Selecting Key Types for Email Authentication on Cisco ESA

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When configuring email authentication on Cisco Email Security Appliance (ESA), it is important to select the appropriate key types on the signing profile. The two key types that should be selected are DKIM and DomainKeys.

DKIM stands for DomainKeys Identified Mail and is a widely-used email authentication protocol that allows senders to digitally sign their messages. The digital signature provides a means of verifying the authenticity of the message and its source. When DKIM is enabled on the Cisco ESA, the appliance will use the private key to sign outgoing messages, and the recipient's email server will use the public key to verify the signature. This helps prevent email spoofing and protects against email phishing attacks.

DomainKeys is an older email authentication protocol that was used before DKIM became widely adopted. It is similar to DKIM in that it uses digital signatures to authenticate messages. However, it uses a different algorithm and key type than DKIM. When DomainKeys is enabled on the Cisco ESA, the appliance will use the private key to sign outgoing messages, and the recipient's email server will use the public key to verify the signature.

Public and private keys are a critical component of both DKIM and DomainKeys. Public keys are used to verify digital signatures, while private keys are used to create them. When configuring email authentication on Cisco ESA, it is important to select the appropriate key types to ensure that messages are properly authenticated and that email spoofing and phishing attacks are prevented. Symmetric keys are not typically used in email authentication, and thus should not be selected on the signing profile.