Questions tagged [smime]

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

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5answers
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What actions should I, as an end user, take in response to EFAIL?

There's a lot of talk about EFAIL: The EFAIL attacks exploit vulnerabilities in the OpenPGP and S/MIME standards to reveal the plaintext of encrypted emails. In a nutshell, EFAIL abuses active ...
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4answers
2k 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 ...
19
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3answers
483 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 ...
12
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2answers
10k 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 ...
12
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2answers
4k 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 ...
9
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2answers
20k 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 ...
9
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1answer
11k 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 ...
9
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2answers
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 ...
8
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2answers
846 views

Why don't banks sign their email using S/MIME?

If email sent by my bank included S/MIME signatures that my mail client can verify, then I would have the assurance that the mail was not tampered with or sent by some malicious third-party. Most ...
8
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1answer
186 views

S/MIME certificates and “information leakage”

I'm considering getting an S/MIME certificate that verifies my name and email address. I've been trying to ascertain what information "leaks" if I do. The Wikipedia page on S/MIME says: Depending ...
7
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1answer
661 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 ...
7
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1answer
6k views

Parsing a PKCS7 detached signature hash

I'm trying to manually verify signatures of Apple iOS Passbook files, which are PKCS #7 detached signatures of the RSA key of the Apple developer who created the file. Which means there's a file "...
7
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3answers
2k 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 ...
7
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1answer
1k 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 ...
6
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1answer
677 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 ...
6
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3answers
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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 ...
6
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1answer
8k 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 ...
6
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1answer
4k views

What are the security differences between SMIME email and PGP email? [closed]

Outside of key distribution, and specific to the technical details relating to encrypted email data (message body), what's the difference between SMIME and PGP? Example comparisons Security ...
5
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2answers
327 views

Is it possible and does it make sense to sign an E-mail with PGP and S/MIME?

After some research without any answer to my question, if it's possible and does it make sense to sign an E-mail with PGP and s/mime (?), I'm hoping to get an answer here. I know that, PGP and S/MIME ...
5
votes
1answer
2k 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 ...
5
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1answer
958 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 ...
5
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2answers
388 views

What encryption and signature systems (don't?) allow for plausible deniability of the OP's key being used?

I need to prevent Mallory from blindly matching encryption and signing keys to messages Hypothetical scenario: A user creates a public key An encrypted or signed payload exists. With only public ...
4
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1answer
2k views

S/MIME signing and verification - how do I find proper certificate?

I'm trying to debug a S/MIME signing framework that is functioning wrong. On the input I have a signed message with detached certificate a certificate which private key the message was probably ...
4
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2answers
1k views

EU standardized digital signature for form-data

Problem I am trying to identify if there are any standards (accepted by the EU) regarding client-side digitally signing the form-data before it is submitted. So the constraints are: know standard ...
4
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1answer
159 views

Certificate and Path validation for S/MIME

I am working on a S/MIME client development and was wondering if there is a list of certificate and path validation checks that a client needs to perform while validating an email signature. My ...
3
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2answers
3k views

S/MIME certificate expired and renewed, do my correspondents have to do anything?

My PKI certificate (Digital ID for email from Symantec, issuer is "VeriSign Client External Certification Authority - G3") expired after 1 year and so I have renewed it. Do the people I correspond ...
3
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1answer
10k 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 ...
3
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2answers
3k 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....
3
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3answers
173 views

What's the point of S/MIME?

I received an email recently which displayed as an empty body with a smime.p7m attachment. After some Googling, I discovered it was an encrypted email -- neat! So I started looking for the key. But... ...
3
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1answer
219 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 ...
3
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2answers
510 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 ...
3
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1answer
4k views

Receiving S/MIME signed emails with Gmail

When I receive an email signed (not encrypted) with S/MIME in my Gmail account, it provides me no option of verifying the signature when I'm using the webmail interface. Which is fine, I have made ...
3
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2answers
2k 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 ...
3
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2answers
10k views

Decrypting .P7M File with Key (.pem) using OpenSSL

My knownledge about security is limited so I need some help here. The Question I want to Decrypt a .P7M file using its private key (.pem). I would prefer to use OpenSSL for this. Tried so far ...
3
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1answer
479 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 ...
2
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4answers
204 views

Is PGP or S/MIME useful when both servers are self-controlled?

With regards to encryption and preventing a 3rd party from viewing my emails (and ignoring validity/signing), is encrypting an email via PGP or S/MIME useful when I control my server and my recipient ...
2
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1answer
917 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 ...
2
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2answers
103 views

smime - is encrypting reply to a signed mail without own cerificate possible?

From what I understood, was that having a S/MIME certificate allow me to sign emails, and any recipient of my signed email would be able to encrypt emails send to me. Is that correct? or does the ...
2
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1answer
1k views

Yubikey with S/MIME certificate

I would like to do the following. Can anyone tell me if this is possible? Store the private key for an S/MIME certificate from Digicert on a Yubikey. Backup the private key to another location. Use ...
2
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1answer
174 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/ https://keyserver.pgp.com/...
2
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2answers
54 views

Encrypted email from outlook to other

I have recently setup S/MIME in Outlook for my company's employees to send encrypted and digitally signed emails to one another. Is it possible to send encrypted emails to other email platforms from ...
2
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0answers
112 views

Certificate Transparency and S/MIME certificates

When people speak about CT that usually means only TLS certificates are stored in log. However, CT probable might be considered for usage in other PKI-based technologies. Is CT designed to log S/MIME ...
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1answer
79 views

Signing but not encrypting trivial generic e-mails

Let's assume my professor sends a signed but unencrypted (S/MIME) e-mail to us students like this: Dear students, there will be no class tomorrow. I'm sick. Regards Professor Now I ...
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1answer
1k 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 ...
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2answers
218 views

Can I re-sign SMIME certificates with my own CA?

Many large corporations choose to use their own CA to sign their employee's SMIME certificates. Which is fine for internal use, but they typically expect external users to import their corporate CA ...
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1answer
2k views

Is RC2-CBC at all secure?

(And more generally, is there a site listing which various algorithms are still considered secure, so I wouldn't have to ask that here? Wikipedia's "known best attack" is not particularly clear.) I ...
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3answers
449 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, ...
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1answer
3k 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 ...
1
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2answers
1k 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 ...
1
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1answer
71 views

What should be OpenSSL .cnf file equivalent of certreq .inf for S/MIME?

Currently I'm using certreq to prepare CSRs for S/MIME certificates. I want to move away from it and start using OpenSSL for key/CSR generation. My .inf file looks like this: [Version] Signature="$...