package dkim

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Implementation of DKIM in OCaml


Dune Dependency






A library and a binary to verify and sign an email with the DKIM mechanism described by the RFC 6376

Published: 06 Mar 2023



ocaml-dkim is a pure implementation of DKIM in OCaml. It permits to verify and sign an incoming email. It can be use as a SMTP filter service (verify) or as a SMTP submission service (sign).

How to install it?

You must have an OPAM environment. Then, ocaml-dkim can be installed with:

$ opam pin add

How to use it?

ocaml-dkim provides 2 binaries, one to verify, the second to sign an email.

$ dkim.verify test/raw/001.mail

It shows all domains which signed the given email and whether the signature is correct or not (for the last case, it shows you the selector). ocaml-dkim is able to sign an email from a private RSA key and a specific domain such as:

$ dkim.sign -k private-key.pem --selector admin --hostname test/raw/001.mail
DKIM-Signature: ...
Rest of the email

It prints the signed email then. The user is able to use a specific RSA private key or it can use a seed used to generate the RSA private key with the fortuna random number generator.

ocaml-dkim has received funding from the Next Generation Internet Initiative (NGI) within the framework of the DAPSI Project.

Dependencies (18)

  1. x509 >= "0.12.0"
  2. mirage-crypto-pk >= "0.9.2"
  3. mirage-crypto >= "0.9.2"
  4. base64 >= "3.0.0"
  5. fpath
  6. fmt >= "0.8.7"
  7. logs
  8. cmdliner >= "1.1.0"
  9. dns-client >= "6.4.0"
  10. domain-name
  11. hmap
  12. base-unix
  13. astring >= "0.8.5"
  14. ipaddr
  15. digestif >= "0.9.0"
  16. mrmime >= "0.5.0"
  17. dune >= "2.0.0"
  18. ocaml >= "4.08.0"

Dev Dependencies (2)

  1. alcotest with-test
  2. mirage-crypto-rng with-test & >= "0.11.0"

Used by (2)

  1. dkim-bin
  2. dkim-mirage >= "0.5.0"




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