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3
votes
1answer
144 views

Why shouldn't I sign my email newsletter using an s/mime email certificate?

I currently offer email subscriptions on my blog, something I coded myself in PHP. People sign up on the blog using their email address. I send them an email with a link to verify their email address ...
1
vote
3answers
66 views

Simplifying SMIME by re-using the Public & Private key across email accounts

I need to simplify (at the cost of security features) an SMIME deployment. How can I generate a CSR that reuses the same public and private key for more than one email address? In other words, I ...
2
votes
2answers
135 views

Does SMIME differ from TLS, PGP, DMARC signature, or a Portal Encrypted email message in terms of legal non-repudiation?

I'm interested in protecting email messages from NSA-style snooping, but don't want to incur additional legal risk in doing so. In other words, does SMIME encryption and/or signing cause a given ...
0
votes
0answers
18 views

Should an SMIME signing and encryption key have different expiration dates?

Assuming the client supports different keys, what is some rationale that should be considered for signing and encryption keys? For example, since the encryption key needs to be present on each device ...
1
vote
3answers
98 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 ...
1
vote
1answer
139 views

How are private keys (sMIME, PGP, etc) synchronized across a user's devices?

Given that user needs to store a copy of the same private key on each of his devices (in order to decrypt email and other data encrypted with the public key) ... what are some general techniques for ...
1
vote
1answer
62 views

When does S/MIME require the other party's certificate and when is their key enough?

Trying to understand S/MIME implementation, I see that sometimes you must have the other party's certificate, and sometimes its enough to just have their public key. I'm confused as to when you need ...
6
votes
1answer
120 views

Reading older mails signed with a certificate that has meanwhile expired

A few years ago I have used S/MIME certs to sign (and encrypt) my mails. The reason for which I stopped signing was the following: My (class 2) cert was issued on Jan. 1st 2008 (just a sample). It ...
2
votes
2answers
185 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 ...
1
vote
3answers
188 views

S/MIME doesn't protect against a stolen password, right?

We're setting up S/MIME so that we can send encrypted emails. However, I have a bit of a stupid (and maybe obvious) question... If someone steals a password for either the sender or the receiver, ...
-2
votes
2answers
183 views

What was the Lavabit's backdoors to their customers' e-mails? [closed]

There has been some talk about the Lavabit's case. New info was published today, but not important. I'd like to know how Lavabit worked. First I thought they just did something with OpenPGP. Then I ...
4
votes
2answers
4k views

SMIME email decryption key with OpenSSL

I'd like to know if it's possible to use openssl command to retrieve and decrypt the key for encrypting/decryptig email content. I know I can decrypt the whole encrypted mail by something like this ...
1
vote
1answer
228 views

Detecting SMIME type using OpenSSL CMS

Is it possible to detect S/MIME content types (enveloped or signed) using OpenSSL CMS API? I would prefer to avoid pre-parsing S/MIME headers and let OpenSSL to detect whether message is signed or ...
0
votes
1answer
263 views

How do I determine S/MIME encryption used?

From what I understand it seems that S/MIME uses PKCS #7 which can handle various different types of encryption. How is the choice of encryption method made by the e-mail client and how do I know what ...
0
votes
1answer
133 views

How to fetch and update all my friend's keys? [closed]

Where can I upload a list of my friends and get a list of their keys found on keyservers? Here are some key servers: http://keyserver.ubuntu.com:11371/ http://pgp.mit.edu/ ...
2
votes
1answer
1k views

How do I share my S/MIME public key?

I have setup S/MIME encryption for my email address, and I'd like to allow people to download the public key from my website, rather than having to first receive an email from me. I want the public ...
2
votes
2answers
2k 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 ...
3
votes
1answer
574 views

What's a trustworthy S/MIME Certificate Provider that generates my private key in my browser?

I read this question on the process of generating a private S/Mime key. I looked at Comodo - which offer free e-mail certificates. I'm trying to find out whether Comodo generates the private ...
1
vote
1answer
76 views

Bootstrapping dual SMIME certificates for signing and encryption?

To maintain the non-repudiation property of signing while still having escrow for the encryption key, it's recommended to have a separate certificates (and pub-priv keys) for signing (say CertSign) ...
15
votes
3answers
379 views

What expectation of privacy is there with US-based vendors with the LavaBit and SilentCircle shutdown?

Lavabit hosts a secure messaging service that was recently shut down. Likewise SilentCircle has preemptively done the same thing with their email-based service. It seems that the justification for ...
2
votes
1answer
282 views

Why should I pay for an email S/MIME certificate?

There are quite a few SSL certificate companies out there that offer free email S/MIME certificates. There are also paid versions as well. I need about 6 email certificates for some company email ...
15
votes
3answers
780 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 ...
3
votes
3answers
644 views

Where to get/buy a CSR generated S/MIME certificate

I'm not sure if the question is eligable for this board as I ask for concrete service providers which can be kind of advertisement, but there is also technical issue involved, so I give it a try. My ...
8
votes
2answers
2k 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 ...
1
vote
2answers
133 views

Why is S/MIME (instead of PGP) recommended for such an scenario?

A large MNC with approximately 50,000 employees, and with offices in Asia, Europe and North America. This MNC operates its own PKI environment, with a self-signed Certificate Authority based at its ...
1
vote
1answer
1k views

Can I use any ssl certificate to sign and encrypt AS2 message?

I'm absolutely new to this topic of ssl certificates, so please be patient with me. My task is to install an AS2 communication with some business partner. Therefore we need message signing and ...
1
vote
1answer
197 views

How to have Thunderbird include a root certificate?

An eMail signed via S/MIME also contains the X.509 certificate chain containing the public key in order to directly verify the signature (assuming its issuing CA is deemed trustworthy). The chain does ...
1
vote
1answer
371 views

PKCS#7 message constructed by our code, any weaknesses in the output?

We have this as the PKCS#7 encrypted message. We would like to open this up for review and analysis here, for people to poke holes. This sample is generated via test certificates and keys. The concern ...
0
votes
1answer
283 views

Does S/MIME provide means to propagate a certificate's revocation?

Can a revocation certificate for an old X.509 certificate be attached to an email in addition to a replacement certificate in such a way that the client user does not have to manually intervene? Or ...
4
votes
1answer
286 views

Apart from the lack of native Oultook 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 ...
4
votes
1answer
2k 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 ...
2
votes
1answer
1k 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 ...
1
vote
2answers
315 views

S/MIME verification

I am getting emails with smime.p7s attachments. when I look at my mail on my Linux box, I can see base64 encoded block in mail body. I can extract that block and open it on Windows using certmgr and ...