Requesting a private PKI certificate - AWS Certificate Manager

Requesting a private PKI certificate

If you have access to an existing private CA created by AWS Private CA, ACM can request a certificate suited for use in your private PKI . The CA may either reside in your account or be shared with you by a different account. For information about creating a private CA, see Create a Private Certificate Authority.

Certificates signed by a private CA are not trusted by default, and ACM does not support any form of validation for them. Consequently, an administrator must take action to install them in your organizations's client trust stores.

Private ACM certificates follow the X.509 standard and are subject to the following restrictions:

  • Names: You must use DNS-compliant subject names. For more information, see Domain Names.

  • Algorithm: For encryption, the certificate private key algorithm must be either 2048-bit RSA, 256-bit ECDSA, or 384-bit ECDSA.


    The specified signing algorithm family (RSA or ECDSA) must match the algorithm family of the CA's secret key.

  • Expiration: Each certificate is valid for 13 months (395 days). The end date of the signing CA certificate must exceed the end date of the requested certificate, or else the certificate request will fail.

  • Renewal: ACM attempts to renew a private certificate automatically after 11 months.

The private CA used to sign the end-entity certificates is subject to its own restrictions:

  • The CA must have a status of Active.

  • The CA private key algorithm must be RSA 2048 or RSA 4096.


Unlike publicly trusted certificates, certificates signed by a private CA do not require validation.

Configuring access to a private CA

You can use AWS Private CA to sign your ACM certificates in either of two cases:

  • Single account: The signing CA and the ACM certificate that is issued reside in the same AWS account.

    For single-account issuance and renewals to be enabled, the AWS Private CA administrator must grant permission to the ACM service principal to create, retrieve, and list certificates. This is done using the AWS Private CA API action CreatePermission or the AWS CLI command create-permission. The account owner assigns these permissions to an IAM user, group, or role that is responsible for issuing certificates.

  • Cross-account: The signing CA and the ACM certificate that is issued reside in different AWS accounts, and access to the CA has been granted to the account where the certificate resides.

    To enable cross-account issuance and renewals, the AWS Private CA administrator must attach a resource-based policy to the CA using the AWS Private CA API action PutPolicy or the AWS CLI command put-policy. The policy specifies principals in other accounts that are allowed limited access to the CA. For more information, see Using a Resource Based Policy with ACM Private CA.

    The cross-account scenario also requires ACM to set up a service-linked role (SLR) to interact as a principal with the PCA policy. ACM creates the SLR automatically while issuing the first certificate.

    ACM might alert you that it cannot determine whether an SLR exists on your account. If the required iam:GetRole permission has already been granted to the ACM SLR for your account, then the alert will not recur after the SLR is created. If it does recur, then you or your account administrator might need to grant the iam:GetRole permission to ACM, or associate your account with the ACM-managed policy AWSCertificateManagerFullAccess.

    For more information, see Using a Service Linked Role with ACM.


Your ACM certificate must be actively associated with a supported AWS service before it can be automatically renewed. For information about the resources that ACM supports, see Services integrated with AWS Certificate Manager.

Request a private PKI certificate using the ACM console

  1. Sign into the AWS Management Console and open the ACM console at

    Choose Request a certificate.

  2. On the Request certificate page, choose Request a private certificate and Next to continue.

  3. In the Certificate authority details section, click the Certificate authority menu and choose one of the available private CAs. If the CA is shared from another account, the ARN is prefaced by ownership information.

    Details about the CA are displayed to help you verify that you have chosen the correct one:

    • Owner

    • Type

    • Common name (CN)

    • Organization (O)

    • Organization unit (OU)

    • Country name (C)

    • State or province

    • Locality name

  4. In the Domain names section, type your domain name. You can use a fully qualified domain name (FQDN), such as, or a bare or apex domain name such as You can also use an asterisk (*) as a wild card in the leftmost position to protect several site names in the same domain. For example, * protects, and The wild-card name will appear in the Subject field and in the Subject Alternative Name extension of the ACM certificate.


    When you request a wild-card certificate, the asterisk (*) must be in the leftmost position of the domain name and can protect only one subdomain level. For example, * can protect, and, but it cannot protect Also note that * protects only the subdomains of, it does not protect the bare or apex domain ( To protect both, see the next step

    Optionally, choose Add another name to this certificate and type the name in the text box. This is useful for authenticating both a bare or apex domain (such as and its subdomains such as *

  5. In the Key algorithm section, chose one of the three available algorithms:

    • RSA 2048 (default)

    • ECDSA P 256

    • ECDSA P 384

    For information to help you choose an algorithm, see Key algorithms.

  6. In the Tags section, you can optionally tag your certificate. Tags are key-value pairs that serve as metadata for identifying and organizing AWS resources. For a list of ACM tag parameters and for instructions on how to add tags to certificates after creation, see Tagging AWS Certificate Manager certificates.

  7. In the Certificate renewal permissions section, acknowledge the notice about certificate renewal permissions. These permissions allow automatic renewal of private PKI certificates that you sign with the selected CA. For more information, see Using a Service Linked Role with ACM.

  8. After providing all of the required information, choose Request. The console returns you to the certificate list, where you can view your new certificate.


    Depending on how you have ordered the list, a certificate you are looking for might not be immediately visible. You can click the black triangle at right to change the ordering. You can also navigate through multiple pages of certificates using the page numbers at upper-right.

Request a private PKI certificate using the CLI

Use the request-certificate command to request a private certificate in ACM.


When you request a private PKI certificate signed by a CA from AWS Private CA, the specified signing algorithm family (RSA or ECDSA) must match the algorithm family of the CA's secret key.

aws acm request-certificate \ --domain-name \ --idempotency-token 12563 \ --certificate-authority-arn arn:aws:acm-pca:Region:444455556666:\ certificate-authority/CA_ID

This command outputs the Amazon Resource Name (ARN) of your new private certificate.

{ "CertificateArn": "arn:aws:acm:Region:444455556666:certificate/certificate_ID" }

In most cases, ACM automatically attaches a service-linked role (SLR) to your account the first time that you use a shared CA. The SLR enables automatic renewal of end-entity certificates that you issue. To check whether the SLR is present, you can query IAM with the following command:

aws iam get-role --role-name AWSServiceRoleForCertificateManager

If the SLR is present, the command output should resemble the following:

{ "Role":{ "Path":"/aws-service-role/", "RoleName":"AWSServiceRoleForCertificateManager", "RoleId":"AAAAAAA0000000BBBBBBB", "Arn":"arn:aws:iam::{account_no}:role/aws-service-role/", "CreateDate":"2020-08-01T23:10:41Z", "AssumeRolePolicyDocument":{ "Version":"2012-10-17", "Statement":[ { "Effect":"Allow", "Principal":{ "Service":"" }, "Action":"sts:AssumeRole" } ] }, "Description":"SLR for ACM Service for accessing cross-account Private CA", "MaxSessionDuration":3600, "RoleLastUsed":{ "LastUsedDate":"2020-08-01T23:11:04Z", "Region":"ap-southeast-1" } } }

If the SLR is missing, see Using a Service Linked Role with ACM.