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1

The RFC for CSRs - https://tools.ietf.org/html/rfc2986 - actually gives a different reason why the CSR is signed. It doesn't say anything about preventing the CSR being modified in transit, but says that it is to prevent someone requesting a certificate for a key that is not theirs (and says this is only a minor issue): " Note 2 - The signature on the ...


1

I think it is fair to consider the message digest to be a random string because it's a hash of something that you don't choose (the person sending you the message chooses it). So you have a random, known plain text (the digest), and it's encrypted version with a private key (the signature). Note that assuming that the signature is authentic, having the ...


2

Does using a public-key encryption algorithm in a digital signature scheme enable any additional types of attack? Yes. Using PKE for a digital signature has additional attacks; e.g., if you are using an RSA signature there are collision attacks on the hash function where if you can construct two messages m and m' that both have the same hash (H(m) = ...


5

It's actually not a SHA1 hash in the CSR. It's a signature of the message. For simplicity, I'll assume we are talking about RSA certificates, where the public key is (N, e) (the modulus and public exponent which is typically 65537) and the private key is (N, d) (the modulus and the private exponent which can be easily calculated via Euclid's extended ...


0

Is this for WS-Fed or for SAML? I've only ever used this for SAML. In the SAML world, this is imported from the partner metadata and is the public key of the certificate the partner uses to sign assertions (In WS-Fed terms = claims). The RP uses this to validate the assertions.


0

Digital code signing certificates that verify you as a trusted source are available from amongst others: StartCom, VeriSign/Symantec, DigiCert, TC TrustCenter, Comodo, GoDaddy, Thwaite and GlobalSign . Typically these are valid for a year, longer costs more. If you do buy one, do not let the signing cert get out of your hands, keep it on one build server in ...


2

You don't issue certificates with an SSL certificate -- you issue certificates with an intermediate CA certificate. That's a different beast; namely, contrary to what is colloquially known as "an SSL certificate", an intermediate CA certificate is granted CA power by virtue of including a Basic Constraints extension with the cA flag set to TRUE. Presence of ...


0

Yes, this would be possible if any CA would sell you such an intermediate CA. But no, they (hopefully) will not do it. The problem is, that the current SSL PKI does not support restrictions for intermediate CAs. This means, once you own such intermediate CA you would be able to issue any certificates you want. This would be certificates for your own ...


0

Don't store the private keys in a file on the disk! Use a secure hardware appliance (network solution) or a smart card (for one-off jobs).


1

Ok here is a good one that is not commonly mentioned as a digital signature security risk. There is a technique called blind signature. Which usually used for anonymous authentication like in anonymous P2P network, electronic voting, digital cash, etc. Now, if the system use the same private key for regular digital signature and for blind digital ...


0

If I'm a pirate, I can intercept Alice message, and use Alice's public key to generate the signature too, no? Basically you can use any random sequence of bits and feed them to the RSA encryption algorithm as a key and it will give you some output. To be meaningful, the encryption and the decryption key must have the mathematical relation that RSA ...


1

There's a bit of confusion. Alice encrypts message with Bob's public key Alice signs the message with her private key (only she has). Bob checks the signature with Alice's public key. Bob is able to decrypt the message with his private key (only he has). In this way, you know that Alice sent the message because only she has her private key. Now if ...


2

Bob does not "generate" the signature with Alice's public key. Signature generation requires the private key. What Bob does is verifying the signature; verification needs only the public key. Indeed, the public key can safely be made public precisely because knowing the public key is not sufficient to generate signatures. (You may have been confused by ...


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Yes, this is exactly what our customers do with CoSign. The CoSign appliance includes a secure CA. Certs are generated/disabled automatically as authorized signers are added/removed to a "signers" group in Active Directory. CoSign signs Word, Excel, and PDF files out of the box. Also XML, Tiff and anything else. Word, Excel, and PDF docs can be signed ...


0

A simple Google search points to this page which explains how to sign Word documents, with Word itself. The signer must own a certificate, and the signature will be considered as valid by any Word instance only if that certificate has been issued by one of the CA that the host Windows system trusts. Most commercial CA can sell certificates which will be ...



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