Questions tagged [smime]

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

14 questions with no upvoted or accepted answers
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Manually verifying signature in S/MIME mail with openssl

I'm trying to manually verify the signature in an S/MIME signed email with openssl as part of a homework. While I have the mail and can extract the chain of certificates, I'm failing to extract the ...
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175 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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191 views

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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147 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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450 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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393 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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562 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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780 views

Distribute S/MIME public keys and CA cert for email security

I have my own CA. I want to distribute S/MIME certificates for 10 different users. I saw S/MIME keyservers from http://wiki.cacert.org/KeyServers, but I don't want to use public servers. What is the ...
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1answer
254 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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1answer
105 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 ...
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32 views

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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2k views

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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42 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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55 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?