I asked the question "what's smtp dane in modern email system?" to
chatgpt. Here is gpt's answer which I think to be valueful. so I share here.
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SMTP DANE (DNS-based Authentication of Named Entities) is a security
protocol used in modern email systems to ensure secure and authenticated
email delivery. It leverages DNSSEC (DNS Security Extensions) to verify
the authenticity of TLS (Transport Layer Security) certificates used by
email servers.
Here’s a breakdown of SMTP DANE and its role in secure email communication:
1. **DNSSEC**: DNSSEC is an extension to the DNS (Domain Name System)
that adds security to prevent certain types of attacks, such as DNS
spoofing or cache poisoning. DNSSEC ensures that the DNS responses are
authentic and have not been tampered with.
2. **TLS (Transport Layer Security)**: TLS is a protocol that provides
encryption for data transmitted over the internet, ensuring privacy and
data integrity between communicating applications. For email, this means
encrypting the communication between email servers.
3. **DANE (DNS-based Authentication of Named Entities)**: DANE uses
DNSSEC to publish information about the TLS certificates that should be
used for a particular service, such as an email server. This helps to
authenticate the email server and ensures that the connection is
encrypted with a valid certificate.
### How SMTP DANE Works:
1. **DNSSEC Validation**: The sending email server performs a
DNSSEC-secured lookup to retrieve the TLSA (Transport Layer Security
Authentication) record for the receiving email server. The TLSA record
contains information about the expected TLS certificate.
2. **Certificate Verification**: The sending server compares the TLS
certificate presented by the receiving server during the TLS handshake
with the information in the TLSA record. If the certificate matches, the
connection is considered secure and authenticated.
3. **Secure Communication**: Once the certificate is verified, the
sending server can establish an encrypted TLS connection to the
receiving server, ensuring the email is transmitted securely.
### Benefits of SMTP DANE:
- **Enhanced Security**: SMTP DANE ensures that the email communication
is encrypted and the receiving server is authenticated, reducing the
risk of man-in-the-middle attacks and eavesdropping.
- **Protection Against Spoofing**: By verifying the TLS certificate
against DNSSEC-signed records, SMTP DANE helps prevent email spoofing
and server impersonation.
- **Improved Trust**: Users and organizations can have greater
confidence that their email communications are secure and have not been
intercepted or altered.
### Adoption and Challenges:
- **Adoption**: While SMTP DANE offers significant security benefits,
its adoption has been relatively slow. This is partly due to the need
for widespread implementation of DNSSEC, which is a prerequisite for DANE.
- **Configuration Complexity**: Setting up DNSSEC and DANE can be
complex and may require changes to the DNS infrastructure and email
server configuration.
- **Support**: Not all email servers and providers currently support
SMTP DANE, which can limit its effectiveness in providing end-to-end
email security.
In summary, SMTP DANE is a valuable protocol for enhancing the security
of email communication by leveraging DNSSEC to authenticate TLS
certificates, ensuring secure and trusted email delivery.
But, crucially, also a local*validating* resolver is a pre-requisite,
--
Jeff Pang
jeffp...@aol.com
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