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• Characteristics of an Initialization Vector

  - by Jamie Chapman

  I'm by no means a cryptography expert, I have been reading a few questions around Stack Overflow and on Wikipedia but nothing is really 'clear cut' in terms of defining an IV and it's usage. Points I have discovered: An IV is pre-pended to a plaintext message in order to strengthen the encryption The IV is truely random Each message has it's own unique IV Timestamps and cryptographic hashes are sometimes used instead of random values, but these are considered to be insecure as timestamps can be predicted One of the weaknesses of WEP (in 802.11) is the fact that the IV will reset after a specific amount of encryptions, thus repeating the IV I'm sure there are many other points to be made, what have I missed? (or misread!)

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• How to encrypt data in php using Public/Private keys?

  - by Xeoncross

  I have a small string of some data (less than 1kb) that I would like to have user agents pass to other sites when they are sent from my site. In order for the other sites to verify that I was the one that created the string I though of two options. The server pings me back to confirm (like paypal, openid, etc..) I use public/private keys to prove I sent the message (like PGP, DKIM, etc..) I don't want to setup HMAC because that would mean I have to use custom keys for each site which would be a pain. Out of those two choices it seems that #2 would save on bandwidth which makes it seem like a better choice. So how can you setup public/private key cryptography using PHP and are there any downsides?

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• Two-key encryption/decryption?

  - by Matt

  I'm looking to store some fairly sensitive data using PHP and MySQL and will be using some form of reversible encryption to do so since I need to get the data back out in plain text for it to be of any use. I'll be deriving the encryption key from the users' username/password combination but I'm stumped for what to do in the (inevitable) event of a password being forgotten. I realise that the purpose of encryption is that it can only be undone using the correct key but this must have been addressed before.. I'm trying to get my head around whether or not public key cryptography would apply to the problem but all I can think of is that the private key will still need to be correct to decrypt the data.. Any ideas?

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• Using Public/Private keys in reverse

  - by Wizzarding

  Hi, I have a situation where I need to make some data available for reading by anyone from a specific device, where the data is pre-loaded on the device, but I cannot allow anyone to create their own device and populate it with their own data in the same format. I know this sounds a little crazy, but there is a good reason! I was planning to use Public Key cryptography, encrypting the data with a public key, but then publishing the private key to anyone who wants to read the data. However, after looking at the RSACryptoServiceProvider and how it works it looks like I cannot just publish the private key as the private key can be used to create the public key. Could someone confirm that suspicion, or give me some hints on how I might be able to make this work! Many Thanks.

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• Simple integer encryption

  - by tloflin

  Is there a simple algorithm to encrypt integers? That is, a function E(i,k) that accepts an n-bit integer and a key (of any type) and produces another, unrelated n-bit integer that, when fed into a second function D(i,k) (along with the key) produces the original integer? Obviously there are some simple reversible operations you can perform, but they all seem to produce clearly related outputs (e.g. consecutive inputs lead to consecutive outputs). Also, of course, there are cryptographically strong standard algorithms, but they don't produce small enough outputs (e.g. 32-bit). I know any 32-bit cryptography can be brute-forced, but I'm not looking for something cryptographically strong, just something that looks random. Theoretically speaking it should be possible; after all, I could just create a dictionary by randomly pairing every integer. But I was hoping for something a little less memory-intensive.

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• .NET file Decryption - Bad Data

