PHP-MAIL-DOMAIN-SIGNER PHP class for Add DKIM-Signature and DomainKey-Signature on your mail

INTRODUCTION

PHP Mail Domain Signer is PHP Class to create DKIM-Signature and DomainKey-Signature for your email data before you sending it on SMTP.

It refer to RFC4871 About DomainKeys Identified Mail (DKIM) Signatures and RFC4870 About Domain-Based Email Authentication Using Public Keys Advertised in the DNS (DomainKeys)

LICENSE

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

FEATURES

PHP Mail Domain Signer had several great features and Easy to integrated into your current mailer script.

Object Oriented
Signing from Raw Email Data
Signing from Custom Array of Headers and Body
Use easy to verifier canonicalization alghoritm "relaxed/relaxed" and "nofws"
Able to return whole signed mail data, or only signed headers in String or Array
You can easly choose only DKIM, DomainKey or both signature
Simple and Fast Implementation of alghoritm

HOW TO USE

PHP Mail Domain Signer was PHP Source code, it only one file class.mailDomainSigner.php to included into your php script then you can easly create new mailDomainSigner object.

Creating Keys

You need to create public and private key to sign your email with PHP Mail Domain Signer.
I reccomended use openssl because it open source and default in some OS like LINUX.

Here how you should create your keys:

  openssl genrsa -out key.priv 384
  openssl rsa -in key.priv -out key.pub -pubout -outform PEM

The first command used to create private key and save it into key.priv,
you can change the key bit-length with other values like 1024.

[NOTE]: According to RFC4870 max length should be 2048bit,
       ( the practical constraint that a 2048-bit key is the largest
         key that fits within a 512-byte DNS UDP response packet )

The second command used to create public key and save it into key.pub.

The Private Key

Contents of Private key key.priv will be used in mailDomainSigner constructor,
you can create new mailDomainSigner with something like

  $mds = &new mailDomainSigner(
    file_get_contents("key.priv"),
    "yourdomain.com",
    "yourselector"
  );

The Public Key

Contents of Public key key.pub will be used in DNS TXT record, Please read
RFC4870-Page12 to know detail about DNS TXT for storing public key.

[NOTE]:
  * Don't use g tag (granularity of the key) if you want to create DomainKey-Signature
  * Remove -----BEGIN PUBLIC KEY----- and -----END PUBLIC KEY----- and all spaces/line characters from public key before add it into TXT record

Setting Your DNS TXT Record

  yourselector._domainkey.yourdomain.com. IN TXT "v=DKIM1;k=rsa;h=sha1;s=email;t=s;p=YOUR_PUBLIC_KEY_DATA_WITHOUT"

If you want to test your dns configuration, you can use php script:

  print_r(dns_get_record("yourselector._domainkey.yourdomain.com",DNS_TXT));

or Linux shell command:

  host -t txt yourselector._domainkey.yourdomain.com

flayder / php-mail-domain-signer

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