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0

/as switch to signtool.exe does that: /as - Appends this signature. If no primary signature is present, this signature is made the primary signature. See: https://msdn.microsoft.com/en-us/library/windows/desktop/aa387764(v=vs.85).aspx


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For that first use you're doing unauthenticated DH. And this is only safe against passive eavesdroppers. It is NOT safe against an active Man-in-the-Middle (MITM). So if you were MITM'd during that first exchange, then all bets are off. If that time-window of exploitation is small enough for your purposes, you may still want to use it. (So what you're ...


0

A little bit late... The revocation of certificate (C1) used to create timestamp (T1) does not mean that the timestamp is no longer valid. In fact if the T1 was create before the revocation date of the C1 and the C1 is still not expired or its revocation data is still available (ex: CRL extension expiredCertOnCRL(oid: "2.5.29.60")) then you can still create ...


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What you're asking to do is possible but quite difficult. First of all you need to understand a few ideas so here we go. Firstly, signature schemes. You've no doubt looked at digital signature schemes on the web and you might rightly ask - so why don't you just sign the whole file? Well, the answer to that is that in at least the case of RSA, you open ...


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Do bitcoin miners(or some of them) accept customizable inputs and hash them in bulk(instead of accepting some more high-level instruction and do mining works automatically)? Bitcoin miners generally take a parameter called "target" and "header" and return a nonce+overflow. I don't think it's possible to hash X times, resulting in predictable output ...


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Generally there are two types of Key Generation available as offline and online generation. Offline Generation is like CA will create the key pairs and issue certificate to the other party by means of trustworthy between them as means of generation and issuance. And also in some cases , the endusers or subscribers will not aware of what is CSR and key ...


2

A server can use a self-signed certificate to identify itself. Clients then have to trust this certificate when they connect or use the server's service. In PKI infrastructure you normally don't have the CA generate the key-pair unless its the root certificate. Clients and intermediate CAs will generate their own key-pair and use the CSR to have the ...


0

First, the nonce you get from the web service must be cryptographically secure (unpredictable) and used only one time to avoid replay attacks. Then, there is nothing wrong with this approach, as soon as the web service stores the public key from the client and is able to verify its authenticity. Moreover, one drawback to consider, is signature verification ...


-1

Larry>>SHA1 does not use a key. Signing is done with 2048 bits RSA, SHA1 is just used for Message Digest. If data is less than 2048 bits you get equal strength in the signature without SHA, just pad the data with FF, the strength of the signature is in the key-length not in the Message Digest process. Using SHA1 alone as a signing method is not recommended. ...


3

You claim: digital signatures are used to verify the trustworthiness of information. This is right, at least for some interpretations of "trustworhtiness". Actually, a digital signature can be used to verify that the information has been created by some entity having access to the private key to the public key referenced by that signature, and has not ...


3

To sign something digitally, it is necessary for me to have a private key and for the matching public key to be transmitted to the message recipient over a secure channel that prevents tampering or substitution. I can then easily prove that I originated the message by hashing the message, encrypting the hash using the private key, and attaching the encrypted ...


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Yes, if it is set to be revoked the next week when a new CRL is set to be released, I would wait. Given that you said and put quotations around "probably" in reference to being valid for the remaining week, this would be a red flag to me and again, I would wait the week until next CRL. If access is not absolutely necessary and required for business ...


1

You could encode like this: x1key1y1data1x2key2y2data2 Where x1 is the lenght of the key, and y1 is the lenght of the data. This way you ensure that the keys are in the same order, and you can put any binary data on it. Just define a limit for the key and data lenght, and use padding to make sure x and y uses the same lenght: 004key1005test1002k1025long ...


2

The specific case of a private key being compromised is actually handled already, but you have to do it right in the first place. The correct way to do it is to use a secure timestamp as part of the signature. These timestamps are provided by trusted third party servers (there are several ones that are usable for free provided by big names in the security ...


1

If you want a simple yet secure signature scheme, take a look at Full-Domain-Hash (FDH). Properly randomized padding (as in PSS) can strengthen the scheme against chosen-plaintext attacks. AFAIK the main effect is that it improves the tightness of the security proof a bit, which I consider a relatively small advantage. But since the attacker can choose ...


1

I guess from reading old white papers out there, that only the self signed root CA Certificate is not affected by the SHA-1 deprecation plan and can still use SHA-1, as clients have other means to check for integrity of root certificates. All other certs should be replaced. Here is full description: ...


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B) is in fact the correct answer, at least for the kinds of attack found against MD5 and SHA1. Those hashes are vulnerable to a collision attack, which means an attacker can reasonably find two things that hash to the same value. If he gets the victim to sign one, he can then just use that same signature on the other. However, he can't necessarily find ...



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