  - by Jon

  I am in the process of rewriting an old application. The old app stored data in a scoreboard file that was encrypted with the following code: private const String SSecretKey = @"?B?n?Mj?"; public DataTable GetScoreboardFromFile() { FileInfo f = new FileInfo(scoreBoardLocation); if (!f.Exists) { return setupNewScoreBoard(); } DESCryptoServiceProvider DES = new DESCryptoServiceProvider(); //A 64 bit key and IV is required for this provider. //Set secret key For DES algorithm. DES.Key = ASCIIEncoding.ASCII.GetBytes(SSecretKey); //Set initialization vector. DES.IV = ASCIIEncoding.ASCII.GetBytes(SSecretKey); //Create a file stream to read the encrypted file back. FileStream fsread = new FileStream(scoreBoardLocation, FileMode.Open, FileAccess.Read); //Create a DES decryptor from the DES instance. ICryptoTransform desdecrypt = DES.CreateDecryptor(); //Create crypto stream set to read and do a //DES decryption transform on incoming bytes. CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read); DataTable dTable = new DataTable("scoreboard"); dTable.ReadXml(new StreamReader(cryptostreamDecr)); cryptostreamDecr.Close(); fsread.Close(); return dTable; } This works fine. I have copied the code into my new app so that I can create a legacy loader and convert the data into the new format. The problem is I get a "Bad Data" error: System.Security.Cryptography.CryptographicException was unhandled Message="Bad Data.\r\n" Source="mscorlib" The error fires at this line: dTable.ReadXml(new StreamReader(cryptostreamDecr)); The encrypted file was created today on the same machine with the old code. I guess that maybe the encryption / decryption process uses the application name / file or something and therefore means I can not open it. Does anyone have an idea as to: A) Be able explain why this isn't working? B) Offer a solution that would allow me to be able to open files that were created with the legacy application and be able to convert them please? Here is the whole class that deals with loading and saving the scoreboard: using System; using System.Collections.Generic; using System.Text; using System.Security.Cryptography; using System.Runtime.InteropServices; using System.IO; using System.Data; using System.Xml; using System.Threading; namespace JawBreaker { [Serializable] class ScoreBoardLoader { private Jawbreaker jawbreaker; private String sSecretKey = @"?B?n?Mj?"; private String scoreBoardFileLocation = ""; private bool keepScoreBoardUpdated = true; private int intTimer = 180000; public ScoreBoardLoader(Jawbreaker jawbreaker, String scoreBoardFileLocation) { this.jawbreaker = jawbreaker; this.scoreBoardFileLocation = scoreBoardFileLocation; } // Call this function to remove the key from memory after use for security [System.Runtime.InteropServices.DllImport("KERNEL32.DLL", EntryPoint = "RtlZeroMemory")] public static extern bool ZeroMemory(IntPtr Destination, int Length); // Function to Generate a 64 bits Key. private string GenerateKey() { // Create an instance of Symetric Algorithm. Key and IV is generated automatically. DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create(); // Use the Automatically generated key for Encryption. return ASCIIEncoding.ASCII.GetString(desCrypto.Key); } public void writeScoreboardToFile() { DataTable tempScoreBoard = getScoreboardFromFile(); //add in the new scores to the end of the file. for (int i = 0; i < jawbreaker.Scoreboard.Rows.Count; i++) { DataRow row = tempScoreBoard.NewRow(); row.ItemArray = jawbreaker.Scoreboard.Rows[i].ItemArray; tempScoreBoard.Rows.Add(row); } //before it is written back to the file make sure we update the sync info if (jawbreaker.SyncScoreboard) { //connect to webservice, login and update all the scores that have not been synced. for (int i = 0; i < tempScoreBoard.Rows.Count; i++) { try { //check to see if that row has been synced to the server if (!Boolean.Parse(tempScoreBoard.Rows[i].ItemArray[7].ToString())) { //sync info to server //update the row to say that it has been updated object[] tempArray = tempScoreBoard.Rows[i].ItemArray; tempArray[7] = true; tempScoreBoard.Rows[i].ItemArray = tempArray; tempScoreBoard.AcceptChanges(); } } catch (Exception ex) { jawbreaker.writeErrorToLog("ERROR OCCURED DURING SYNC TO SERVER UPDATE: " + ex.Message); } } } FileStream fsEncrypted = new FileStream(scoreBoardFileLocation, FileMode.Create, FileAccess.Write); DESCryptoServiceProvider DES = new DESCryptoServiceProvider(); DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey); DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey); ICryptoTransform desencrypt = DES.CreateEncryptor(); CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write); MemoryStream ms = new MemoryStream(); tempScoreBoard.WriteXml(ms, XmlWriteMode.WriteSchema); ms.Position = 0; byte[] bitarray = new byte[ms.Length]; ms.Read(bitarray, 0, bitarray.Length); cryptostream.Write(bitarray, 0, bitarray.Length); cryptostream.Close(); ms.Close(); //now the scores have been added to the file remove them from the datatable jawbreaker.Scoreboard.Rows.Clear(); } public void startPeriodicScoreboardWriteToFile() { while (keepScoreBoardUpdated) { //three minute sleep. Thread.Sleep(intTimer); writeScoreboardToFile(); } } public void stopPeriodicScoreboardWriteToFile() { keepScoreBoardUpdated = false; } public int IntTimer { get { return intTimer; } set { intTimer = value; } } public DataTable getScoreboardFromFile() { FileInfo f = new FileInfo(scoreBoardFileLocation); if (!f.Exists) { jawbreaker.writeInfoToLog("Scoreboard not there so creating new one"); return setupNewScoreBoard(); } else { DESCryptoServiceProvider DES = new DESCryptoServiceProvider(); //A 64 bit key and IV is required for this provider. //Set secret key For DES algorithm. DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey); //Set initialization vector. DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey); //Create a file stream to read the encrypted file back. FileStream fsread = new FileStream(scoreBoardFileLocation, FileMode.Open, FileAccess.Read); //Create a DES decryptor from the DES instance. ICryptoTransform desdecrypt = DES.CreateDecryptor(); //Create crypto stream set to read and do a //DES decryption transform on incoming bytes. CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read); DataTable dTable = new DataTable("scoreboard"); dTable.ReadXml(new StreamReader(cryptostreamDecr)); cryptostreamDecr.Close(); fsread.Close(); return dTable; } } public DataTable setupNewScoreBoard() { //scoreboard info into dataset DataTable scoreboard = new DataTable("scoreboard"); scoreboard.Columns.Add(new DataColumn("playername", System.Type.GetType("System.String"))); scoreboard.Columns.Add(new DataColumn("score", System.Type.GetType("System.Int32"))); scoreboard.Columns.Add(new DataColumn("ballnumber", System.Type.GetType("System.Int32"))); scoreboard.Columns.Add(new DataColumn("xsize", System.Type.GetType("System.Int32"))); scoreboard.Columns.Add(new DataColumn("ysize", System.Type.GetType("System.Int32"))); scoreboard.Columns.Add(new DataColumn("gametype", System.Type.GetType("System.String"))); scoreboard.Columns.Add(new DataColumn("date", System.Type.GetType("System.DateTime"))); scoreboard.Columns.Add(new DataColumn("synced", System.Type.GetType("System.Boolean"))); scoreboard.AcceptChanges(); return scoreboard; } private void Run() { // For additional security Pin the key. GCHandle gch = GCHandle.Alloc(sSecretKey, GCHandleType.Pinned); // Remove the Key from memory. ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2); gch.Free(); } } }

