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• How do I Duplicate a MSSQL Symmetric Key

  - by rlb.usa

  We have a server with a database that has a symmetric key (Database - Security - Symmetric Key). We have a backup duplicate databases that we are using as a test databases, but we don't have this key in there. How can I duplicate this symmetric key and put it in the existing databases? It has to have the same value and key-name as the other one. This is on MS SQL Server 2008 .

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• How can I Duplicate a MSSQL Symmetric Key?

  - by rlb.usa

  We have a server with a database that has a symmetric key (Database - Security - Symmetric Key). We have a backup duplicate databases that we are using as a test databases, but we don't have this key in there. How can I duplicate this symmetric key (or make a new one exactly like the old) and put it in the existing databases? It has to have the same value and key-name as the other one. This is on MS SQL Server (edit) 2008 .

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• Symmetric Encryption

  Cryptography is an increasing requirement for applications, so it is great that it is part of the .NET framework. Matteo builds on his first article that explained Asymmetric Cryptography and Digital Signatures, and tackles Symmetric Encryption and how to implement it in the .NET Framework.

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• How can I duplicate a SQL Server symmetric key?

  - by rlb.usa

  We have a server with a database that has a symmetric key (Database - Security - Symmetric Key). We have a backup duplicate databases that we are using as a test databases, but we don't have this key in there. How can I duplicate this symmetric key (or make a new one exactly like the old) and put it in the existing databases? It has to have the same value and key-name as the other one. This is on SQL Server 2008.

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• Symmetric ds issue

  - by gaurav

  Hi , I am using postgresql8.3 and include symmetris ds 1.5.1 in my application.But the replication is done fine for client to server . but the replication is not done from server to client. I am newer to use the symmetric ds .Can anyone plese let me know the checklist of using symmetric ds for cheching that my symmetric ds is well configure or not. Thank You very Much

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• Is frozenset adequate for caching of symmetric input data in a python dict?

  - by Debilski

  The title more or less says it all: I have a function which takes symmetric input in two arguments, e.g. something like def f(a1, a2): return heavy_stuff(abs(a1 - a2)) Now, I want to introduce some caching method. Would it be correct / pythonic / reasonably efficient to do something like this: cache = {} def g(a1, a2): return cache.setdefault(frozenset((tuple(a1), tuple(a2))), f(a1, a2)) Or would there be some better way?

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• Numpy ‘smart’ symmetric matrix

  - by Debilski

  Is there a smart and space-efficient symmetric matrix in numpy which automatically fills [j][i] when [i][j] is written to? a = numpy.symmetric((3, 3)) a[0][1] = 1 print a # [[0 1 0], [1 0 0], [0 0 0]] An automatic Hermitian would also be nice, although I won’t need that at the time of writing.

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• Is Md5 Encryption Symmetric or Asymmetric?

  - by PF1

  For my iPhone application, Apple wants to know if my password encryption (md5) is greater then 64-bit symmetric or greater then 1024-bit symmetric. I have not been able to find it online, so I am wondering if anyone knows the answer. In addition, is this considered an appropriate encryption technology for passwords, or should I use something different? Thanks for any help!

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• gpg symmetric encryption using pipes

  - by Thomas

  I'm trying to generate keys to lock my drive (using DM-Crypt with LUKS) by pulling data from /dev/random and then encrypting that using GPG. In the guide I'm using, it suggests using the following command: dd if=/dev/random count=1 | gpg --symmetric -a >./[drive]_key.gpg If you do it without a pipe, and feed it a file, it will pop up an (n?)curses prompt for you to type in a password. However when I pipe in the data, it repeats the following message four times and sits there frozen: pinentry-curses: no LC_CTYPE known assuming UTF-8 It also says can't connect to '/root/.gnupg/S.gpg-agent': File or directory doesn't exist, however I am assuming that this doesn't have anything to do with it, since it shows up even when the input is from a file. So I guess my question boils down to this: is there a way to force gpg to accept the passphrase from the command line, or in some other way get this to work, or will I have to write the data from /dev/random to a temporary file, and then encrypt that file? (Which as far as I know should be alright due to the fact that I'm doing this on the LiveCD and haven't yet created the swap, so there should be no way for it to be written to disk.)

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• Safe non-tamperable URL component in Perl using symmetric encryption?

  - by Randal Schwartz

  OK, I'm probably just having a bad Monday, but I have the following need and I'm seeing lots of partial solutions but I'm sure I'm not the first person to need this, so I'm wondering if I'm missing the obvious. $client has 50 to 500 bytes worth of binary data that must be inserted into the middle of a URL and roundtrip to their customer's browser. Since it's part of the URL, we're up against the 1K "theoretical" limit of a GET URL. Also, $client doesn't want their customer decoding the data, or tampering with it without detection. $client would also prefer not to store anything server-side, so this must be completely standalone. Must be Perl code, and fast, in both encoding and decoding. I think the last step can be base64. But what are the steps for encryption and hashing that make the most sense?

