How to quickly identify DKIM key length (1024 or 2048)?
Summary
What email marketers say8Marketer opinions
Email marketer from UnlockTheInbox shares that in the DNS TXT record for DKIM, the key size isn't directly visible, as the record contains the public key itself. To find the key size, you must extract the public key from the DNS record and then use a tool like OpenSSL to analyze it.
Email marketer from SuperUser recommends using online DKIM validators like dkimvalidator.com to check the key size, providing a user-friendly alternative to command-line tools.
Email marketer from dkimvalidator.com details you can use dkimvalidator.com to check the DKIM record and it automatically shows you the DKIM key size. You send an email to the specified address, and it will respond with a report that includes DKIM information.
Email marketer from Reddit shares that you can use OpenSSL to determine the key size. Using the command: `openssl rsa -in yourkey.pem -text -noout` will output the key details, including the modulus which represents the key length.
Email marketer from ServerFault answers using OpenSSL to extract the key size. Save the DKIM public key to a file. Next use the command: `openssl rsa -in dkim.public -text -noout`. This will output the public key's details, including the modulus. Check the modulus length to determine the key size.
Email marketer from StackOverflow answers to get the DKIM key size you need to log into your DNS provider and get the string for the DKIM record. Next take the string and put it in a text file. Then using the command line tool OpenSSL run the command to get the details.
Email marketer from MXToolbox states that using their tool you can look up the DKIM record and validate the key size.
Email marketer from Mailhardener describes how to check the key length by retrieving your DKIM record and running the openssl command to retrieve the details and modulus.
What the experts say4Expert opinions
Expert from Email Geeks shares that Wombatmail can be used to identify DKIM key length and provides an example link.
Expert from Email Geeks explains how to use the OpenSSL command on Mac/Unix to identify DKIM key length, providing the command and explaining how to format the key information.
Expert from Email Geeks shares a link to a Python script on GitHub that can be used to identify DKIM key length.
Expert from Spamresource explains that a proper DKIM key requires a key length of 1024 bits or greater.
What the documentation says4Technical articles
Documentation from DigiCert.com explains how to use OpenSSL to check the DKIM key length. They describe the command line steps involving extracting the public key, saving it to a file, and then using openssl rsa -in <keyfile> -text -noout to display the key details, including modulus, which indicates the key length.
Documentation from Let's Encrypt Community explain how to show the size of the RSA key. Using OpenSSL, you can use this command: `openssl rsa -in privkey.pem -text | grep Private-Key: | cut -d' ' -f4`. This command will extract the key size in bits.
Documentation from knowledgeadvisor.biz tells you can use a tool to determine if your DKIM key is valid and of the correct length. They show how to check your DKIM key size by using a tool like mail-tester.com.
Documentation from OpenSSL's wiki explains how to display the public key using OpenSSL. Use this command: `openssl rsa -in your_private_key.pem -pubout -outform PEM | openssl rsa -pubin -text -noout` This command gives all the nitty gritty details of your key in a human readable form.