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• SHA1 hashing in Delphi XE

  - by Leonardo Herrera

  Hello, I'm in the process of implementing XML digital signatures. I'm starting with little steps, so right now I want to solve the problem of SHA-1 hashing. There are lots of questions about this in SO: Digitially Sign Key with Lockbox Encryption library for Delphi Convert this php digital signing to Delphi Delphi: is there a version of LockBox for Delphi-XE Delphi 2010 Cryptography libraries ...and probably more. However, I'm using Delphi XE. So far, I've tried LockBox 2 (both the Songbeamer and Sourceforge versions), Lock Box 3, DCPCrypto2 and some others (Hashes is an easy to use unit which uses Windows crypto functions) I prepared a small test rig that gives me the following: LockBox2 FAILED: 1 ('abc') Got: '9f04f41a848514162050e3d68c1a7abb441dc2b5' Expected: 'a9993e364706816aba3e25717850c26c9cd0d89d' FAILED: 2 ('abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq') Got: '51d7d8769ac72c409c5b0e3f69c60adc9a039014' Expected: '84983e441c3bd26ebaae4aa1f95129e5e54670f1' LockBox3 FAILED: 1 ('abc') Got: '9f04f41a848514162050e3d68c1a7abb441dc2b5' Expected: 'a9993e364706816aba3e25717850c26c9cd0d89d' FAILED: 2 ('abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq') Got: '51d7d8769ac72c409c5b0e3f69c60adc9a039014' Expected: '84983e441c3bd26ebaae4aa1f95129e5e54670f1' DCPCrypto2 FAILED: 1 ('abc') Got: '9f04f41a848514162050e3d68c1a7abb441dc2b5' Expected: 'a9993e364706816aba3e25717850c26c9cd0d89d' FAILED: 2 ('abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq') Got: '51d7d8769ac72c409c5b0e3f69c60adc9a039014' Expected: '84983e441c3bd26ebaae4aa1f95129e5e54670f1' Hashes Test 1 passes Test 2 passes Have you succeeded in compile the mentioned libraries under Delphi XE and make them give the appropriate values? I'm particularly interested in DCPCrypt2 SelfTest procedure. Edit: I've added this answer with the fixed source code. Thank you all for your help, it is most appreciated.

