kumo.dkim.rsa_sha256_signer {PARAMS}
Create a DKIM signer that uses RSA SHA256.
-- Called once the body has been received.
-- For multi-recipient mail, this is called for each recipient.
kumo.on('smtp_server_message_received', function(msg)
local signer = kumo.dkim.rsa_sha256_signer {
domain = msg:from_header().domain,
selector = 'default',
headers = { 'From', 'To', 'Subject' },
key = 'example-private-dkim-key.pem',
}
msg:dkim_sign(signer)
end)
PARAMS is a lua table that can have the following keys:
domain
Required. The domain for which the mail is being signed.
selector
Required. The selector used for signing
headers
Required. The list of headers which should be signed.
atps
Optional string. Allows setting the Authorized Third-Party signature.
atpsh
Optional string. Set the Authorized Third-Party Signature hashing algorithm.
agent_user_identifier
Optional string. Sets the Agent of User Identifier (AUID) to use for signing.
expiration
Optional number. Sets the number of seconds from now to use for the signature expiration.
body_length
Optional boolean. If true, the body length will be included
in the signature.
reporting
Optional boolean. If true, the signature will be marked as
requesting reports from the receiver/verifier.
header_canonicalization
Specify the canonicalization method to be used when hashing message headers. Can be one of:
"Relaxed"- this is the default"Simple"
body_canonicalization
Specify the canonicalization method to be used when hashing message body. Can be one of:
"Relaxed"- this is the default"Simple"
key
Required. Specify the signing key data.
The value is a KeySource.
The key data must be either RSA PEM or a PKCS8 PEM encoded.
local file_signer = kumo.dkim.rsa_sha256_signer {
domain = msg:from_header().domain,
selector = 'default',
headers = { 'From', 'To', 'Subject' },
key = '/path/to/example-private-dkim-key.pem',
}
Tip
The KeySource page explains how to read from HashiCorp Vault or from an arbitrary source of data.
ttl
Optional number. Specifies the time-to-live (TTL) in KumoMTA's DKIM signer
cache. The default is 300 seconds.
Each call to this function with the same parameters is cached for up to the specified TTL in order to avoid the overhead of repeatedly load the key from disk.
Created: 2023-02-25