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• MVC 2 AntiForgeryToken - Why symmetric encryption + IPrinciple?

  - by Brad R

  We recently updated our solution to MVC 2, and this has updated the way that the AntiForgeryToken works. Unfortunately this does not fit with our AJAX framework any more. The problem is that MVC 2 now uses symmetric encryption to encode some properties about the user, including the user's Name property (from IPrincipal). We are able to securely register a new user using AJAX, after which subsequent AJAX calls will be invalid as the anti forgery token will change when the user has been granted a new principal. There are also other cases when this may happen, such as a user updating their name etc. My main question is why does MVC 2 even bother using symmetric encryption? Any then why does it care about the user name property on the principal? If my understanding is correct then any random shared secret will do. The basic principle is that the user will be sent a cookie with some specific data (HttpOnly!). This cookie is then required to match a form variable sent back with each request that may have side effects (POST's usually). Since this is only meant to protect from cross site attacks it is easy to craft up a response that would easily pass the test, but only if you had full access to the cookie. Since a cross site attacker is not going to have access to your user cookies you are protected. By using symmetric encryption, what is the advantage in checking the contents of the cookie? That is, if I already have sent an HttpOnly cookie the attacker cannot override it (unless a browser has a major security issue), so why do I then need to check it again? After having a think about it it appears to be one of those 'added layer of security' cases - but if your first line of defence has fallen (HttpOnly) then the attacker is going to get past the second layer anyway as they have full access to the users cookie collection, and could just impersonate them directly, instead of using an indirect XSS/CSRF attack. Of course I could be missing a major issue, but I haven't found it yet. If there are some obvious or subtle issues at play here then I would like to be aware of them.

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• Symmetric Encryption: Performance Questions

  - by cam

  Does the performance of a symmetric encryption algorithm depend on the amount of data being encrypted? Suppose I have about 1000 bytes I need to send over the network rapidly, is it better to encrypt 50 bytes of data 20 times, or 1000 bytes at once? Which will be faster? Does it depend on the algorithm used? If so, what's the highest performing, most secure algorithm for amounts of data under 512 bytes?

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• calculate intersection between two segments in a symmetric way

  - by Elazar Leibovich

  When using the usual formulas to calculate intersection between two 2D segments, ie here, if you round the result to an integer, you get non-symmetric results. That is, sometimes, due to rounding errors, I get that intersection(A,B)!=intersection(B,A). The best solution is to keep working with floats, and compare the results up to a certain precision. However, I must round the results to integers after calculating the intersection, I cannot keep working with floats. My best solution so far was to use some full order on the segments in the plane, and have intersection to always compare the smaller segment to the larger segment. Is there a better method? Am I missing something?

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• Symmetric drawing of a Graph

  - by xxxxxxx

  is there any known algorithm(or package with the algorithm already implemented) to draw a graph in a way that it has symmetry ? for example most of these show symmetry. but putting the nodes evenly distributed on a circle isn't the best way to symmetry is exposed.

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• Diffie-Hellman in Silverlight

  - by cmaduro

  I am trying to devise a security scheme for encrypting the application level data between a silverlight client, and a php webservice that I created. Since I am dealing with a public website the information I am pulling from the service is public, but the information I'm submitting to the webservice is not public. There is also a back end to the website for administration, so naturally all application data being pushed and pulled from the webservice to the silverlight administration back end must also be encrypted. Silverlight does not support asymmetric encryption, which would work for the public website. Symmetric encryption would only work on the back end because users do not log in to the public website, so no password based keys could be derived. Still symmetric encryption would be great, but I cannot securely save the private key in the silverlight client. Because it would either have to be hardcoded or read from some kind of config file. None of that is considered secure. So... plan B. My final alternative would be then to implement the Diffie-Hellman algorithm, which supports symmetric encryption by means of key agreement. However Diffie-Hellman is vulnerable to man-in-the-middle attacks. In other words, there is no guarantee that either side is sure of each others identity, making it possible for communication to be intercepted and altered without the receiving party knowing about it. It is thus recommended to use a private shared key to encrypt the key agreement handshaking, so that the identity of either party is confirmed. This brings me back to my initial problem that resulted in me needing to use Diffie-Hellman, how can I use a private key in a silverlight client without hardcoding it either in the code or an xml file. I'm all out of love on this one... is there any answer to this?