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• Password Cracking in 2010 and Beyond

  - by mttr

  I have looked a bit into cryptography and related matters during the last couple of days and am pretty confused by now. I have a question about password strength and am hoping that someone can clear up my confusion by sharing how they think through the following questions. I am becoming obsessed about these things, but need to spend my time otherwise :-) Let's assume we have an eight-digit password that consists of upper and lower-case alphabetic characters, numbers and common symbols. This means we have 8^96 ~= 7.2 quadrillion different possible passwords. As I understand there are at least two approaches to breaking this password. One is to try a brute-force attack where we try to guess each possible combination of characters. How many passwords can modern processors (in 2010, Core i7 Extreme for eg) guess per second (how many instructions does a single password guess take and why)? My guess would be that it takes a modern processor in the order of years to break such a password. Another approach would consist of obtaining a hash of my password as stored by operating systems and then search for collisions. Depending on the type of hash used, we might get the password a lot quicker than by the bruteforce attack. A number of questions about this: Is the assertion in the above sentence correct? How do I think about the time it takes to find collisions for MD4, MD5, etc. hashes? Where does my Snow Leopard store my password hash and what hashing algorithm does it use? And finally, regardless of the strength of file encryption using AES-128/256, the weak link is still my en/decryption password used. Even if breaking the ciphered text would take longer than the lifetime of the universe, a brute-force attack on my de/encryption password (guess password, then try to decrypt file, try next password...), might succeed a lot earlier than the end of the universe. Is that correct? I would be very grateful, if people could have mercy on me and help me think through these probably simple questions, so that I can get back to work.

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• implementing cryptographic algorithms, specifically the key expansion part

  - by masseyc

  Hey, recently I picked up a copy of Applied Cryptography by Bruce Schneier and it's been a good read. I now understand how several algorithms outlined in the book work, and I'd like to start implementing a few of them in C. One thing that many of the algorithms have in common is dividing an x-bit key, into several smaller y-bit keys. For example, blowfish's key, X, is 64-bits, but you are required to break it up into two 32-bit halves; Xl and Xr. This is where I'm getting stuck. I'm fairly decent with C, but I'm not the strongest when it comes to bitwise operators and the like. After some help on IRC, I managed to come up with these two macros: #define splitup(a, b, c) {b = a >> 32; c = a & 0xffffffff; } #define combine(a, b, c) {a = (c << 32) | a;} Where a is 64 bits and b and c are 32 bits. However, the compiler warns me about the fact that I'm shifting a 32 bit variable by 32 bits. My questions are these: what's bad about shifting a 32-bit variable 32 bits? I'm guessing it's undefined, but these macros do seem to be working. Also, would you suggest I go about this another way? As I said, I'm fairly familiar with C, but bitwise operators and the like still give me a headache.

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• I just wanted to DES 4096 bytes of data with a 128 bits key...

  - by badp

  ...and what the nice folks at OpenSSL gratiously provide me with is this. :) Now, since you shouldn't be guessing when using cryptography, I come here for confirmation: what is the function call I want to use? What I understood A 128 bits key is 16 byte large, so I'll need double DES (2 × 8 byte). This leaves me with only a few function calls: void DES_ede2_cfb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc); void DES_ede2_cbc_encrypt(const unsigned char *input, unsigned char *output, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int enc); void DES_ede2_cfb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc); void DES_ede2_ofb64_encrypt(const unsigned char *in, unsigned char *out, long length, DES_key_schedule *ks1, DES_key_schedule *ks2, DES_cblock *ivec, int *num); In this case, I guess the function I want to call DES_ede2_cfb64_encrypt, although I'm not so sure -- I definitely don't need padding here and I'd have to care about what ivec and num are, and how I want to generate them... What am I missing?

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• Converting a byte array to a X.509 certificate

  - by ddd

  I'm trying to port a piece of Java code into .NET that takes a Base64 encoded string, converts it to a byte array, and then uses it to make a X.509 certificate to get the modulus & exponent for RSA encryption. This is the Java code I'm trying to convert: byte[] externalPublicKey = Base64.decode("base 64 encoded string"); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(externalPublicKey); Key publicKey = keyFactory.generatePublic(publicKeySpec); RSAPublicKey pbrtk = (java.security.interfaces.RSAPublicKey) publicKey; BigInteger modulus = pbrtk.getModulus(); BigInteger pubExp = pbrtk.getPublicExponent(); I've been trying to figure out the best way to convert this into .NET. So far, I've come up with this: byte[] bytes = Convert.FromBase64String("base 64 encoded string"); X509Certificate2 x509 = new X509Certificate2(bytes); RSA rsa = (RSA)x509.PrivateKey; RSAParameters rsaParams = rsa.ExportParameters(false); byte[] modulus = rsaParams.Modulus; byte[] exponent = rsaParams.Exponent; Which to me looks like it should work, but it throws an exception when I use the base 64 encoded string from the Java code to generate the X509 certificate. Is Java's X.509 implementation just incompatible with .NET's, or am I doing something wrong in my conversion from Java to .NET? Or is there simply no conversion from Java to .NET in this case?

