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# Usage Constraints Dictionary Keys

Use these trust settings keys in a usage constraints dictionary.

## Topics

### Constants

[`var kSecTrustSettingsPolicy: String`](/documentation/Security/kSecTrustSettingsPolicy)

A policy object specifying the certificate verification policy.

[`var kSecTrustSettingsApplication: String`](/documentation/Security/kSecTrustSettingsApplication)

A trusted application reference for the application checking the certificate’s trust settings.

[`var kSecTrustSettingsPolicyString: String`](/documentation/Security/kSecTrustSettingsPolicyString)

A string containing policy-specific data.

[`var kSecTrustSettingsKeyUsage: String`](/documentation/Security/kSecTrustSettingsKeyUsage)

A number specifying the operations for which the encryption key in this certificate can be used.

[`var kSecTrustSettingsAllowedError: String`](/documentation/Security/kSecTrustSettingsAllowedError)

A number which, if encountered during certificate verification, is ignored for that certificate.

[`var kSecTrustSettingsResult: String`](/documentation/Security/kSecTrustSettingsResult)

A number indicating the effective trust setting for this usage constraints dictionary.


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