c:f6:c5:e3:a1:52:af:01:c1:4f:c7:42:a0:be:ed:
            cd:13
        generator: 2 (0x2)
    EOF
end
```

Verify via `openssl dhparam` command:

    $ openssl dhparam -in /path/to/file.dh_pem -noout -text
    PKCS#3 DH Parameters: (2048 bit)
        prime:
            00:91:a0:15:89:e5:bc:38:93:12:02:fc:91:a2:85:
            f7:f7:29:63:2e:d3:4e:7a:86:f7:ee:84:fe:42:d0:
            48:bc:9c:91:d5:54:f8:78:1d:c0:41:78:a2:c4:ac:
            1a:24:8b:9d:88:55:98:0b:ac:a7:23:eb:c2:aa:2b:
            2e:a9:f9:af:d4:8e:4e:11:bc:7f:35:a2:ac:da:3a:
            ef:f0:25:6c:9a:a4:fd:00:28:76:86:2c:57:87:67:
            30:5d:b1:d6:5b:22:8f:72:a1:ea:de:8b:ef:9e:33:
            1a:40:92:68:85:02:54:02:09:fa:c0:60:c1:3c:4e:
            28:26:db:ed:25:8e:38:21:56:40:dc:c0:c0:66:1f:
            2b:32:c3:b4:78:a9:26:94:ea:f7:41:28:b2:f5:5b:
            01:38:0c:46:09:85:26:4d:69:12:8d:95:0f:35:e2:
            e6:4e:47:3a:86:dd:8a:b2:fe:45:15:27:d8:59:c2:
            3c:f4:62:ff:5f:74:e9:77:92:50:47:36:2b:05:57:
            60:ee:7b:a1:60:cc:1c:7a:2b:77:18:8a:37:f7:c7:
            31:3e:15:cb:15:7f:7b:66:96:fb:c6:be:7d:d6:03:
            5e:0d:60:75:2b:5b:62:2a:a3:37:b6:34:f9:fe:96:
            4c:f6:c5:e3:a1:52:af:01:c1:4f:c7:42:a0:be:ed:
            cd:13
        generator: 2 (0x2)

<br>

## Matchers

For a full list of available matchers, please visit our [matchers page](https://www.inspec.io/docs/reference/matchers/).

### be_valid

Verify whether DH parameters are valid:

    describe dh_params('/path/to/file.dh_pem') do
      it { should be_valid }
    end

### be\_dh\_params

    describe dh_params('/path/to/file.dh_pem') do
        it { should be_dh_params}
    end