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• AesManaged and RijndaelManaged

  - by xscape

  Im currently developing a Silverlight application that connects to an old webservice. Our old webservice uses an encryption tool which silverlight does not support. Finally, we decided to used AesManaged for encryption, however, our webservice does not support AesManaged. Is their a way to decrypt an AesManaged to RijndaelManaged? If yes, can you please post a sample snippet? Your feedback is highly needed. Thank you.

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• RSA decrypting data in C# (.NET 3.5) which was encrypted with openssl in php 5.3.2

  - by panny

  Maybe someone can clear me up. I have been surfing on this a while now. Step #1: Create a root certificate Key generation on unix 1) openssl req -x509 -nodes -days 3650 -newkey rsa:1024 -keyout privatekey.pem -out mycert.pem 2) openssl rsa -in privatekey.pem -pubout -out publickey.pem 3) openssl pkcs12 -export -out mycertprivatekey.pfx -in mycert.pem -inkey privatekey.pem -name "my certificate" Step #2: Does root certificate work on php: YES PHP side I used the publickey.pem to read it into php: $publicKey = "file://C:/publickey.pem"; $privateKey = "file://C:/privatekey.pem"; $plaintext = "123"; openssl_public_encrypt($plaintext, $encrypted, $publicKey); $transfer = base64_encode($encrypted); openssl_private_decrypt($encrypted, $decrypted, $privateKey); echo $decrypted; // "123" OR $server_public_key = openssl_pkey_get_public(file_get_contents("C:\publickey.pem")); // rsa encrypt openssl_public_encrypt("123", $encrypted, $server_public_key); and the privatekey.pem to check if it works: openssl_private_decrypt($encrypted, $decrypted, openssl_get_privatekey(file_get_contents("C:\privatekey.pem"))); echo $decrypted; // "123" Coming to the conclusion, that encryption/decryption works fine on the php side with these openssl root certificate files. Step #3: Does root certificate work on .NET: YES C# side In same manner I read the keys into a .net C# console program: X509Certificate2 myCert2 = new X509Certificate2(); RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); try { myCert2 = new X509Certificate2(@"C:\mycertprivatekey.pfx"); rsa = (RSACryptoServiceProvider)myCert2.PrivateKey; } catch (Exception e) { } byte[] test = {Convert.ToByte("123")}; string t = Convert.ToString(rsa.Decrypt(rsa.Encrypt(test, false), false)); Coming to the point, that encryption/decryption works fine on the c# side with these openssl root certificate files. Step #4: Enrypt in php and Decrypt in .NET: !!NO!! PHP side $onett = "123" .... openssl_public_encrypt($onett, $encrypted, $server_public_key); $onettbase64 = base64_encode($encrypted); copy - paste $onettbase64 ("LkU2GOCy4lqwY4vtPI1JcsxgDgS2t05E6kYghuXjrQe7hSsYXETGdlhzEBlp+qhxzTXV3pw+AS5bEg9CPxqHus8fXHOnXYqsd2HL20QSaz+FjZee6Kvva0cGhWkFdWL+ANDSOWRWo/OMhm7JVqU3P/44c3dLA1eu2UsoDI26OMw=") into c# program: C# side byte[] transfered_onettbase64 = Convert.FromBase64String("LkU2GOCy4lqwY4vtPI1JcsxgDgS2t05E6kYghuXjrQe7hSsYXETGdlhzEBlp+qhxzTXV3pw+AS5bEg9CPxqHus8fXHOnXYqsd2HL20QSaz+FjZee6Kvva0cGhWkFdWL+ANDSOWRWo/OMhm7JVqU3P/44c3dLA1eu2UsoDI26OMw="); string k = Convert.ToString(rsa.Decrypt(transfered_onettbase64, false)); // Bad Data exception == Exception while decrypting!!! Any ideas?

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• ProtectedData.Unprotect() after Impersonate()

  - by Andrey

  The following code doesn't work: IntPtr token = Win32Dll.LogonUser(“user1”, “mydomain”, “password1”); WindowsIdentity id = new WindowsIdentity(token); WindowsImpersonationContext ic = id.Impersonate(); byte[] unprotectedBytes = ProtectedData.Unprotect(passwordBytes, null, DataProtectionScope.CurrentUser); password = Encoding.Unicode.GetString(unprotectedBytes); ic.Undo(); The password is not decrypted. MSDN said "If you use this method during impersonation, you may receive the following error: "Key not valid for use in specified state." This error can be prevented by loading the profile of the user you want to impersonate, before calling the method." I would be very grateful for the help!

