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Questions tagged [smime]

S/MIME is a protocol for encrypting and signing messages, e.g. emails.

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27 votes
4 answers
3k views

Can a nation-state adversary perform a MITM attack by compelling a CA to issue them with fake certs?

As I understand it, with any encryption system based on a trust chain / CAs (eg SSL, TLS, S/MIME), it would be possible for a nation-state adversary (such as the NSA) to compel the CA to issue them ...
Caesar's user avatar
  • 484
13 votes
3 answers
13k views

What is the web of trust?

I'm studying network and system security and I came across the phrase "web of trust". From Wikipedia: In cryptography, a web of trust is a concept used in PGP, GnuPG, and other OpenPGP-compatible ...
Amanuel Nega's user avatar
10 votes
2 answers
16k views

Which extensions to use for a S/MIME certificate?

Analogously to the SSL server certificate question, which extensions should I use for S/MIME, and should the CA be restricted somehow as well? (I'm using openssl, which at the moment creates CA and ...
Tobias Kienzler's user avatar
16 votes
2 answers
15k views

OpenSSL PKCS#7 vs. S/MIME

OpenSSL 1.0.1c onwards seems to offer CMS support. I have difficulty understanding the difference between smime and pkcs7. S/MIME specs are layered on PKCS#7 (so says Wikipedia). Now in openssl I ...
user907810's user avatar
9 votes
2 answers
1k views

I want trusted SMIME certificates for 3rd parties. Is this a reasonable configuration?

I want to send out SMIME certificates with my emails, and want to deploy the following PKI Root01 (All EKU, All Constrants, No Restrictions) PolicyInt01 (Internal applications, not trusted by 3rd ...
makerofthings7's user avatar
3 votes
2 answers
4k views

Can I buy a signing-valid certificate for internal use?

So now that I have to implement "secure transport" as defined by The Direct Project (not to mention reinventing a bunch of wheels, but that's another story for SO), I find myself staring down the ...
GeminiDomino's user avatar
1 vote
2 answers
2k views

Create CSR for S/MIME certificate from existing OpenPGP key pair

While increasing my communication security as much as possible, I came across OpenPGP & S/MIME and already use an OpenPGP key pair in both of my mail clients (PC & smartphone). I believe the ...
Yoda's user avatar
  • 113
15 votes
2 answers
5k views

Obtaining an S/MIME certificate without disclosing my private key to the TTP

I would like to obtain a trusted S/MIME certificate, but all the certificate authorities I have asked so far generate the keypair on their server, sign the certificate and send me both the private key ...
user1043479's user avatar
9 votes
2 answers
1k views

Apart from the lack of native Outlook support, why should one prefer S/MIME over PGP/MIME for email?

From my (still quite subjective) point of view, GnuPG/PGP is superior to SSL (or more specifically, PGP/MIME over S/MIME; maybe in other areas SSL is the better choice), e.g. due to the support of ...
Tobias Kienzler's user avatar
6 votes
2 answers
10k views

Verify S/MIME signature with no certificate included

Let's sign a file with $ openssl smime -sign -in file -out file.sign -outform DER -inkey private.pem -signer certificate.pem -nocerts With the option -no certs no certificate is included in file....
user1511417's user avatar
3 votes
1 answer
417 views

Does PKCS #7 (CMS) add assurance to an email if a CRL/OCSP response is included, then revoked?

Suppose I issue a signing certificate in January, and have a daily CRL issued (expires in 1 day) to verify the validity of that signature. Then sometime in July I need to revoke that certificate. My ...
makerofthings7's user avatar
3 votes
1 answer
569 views

Are WoSign S/MIME certificates generated on the server side and therefore unsafe to use?

WoSign has been in the media for offering free server and client certificates. Since one of my (free) S/MIME certificate from another CA is about to expire soon after one year and WoSign offers ...
Gurken Papst's user avatar
3 votes
2 answers
13k views

What Enhanced Key Usages are required for PKI infrastructure tasks? (OIDs for OSPF and CRL signing, etc)

I'm building a constrained PKI that specifies EKUs for the the entire hierarchy and want to document the OIDs required for PKI tree maintenance tasks. I understand that clients may not validate the ...
makerofthings7's user avatar
1 vote
1 answer
413 views

What usually happens to the symmetric (session) key after decrypting an email? Can the key be recovered if changing private keys?

I've been preparing for a CISSP exam and was reading about applied cryptography in regard to email. It's my understanding that the popular schemes (PGP,S/Mime) use a combination of asymmetric and ...
jaybeatle's user avatar
1 vote
1 answer
482 views

What exactly is digested in an S/MIME signated-only e-mail?

What exactly is digested in an S/MIME signated-only e-mail? It's definitely not only a sha256-digest of the original message, which means that $ openssl dgst -sha256 <<< "Text" ...
user1511417's user avatar
1 vote
1 answer
520 views

Automatically import/deploy/distribute private key to users for use with S/MIME

it is an Environment with Microsoft Active Directory, Exchange and Windows/Outlook as Client. Now there are the users which have their own private certificates to send signed mails and encrypt ...
Blafasel's user avatar
0 votes
1 answer
705 views

s/mime edit an existing certificate

We are using an encryption appliance that is capable of creating S/MIME certificates for internal users. The appliance is synchronizing with AD to get the user. When the certificate is created it will ...
cyzczy's user avatar
  • 1,588