Questions tagged [smime]

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

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Force specific encryption cipher for S/MIME mails

I have a number of contacts who can only decrypt 3DES, when it comes to S/MIME encrypted mails. I'm aware that this is by far not ideal, but better than no encryption at all. My problem is, that I ...
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Email signature with PKCS11?

While S/MIME has been a PKCS7 standard, what happens while I sign/encrypt an email using a smart card implementing PKCS11? Is PKCS7 supported as kind of backward compatibility?
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Why do I need an own certificate to encrypt a S/MIME message?

I try to use Thunderbird to encrypt a message. I do not want to sign the message. Encryption is done with the public key of the receiver. I have imported the certificate of the receiver. But when I ...
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Does SMIME 4, or any prior version, support multiple private keys for a single individual?

I am investigating S/MIME and if it's possible to have a device-specific signing key (or if that's a good idea). The intention is to reduce risk by making the private key read only on the device(es) ...
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1answer
275 views

Why do we need DKIM to be used along with S/Mime?

S/Mime can be used to encrypt email and it can also be used by the sender to provide his digital signature so that the recipient is able to confirm the authenticity of the sender. Why then do we ...
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Is it possible to decrypt Outlook Web App S/MIME messages in a web browser with same webclient? [closed]

Normally, you would use a mail client for mail encryption. Though, I can access smartcard security functions from the browser for a secure login. Therefore, is it possible to decrypt Outlook Web App ...
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3answers
301 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... ...
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117 views

Get S/MIME from Digicert, store in escrow on on-prem CA

I'm trying to crack the following nut: I have a contract with Digicert for S/MIME certificates for my org. Digicert allows to use their API for cert issuance. Unfortunately I can't let users self-...
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1answer
117 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="$...
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326 views

Digital Signature is not valid

I recently received a digital signed email from a friend and the certificate is issued by COMODO RSA Client Authentication and Secure Email. My problem is the thunderbird detect it as a "Not Valid ...
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237 views

Replying to a digitally signed email using thunderbird

So Basically I sent a digitally signed email using a certificate issued by Sectigo RSA Client Authentication and Secure Email CA. Now the recipient of the email replied to me with a certificate ...
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2answers
75 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 ...
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2answers
290 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 ...
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1answer
172 views

unable to verify AWS EC2 Instance Identity Document with libressl

I'm trying to follow the steps here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html to verify an instance identity document, and I'm getting success when I ...
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1answer
64 views

Public Key Crypto - sign Bob's name into Alice's message or encrypt Alice's name

I was reading Defective Sign & Encrypt in S/MIME,  PKCS#7, MOSS, PEM, PGP, and XML and in section 5.1  Naming Repairs By signing Bob's name into her message, Alice explicitly identifies him ...
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1answer
93 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 ...
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What is the solution to digitally sign email apart from S/MIME and GPG/OpenPGP [closed]

I have tried to implement S/MIME, however, I've found out that S/MIME seems to be obsolete, in my perspective. Since S/MIME cannot operate on Google Chrome or Edge. Another solution I found is ...
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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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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 ...
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0answers
384 views

Use of S/MIME capabilities attribute

If you examine an S/MIME-signed file with $ openssl cms -in file.sgn -noout -cmsout -print you see that S/MIME capabilities are also included in the signature: ... object: S/MIME Capabilities (1.2....
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0answers
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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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2answers
4k 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....
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1answer
163 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" would ...
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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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2answers
279 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
196 views

Is gnupg's tsign compatible with S/MIME

GnuPG supports creating trust signatures using the tsign sub-command. (The documentation is not really verbose about this.) By using this option it is possible to create a certificate hierarchy ...
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Using a PowerShell Self-Signed Certificate for Outlook S/MIME

I'm testing out a way that myself and a few others could use S/MIME for our email traffic. I'm using Outlook 2016 with Win10. I have generated my test certificate with the following command in ...
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1answer
369 views

Disable 3DES (Triple DES) in thunderbird

Thunderbird still uses 3DES for SMIME encryption (bug #1167857). Since 3DES is severely "broken" and uses only 80 bits of security, I would like to tell my Thunderbird, not to use that algorythm any ...
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1answer
5k 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 ...
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41 views

hashing algorithm mail signing

What determines the hashing algorithm used form mail signing? I sign an mail. it is first run through a hashing algorithm and next encrypted with my private key. Bob, the receiver will decrypt it with ...
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1answer
39 views

Is my SMIME certificate secure?

Lets take a random well-known Root CA. This CA allows me to sign my own certificate so that it is immediately trusted by others since they trust the root CA. The only thing, which the CA ever sees is ...
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2answers
2k 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 ...
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1answer
6k views

Incoming email with smime.p7s attachment

This is a scenario I have at work. We're receiving emails with .p7s attached files from a single user of a company(hence the company domain for eg. abc.com) our users interact with via mail. We use ...
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51 views

What public key systems allow for delegation?

I am looking for a public key system that allows for a 3rd party to use that key for other purposes. What private key systems allow for this? PGP, S/MIME, PKI?
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1answer
224 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 ...
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2answers
887 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 ...
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1answer
2k 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 ...
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1answer
191 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 ...
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1answer
190 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 ...
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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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2answers
1k views

Are these statements correct [closed]

Are the following three statements more or less correct: -To send someone an encrypted email basically entails having access to their public key (either smime or pgp). Thus for all practical ...
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2answers
11k 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 ...
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1answer
482 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 ...
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2answers
336 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 ...
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4answers
234 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 ...
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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 ...
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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 ...
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0answers
437 views

How should an ISP approach Mutual Auth TLS for SMTP email? (Domain Auth Email)

I'm looking for an easy to deploy way to make email clients (MUAs) display my email messages in a secure manner. PGP and SMIME both do this today, but they are high touch, and require software or ...
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1answer
230 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 ...
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2answers
395 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 ...