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• Using M2Crypto to save and load X509 certs in pem files

  - by Brock Pytlik

  I would expect that if I have a X509 cert as an object in memory, saved it as a pem file, then loaded it back in, I would end up with the same cert I started with. This seems not to be the case however. Let's call the original cert A, and the cert loaded from the pem file B. A.as_text() is identical to B.as_text(), but A.as_pem() differs from B.as_pem(). To say the least, I'm confused by this. As a side note, if A has been signed by another entity C, then A will verify against C's cert, but B will not. I've put together a tiny sample program to demonstrate what I'm seeing. When I run this, the second RuntimeError is raised. Thanks, Brock #!/usr/bin/python2.6 import M2Crypto as m2 import time cur_time = m2.ASN1.ASN1_UTCTIME() cur_time.set_time(int(time.time()) - 60*60*24) expire_time = m2.ASN1.ASN1_UTCTIME() # Expire certs in 1 hour. expire_time.set_time(int(time.time()) + 60 * 60 * 24) cs_rsa = m2.RSA.gen_key(1024, 65537, lambda: None) cs_pk = m2.EVP.PKey() cs_pk.assign_rsa(cs_rsa) cs_cert = m2.X509.X509() # These two seem the minimum necessary to make the as_text function call work # at all cs_cert.set_not_before(cur_time) cs_cert.set_not_after(expire_time) # This seems necessary to fill out the complete cert without errors. cs_cert.set_pubkey(cs_pk) # I've tried with the following set lines commented out and not commented. cs_name = m2.X509.X509_Name() cs_name.C = "US" cs_name.ST = "CA" cs_name.OU = "Fake Org CA 1" cs_name.CN = "www.fakeorg.dex" cs_name.Email = "[email protected]" cs_cert.set_subject(cs_name) cs_cert.set_issuer_name(cs_name) cs_cert.sign(cs_pk, md="sha256") orig_text = cs_cert.as_text() orig_pem = cs_cert.as_pem() print "orig_text:\n%s" % orig_text cs_cert.save_pem("/tmp/foo") tcs = m2.X509.load_cert("/tmp/foo") tcs_text = tcs.as_text() tcs_pem = tcs.as_pem() if orig_text != tcs_text: raise RuntimeError( "Texts were different.\nOrig:\n%s\nAfter load:\n%s" % (orig_text, tcs_text)) if orig_pem != tcs_pem: raise RuntimeError( "Pems were different.\nOrig:\n%s\nAfter load:\n%s" % (orig_pem, tcs_pem))

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• Generate authenticated CMSEnvelopedData Messages with bouncycastle

  - by levinalex

  I am trying to encrypt data with a password and store it inside a ASN.1 encoded CMS message (using C# and BouncyCastle 1.4) The code I have seems to have two problems: the data does not seem to be signed with a HMAC, so when I tamper with the encodedData (by enabling the commented out line), the decryption still succeeds. when I decrypt the data I have tampered with, I get beck corrupted plain text. However only a two blocks of plaintext data are corrupted. This seems to suggest that the encryption does not actually use CBC mode. (edit: disregard the second point, this is exactly how CBC is supposed to work) This is what I am testing with: public void TestMethod1() { byte[] data = new byte[1024]; // plaintext: a list of zeroes CmsEnvelopedDataGenerator generator = new CmsEnvelopedDataGenerator(); CmsPbeKey encryptionKey = new Pkcs5Scheme2PbeKey("foo", new byte[] { 1, 2, 3 }, 2048); generator.AddPasswordRecipient(encryptionKey, CmsEnvelopedDataGenerator.Aes256Cbc); CmsProcessableByteArray cmsByteArray = new CmsProcessableByteArray(data); CmsEnvelopedData envelopeData = generator.Generate(cmsByteArray, CmsEnvelopedDataGenerator.Aes256Cbc); byte[] encodedData = envelopeData.GetEncoded(); // encodedData[500] = 10; // tamper with the data RecipientID recipientID = new RecipientID(); CmsEnvelopedData decodedEnvelopeData = new CmsEnvelopedData(encodedData); RecipientInformation recipient = decodedEnvelopeData.GetRecipientInfos().GetFirstRecipient(recipientID); byte[] data2 = recipient.GetContent(encryptionKey); CollectionAssert.AreEqual(data, data2); } What am I doing wrong? What would be the correct way to write this?