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• Encryption By Certificate

  - by user1817240

  I am encrypting customer name in database at database level. While saving in database only first letter of customer name is saved and hence while decrypting only first letter is retrieved. The following code shows the test sp. ALTER PROCEDURE [dbo].[spc_test_insert] ( @sFIRST_NAME typ_encryptedtext, ) AS BEGIN DECLARE @sSENCRYPTION_KEY char(15) DECLARE @sCERTIFICATE char(22) SET @sSENCRYPTION_KEY='SymmetricKey1' SET @sCERTIFICATE='CustomerCertificate' OPEN SYMMETRIC KEY SymmetricKey1 DECRYPTION BY CERTIFICATE CustomerCertificate; INSERT INTO test_table ( FIRST_NAME, ) Values ( -- Add the Params to be Added... EncryptByKey(Key_GUID(@sSENCRYPTION_KEY),@sFIRST_NAME), ) CLOSE SYMMETRIC KEY SymmetricKey1 END encryption decryption working fine in normal insert but its not working in stored procedure.

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• How to balance a non-symmetric "extension" based game?

  - by Klaim

  Most strategy games have fixed units and possible behaviours. However, think of a game like Magic The Gathering : each card is a set of rules. Regularly, new sets of card types are created. I remember that the firsts editions of the game have been said to be prohibited in official tournaments because the cards were often too powerful. Later extensions of the game provided more subtle effects/rules in cards and they managed to balance the game apparently effectively, even if there is thousands of different cards possible. I'm working on a strategy game that is a bit in the same position : every units are provided by extensions and the game is thought to be extended for some years, at least. The effects variety of the units are very large even with some basic design limitations set to be sure it's manageable. Each player choose a set of units to play with (defining their global strategy) before playing (like chooseing a themed deck of Magic cards). As it's a strategy game (you can think of Magic as a strategy game too in some POV), it's essentially skirmish based so the game have to be fair, even if the players don't choose the same units before starting to play. So, how do you proceed to balance this type of non-symmetric (strategy) game when you know it will always be extended? For the moment, I'm trying to apply those rules but I'm not sure it's right because I don't have enough design experience to know : each unit would provide one unique effect; each unit should have an opposite unit that have an opposite effect that would cancel each others; some limitations based on the gameplay; try to get a lot of beta tests before each extension release? Looks like I'm in the most complex case?

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• Securely Storing Optional Entropy While Using DPAPI

  - by Changeling

  So I am trying to store the symmetric key using DPAPI. All is well and great, but what to do with the entropy? This answered question here really doesn't provide enough insight. It seems like a slippery slope - I could use the machine store to store the entropy but then what prevents someone from getting at that as well? Note: I am storing the current key using the User Scope. So my question is - what is the best way to store the entropy using DPAPI?

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• Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

  - by TX_

  Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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• Is there graceful degradation in symmetric multi-processing (SMP) systems?

  - by Avon

  Since graceful degradation is a fault-tolerant feature, is it true that in a multi-processor systems with symmetric multi-processing, there will be no graceful degradation? Update: http://en.wikipedia.org/wiki/Fault-tolerant_system

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• BAD_UID error while exporting key in CryptoAPI

  - by mindthief

  Hi all, I am writing a test application for Microsoft CryptoAPI. I want to export the secret key of one party using the public key of the second party, and then import that secret key as the second party's secret key (this sets up a shared secret key for communication). Here is my code: if(!CryptExportKey(encryptT->hSymKey, decryptT->hPubKey, SIMPLEBLOB, 0, keyExBuf, &bufLen)) { FormattedDebugPrint(NULL, GetLastError(), "could not export secret key", TRUE); return -1; } if(!CryptImportKey(decryptT->hCryptProv, keyExBuf, bufLen, decryptT->hPubKey, 0, &(decryptT->hSymKey))) { FormattedDebugPrint(NULL, GetLastError(), "could not import secret key", TRUE); return -1; } And this gives the error: 80090001: Bad UID. The public keypair is being generated for both encryptT and decryptT (sender, receiver) by calling: CryptGenKey(encryptT->hCryptProv, CALG_RSA_KEYX, CRYPT_EXPORTABLE, &(encryptT->hPubKey)) Any idea what could be causing the error? Thanks,

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• Can I encrypt value in C# and use that with SQL Server 2005 symmetric encryption?

  - by Robert Byrne

  To be more specific, if I create a symmetric key with a specific KEY_SOURCE and ALGORITHM (as described here), is there any way that I can set up the same key and algorithm in C# so that I can encrypt data in code, but have that data decrypted by the symmetric key in Sql Server? From the research I've done so far, it seems that the IDENTITY_VALUE for the key is also baked into the cypher text, making things even more complex. I'm thinking about just trying all the various ways I can think of, ie hashing the KEY_SOURCE using different hash algorithms for a key and trying different ways of encrypting the plain text until I get something that works. Or is that just futile? Has anyone else done this, any pointers? UPDATE Just to clarify, I want to use NHibernate on the client side, but theres a bunch of stored procedures on the database side that still perform decryption.

