network profile
| bio | website | |
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| location | ||
| age | ||
| visits | member for | 6 months |
| seen | Jun 12 at 21:12 | |
| stats | profile views | 0 |
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Jun 4 |
awarded | Scholar |
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Jun 4 |
comment |
Encrypt-then-MAC paradigm Great answer that is really helpful to me. Thank you. Is there a mode of operation for AES you can recommend? |
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Jun 4 |
accepted | Encrypt-then-MAC paradigm |
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Jun 4 |
comment |
Encrypt-then-MAC paradigm I know that HMAC itself is based on twice the application of a hash function, thus you might wonder, why I asked question 1. My reasoning is when I have something like HMAC(some || concatenaed || fields || ciphertext), it might be possible for an attacker to shift the boundary between "fields" and the ciphertext, because ciphertexts usually don't have a fixed length. |
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Jun 4 |
awarded | Supporter |
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Jun 4 |
asked | Encrypt-then-MAC paradigm |
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Dec 21 |
comment |
Efficient Symmetric Mutual Entity Authentication Protocol I just used the word "server" to make clear that it's the verifier that receives the authentication token and grants/denies access. I cannot rely on the availability of a cryptographically secure time on the verifier's system nor can I presume both the client and the verifier have a reliable online connection to synchronize their clocks. Also I want to point out that with my scheme the authentication token changes for every new access attempt. Isn't there another light-weight protocol for access control that isn't based on timestamps but offers strong mutual entity authentication? |
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Dec 21 |
comment |
Efficient Symmetric Mutual Entity Authentication Protocol I cannot use Kerberos since I don't have synchronized clocks. Also a dedicated Kerberos server is not an option and Kerberos not really that efficient. @PaŭloEbermann: Let's say you'd use a smartcard as hotel room key where $X$ is the smartcard and $S$ the door of your room. As soon as $X$ has authenticated to $S$, access is granted and the door is opened. Now under the condition that the door is offline I also want to track which door has been opened by that particular smartcard key - i.e. to collect all access (attempts) in a dedicated database. |
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Dec 20 |
awarded | Student |
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Dec 20 |
comment |
Efficient Symmetric Mutual Entity Authentication Protocol Thanks for your answer @PaŭloEbermann. If $X$ wanted to have access to server $S$, $X$ would need to provide $S$ a cryptographic evidence about his claimed identity so that $S$ knows whether to grant access or not. But I also want to have that the server $S$ proves his identity to $X$ so that the client itself knows it is accessing the right resource. I don't need to exchange any further information after access has been granted - thus I don't need to agree upon a symmetric encryption key which is used for efficient message encryption. But I want it to be as secure and efficient as possible. |
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Dec 20 |
awarded | Editor |
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Dec 20 |
revised |
Efficient Symmetric Mutual Entity Authentication Protocol added 19 characters in body |
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Dec 20 |
asked | Efficient Symmetric Mutual Entity Authentication Protocol |