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• BouncyCastle GCM/CCM Exceprion in JAVA

  - by 4r1y4n

  can anyone give me an example for using GCM and/or CCM modes with AES in BouncyCastle? My code is this: SecretKeySpec key = new SecretKeySpec(keyBytes, "AES"); IvParameterSpec ivSpec = new IvParameterSpec(ivBytes); Cipher cipher = Cipher.getInstance("AES/AEAD/PKCS5Padding", "BC"); byte[] block = new byte[1048576]; int i; long st,et; cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec); BufferedInputStream bIn=new BufferedInputStream(new ProgressMonitorInputStream(null,"Encrypting ...",new FileInputStream("input"))); CipherInputStream cIn = new CipherInputStream(bIn, cipher); BufferedOutputStream bOut=new BufferedOutputStream(new FileOutputStream("output.enc")); int ch; while ((i = cIn.read(block)) != -1) { bOut.write(block, 0, i); } cIn.close(); bOut.close(); Thread.sleep(5000); cipher.init(Cipher.DECRYPT_MODE, key, ivSpec); BufferedInputStream fis=new BufferedInputStream(new ProgressMonitorInputStream(null,"Decrypting ...",new FileInputStream("output.enc"))); //FileInputStream fis=new FileInputStream("output.enc"); //FileOutputStream ro=new FileOutputStream("regen.plain"); BufferedOutputStream ro=new BufferedOutputStream(new FileOutputStream("regen.plain")); CipherInputStream dcIn = new CipherInputStream(fis, cipher); while ((i = dcIn.read(block)) != -1) { ro.write(block, 0, i); } dcIn.close(); ro.close(); but it throws this exception when decrypting in GCM mode (line 70 is bOut.write(block, 0, i);): Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException at java.lang.System.arraycopy(Native Method) at org.bouncycastle.crypto.modes.CCMBlockCipher.processPacket(Unknown Source) at org.bouncycastle.crypto.modes.CCMBlockCipher.doFinal(Unknown Source) at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher$AEADGenericBlockCipher.doFinal(Unknown Source) at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(Unknown Source) at javax.crypto.Cipher.doFinal(DashoA13*..) at javax.crypto.CipherInputStream.a(DashoA13*..) at javax.crypto.CipherInputStream.read(DashoA13*..) at javax.crypto.CipherInputStream.read(DashoA13*..) at enctest.Main.main(Main.java:70) And this Exception when encrypting in CCM mode (line 70 is bOut.write(block, 0, i);): Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException at java.lang.System.arraycopy(Native Method) at org.bouncycastle.crypto.modes.CCMBlockCipher.processPacket(Unknown Source) at org.bouncycastle.crypto.modes.CCMBlockCipher.doFinal(Unknown Source) at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher$AEADGenericBlockCipher.doFinal(Unknown Source) at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(Unknown Source) at javax.crypto.Cipher.doFinal(DashoA13*..) at javax.crypto.CipherInputStream.a(DashoA13*..) at javax.crypto.CipherInputStream.read(DashoA13*..) at javax.crypto.CipherInputStream.read(DashoA13*..) at enctest.Main.main(Main.java:70)

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• Generating a salt in PHP

  - by qster

  What's the best way to generate a cryptographically secure 32 bytes salt in PHP, without depending on libraries seldom included in typical PHP installations? After some googling I discovered that mt_rand is not considered secure enough, but I haven't found a suggestion for a replacement. One article suggested reading from /dev/random but not only this won't work on windows; it is also very slow. I want a reasonable balance between security and speed (ie, it shouldn't take 20 seconds to generate 512 bytes, like /dev/random usually does)

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• How to use Bouncy Castle lightweight API with AES and PBE