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• Algorithm for finding symmetries of a tree

  - by Paxinum

  I have n sectors, enumerated 0 to n-1 counterclockwise. The boundaries between these sectors are infinite branches (n of them). The sectors live in the complex plane, and for n even, sector 0 and n/2 are bisected by the real axis, and the sectors are evenly spaced. These branches meet at certain points, called junctions. Each junction is adjacent to a subset of the sectors (at least 3 of them). Specifying the junctions, (in pre-fix order, lets say, starting from junction adjacent to sector 0 and 1), and the distance between the junctions, uniquely describes the tree. Now, given such a representation, how can I see if it is symmetric wrt the real axis? For example, n=6, the tree (0,1,5)(1,2,4,5)(2,3,4) have three junctions on the real line, so it is symmetric wrt the real axis. If the distances between (015) and (1245) is equal to distance from (1245) to (234), this is also symmetric wrt the imaginary axis. The tree (0,1,5)(1,2,5)(2,4,5)(2,3,4) have 4 junctions, and this is never symmetric wrt either imaginary or real axis, but it has 180 degrees rotation symmetry if the distance between the first two and the last two junctions in the representation are equal. Edit: This is actually for my research. I have posted the question at mathoverflow as well, but my days in competition programming tells me that this is more like an IOI task. Code in mathematica would be excellent, but java, python, or any other language readable by a human suffices. Here are some examples (pretend the double edges are single and we have a tree) http://www2.math.su.se/~per/files.php?file=contr_ex_1.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_2.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_5.pdf Example 1 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,3). Example 2 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,1). Example 5 is described as (0,1,4,5)(1,2,3,4) with distances (2). So, given the description/representation, I want to find some algorithm to decide if it is symmetric wrt real, imaginary, and rotation 180 degrees. The last example have 180 degree symmetry. (These symmetries corresponds to special kinds of potential in the Schroedinger equation, which has nice properties in quantum mechanics.)

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• How does an NTP host switch among the various modes?

  - by James A. Rosen

  The NTPv3 RFC describes five operating modes: Symmetric Active (1): A host operating in this mode sends periodic messages regardless of the reachability state or stratum of its peer. By operating in this mode the host announces its willingness to synchronize and be synchronized by the peer. Symmetric Passive (2): This type of association is ordinarily created upon arrival of a message from a peer operating in the symmetric active mode and persists only as long as the peer is reachable and operating at a stratum level less than or equal to the host; otherwise, the association is dissolved. However, the association will always persist until at least one message has been sent in reply. By operating in this mode the host announces its willingness to synchronize and be synchronized by the peer. Client (3): A host operating in this mode sends periodic messages regardless of the reachability state or stratum of its peer. By operating in this mode the host, usually a LAN workstation, announces its willingness to be synchronized by, but not to synchronize the peer. Server (4): This type of association is ordinarily created upon arrival of a client request message and exists only in order to reply to that request, after which the association is dissolved. By operating in this mode the host, usually a LAN time server, announces its willingness to synchronize, but not to be synchronized by the peer. Broadcast (5): A host operating in this mode sends periodic messages regardless of the reachability state or stratum of the peers. By operating in this mode the host, usually a LAN time server operating on a high-speed broadcast medium, announces its willingness to synchronize all of the peers, but not to be synchronized by any of them. It seems to me, though, that any host except a leaf node would probably be in several modes. For example, I might have a local area network with three NTP servers, each in Symmetric Active (1) mode with respect to one another. They would also each be clients (3) of one of the many public stratum two time servers. Lastly, they would all server as servers (4) to the many local clients. Is the point that they're only in a given mode for a moment during the synchronization? If so, how does a host know to switch? I'm only looking for enough depth here to discuss the issue in an educated manner, not to write a custom time server.

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• Optimizing encrypted column search

  - by Sung Meister

  I have a table called,tblClient with an encrypted column called SSN. Due to company policy, we encrypted SSN using a symmetric key (chosen over asymmetric key due to performance reasons) using a password. Here is a partial LIKE search on SSN declare @SSN varchar(11) set @SSN = '111-22-%' open symmetric key SSN_KEY decrypt by password = 'secret' select Client_ID from tblClient (nolock) where convert(nvarchar(11), DECRYPTBYKEY(SSN)) like @SSN close symmetric key SSN_KEY Before encryption, searching thru 150,000 records took less than 1 second. but with the mix of decryption, the same search takes around 5 seconds. What strategy can I apply to try to optimize searching thru encrypted column?

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