Determining the size of the public key in an SSL/TLS RSA certificate - Amazon CloudFront
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Determining the size of the public key in an SSL/TLS RSA certificate

When you’re using CloudFront alternate domain names and HTTPS, the maximum size of the public key in an SSL/TLS RSA certificate is 2048 bits. (This is the key size, not the number of characters in the public key.) If you use Amazon Certificate Manager for your certificates, although ACM supports larger RSA keys, you cannot use the larger keys with CloudFront.

You can determine the size of the RSA public key by running the following OpenSSL command:

openssl x509 -in path and filename of SSL/TLS certificate -text -noout

Where:

  • -in specifies the path and file name of your SSL/TLS RSA certificate.

  • -text causes OpenSSL to display the length of the RSA public key in bits.

  • -noout prevents OpenSSL from displaying the public key.

Example output:

Public-Key: (2048 bit)