DKIM Signature Header Validator | iN2 Tools

Run cryptographic verification check on a DKIM signature from raw email headers against the active public DNS key.

DKIM Signature Validator & Header Inspector

Validate DomainKeys Identified Mail (DKIM) digital signatures in raw email headers (RFC 6376). Fetch public keys from DNS, verify body hashes (bh), check RSA/Ed25519 key lengths, and verify canonicalization.

What Is DomainKeys Identified Mail (DKIM / RFC 6376)?

DKIM (DomainKeys Identified Mail) (RFC 6376) is an email authentication method that attaches a cryptographic digital signature to outgoing email headers using asymmetric public-private key cryptography.

Key Components of a DKIM Signature

  • d= (Signing Domain): The domain claiming responsibility for sending the email payload.
  • s= (Selector): The selector prefix used to construct the DNS TXT query key path: [selector]._domainkey.[domain].
  • bh= (Body Hash): SHA-256 (or SHA-1) hash digest of the canonicalized email body text.
  • b= (Digital Signature): The RSA (or Ed25519) digital signature covering specified header fields.

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