Imports a signed private CA certificate into ACM Private CA. This action is used when you are using a chain of trust whose root is located outside ACM Private CA. Before you can call this action, the following preparations must in place:
- In ACM Private CA, call the CreateCertificateAuthority action to create the private CA that you plan to back with the imported certificate.
- Call the GetCertificateAuthorityCsr action to generate a certificate signing request (CSR).
- Sign the CSR using a root or intermediate CA hosted by either an on-premises PKI hierarchy or by a commercial CA.
- Create a certificate chain and copy the signed certificate and the certificate chain to your working directory.
ACM Private CA supports three scenarios for installing a CA certificate:
- Installing a certificate for a root CA hosted by ACM Private CA.
- Installing a subordinate CA certificate whose parent authority is hosted by ACM Private CA.
- Installing a subordinate CA certificate whose parent authority is externally hosted.
The following additional requirements apply when you import a CA certificate.
Enforcement of Critical Constraints
- Only a self-signed certificate can be imported as a root CA.
- A self-signed certificate cannot be imported as a subordinate CA.
- Your certificate chain must not include the private CA certificate that you are importing.
- Your root CA must be the last certificate in your chain. The subordinate certificate, if any, that your root CA signed must be next to last. The subordinate certificate signed by the preceding subordinate CA must come next, and so on until your chain is built.
- The chain must be PEM-encoded.
- The maximum allowed size of a certificate is 32 KB.
- The maximum allowed size of a certificate chain is 2 MB.
ACM Private CA allows the following extensions to be marked critical in the imported CA certificate or chain.
- Basic constraints (must be marked critical)
- Subject alternative names
- Key usage
- Extended key usage
- Authority key identifier
- Subject key identifier
- Issuer alternative name
- Subject directory attributes
- Subject information access
- Certificate policies
- Policy mappings
- Inhibit anyPolicy
ACM Private CA rejects the following extensions when they are marked critical in an imported CA certificate or chain.
- Name constraints
- Policy constraints
- CRL distribution points
- Authority information access
- Freshest CRL
- Any other extension