  - by Adrian

  I have a block of ciphertext that was created using the JCE algorithim "PBEWithSHA256And256BitAES-CBC-BC". The provider is BouncyCastle. What I'd like to do it decrypt this ciphertext using the BouncyCastle lightweight API. I don't want to use JCE because that requires installing the Unlimited Strength Jurisdiction Policy Files. Documentation seems to be thin on the ground when it comes to using BC with PBE and AES. Here's what I have so far. The decryption code runs without exception but returns rubbish. The encryption code, String password = "qwerty"; String plainText = "hello world"; byte[] salt = generateSalt(); byte[] cipherText = encrypt(plainText, password.toCharArray(), salt); private static byte[] generateSalt() throws NoSuchAlgorithmException { byte salt[] = new byte[8]; SecureRandom saltGen = SecureRandom.getInstance("SHA1PRNG"); saltGen.nextBytes(salt); return salt; } private static byte[] encrypt(String plainText, char[] password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException { Security.addProvider(new BouncyCastleProvider()); PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, 20); PBEKeySpec pbeKeySpec = new PBEKeySpec(password); SecretKeyFactory keyFac = SecretKeyFactory.getInstance("PBEWithSHA256And256BitAES-CBC-BC"); SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec); Cipher encryptionCipher = Cipher.getInstance("PBEWithSHA256And256BitAES-CBC-BC"); encryptionCipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec); return encryptionCipher.doFinal(plainText.getBytes()); } The decryption code, byte[] decryptedText = decrypt(cipherText, password.getBytes(), salt); private static byte[] decrypt(byte[] cipherText, byte[] password, byte[] salt) throws DataLengthException, IllegalStateException, InvalidCipherTextException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException { BlockCipher engine = new AESEngine(); CBCBlockCipher cipher = new CBCBlockCipher(engine); PKCS5S1ParametersGenerator keyGenerator = new PKCS5S1ParametersGenerator(new SHA256Digest()); keyGenerator.init(password, salt, 20); CipherParameters keyParams = keyGenerator.generateDerivedParameters(256); cipher.init(false, keyParams); byte[] decryptedBytes = new byte[cipherText.length]; int numBytesCopied = cipher.processBlock(cipherText, 0, decryptedBytes, 0); return decryptedBytes; }

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• Using one key for Encryption and HMAC

  - by Vladimir

  Hello, I am wondering whether I can use a shared secret key established between two clients as the HMAC key too. I saw that there is a problem when it is used as a CBC-MAC but I haven't found any evidence it is bad practice for HMACs. Thanks, Vladimir

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• Import .pem public and private keys to JKS keystore

  - by Rolf

  Hi, I have public and private keys in separate .pem files that I would need to get into a JKS keystore somehow. Tried using the -import command in KeyTool for this, which gives an "not an X.509 certificate" error. I'm guessing the solution has to do with OpenSSL, but I'm not entirely sure what to do with it. Would really appreciate any help with this, since I'm completely clueless with everything crypto-related. Thanks in advance, --Rolf

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• Using blowfish encryption with Android?

  - by haseman

  I'm trying to use a blowfish cipher inside and Android application. It appears that the Android platform supports blowfish (it appears to be in the source code), but when I try to get a cipher using: Cipher.getInstance("blowfish"); I get a "java.security.NoSuchAlgorithmException"

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• C# HMAC Implementation Problem

  - by Emanuel

  I want my application to encrypt a user password, and at one time password will be decrypted to be sent to the server for authentication. A friend advise me to use HMAC. I wrote the following code in C#: System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); byte[] key = encoding.GetBytes("secret"); HMACSHA256 myhmacsha256 = new HMACSHA256(key); byte[] hashValue = myhmacsha256.ComputeHash(encoding.GetBytes("text")); string resultSTR = Convert.ToBase64String(hashValue); myhmacsha256.Clear(); How to decode the password (resultSTR, in this case)? Thanks.

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• How do I use m2crypto to validate a X509 certificate chain in a non-SSL setting

  - by Brock Pytlik

  I'm trying to figure out how to, using m2crypto, validate the chain of trust from a public key version of a X509 certificate back to one of a set of known root CA's when the chain may be arbitrarily long. The SSL.Context module looks promising except that I'm not doing this in the context of a SSL connection and I can't see how the information passed to load_verify_locations is used. Essentially, I'm looking for the interface that's equivalent to: openssl verify pub_key_x509_cert Is there something like that in m2crypto? Thanks.

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• File not found on RSACryptoServiceProvider, service account permissions?

  - by Ben Scheirman

  Our web service wraps around a third party library that contains the following code. We are using an Active Directory service account in the IIS 6 app pool (no interactive login abilities). Our service fails with the error “The system cannot find the file specified”. We’ve traced the error to the “RSACryptoServiceProvider provider = new RSACryptoServiceProvider();”. The third party assembly depends on a x509 file based certificate for its encryption process and the Service Account has Read / Write access to the keys folder. Additionally, the service account has Read, Write, Modify rights to “C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys”. Code: StringBuilder builder = new StringBuilder(publicKeyData); builder.Replace("-----BEGIN CERTIFICATE-----", ""); builder.Replace("-----END CERTIFICATE-----", ""); X509Certificate2 certificate = new X509Certificate2( Convert.FromBase64String(builder.ToString())); string xmlString = certificate.PublicKey.Key.ToXmlString(false); RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); //BOOM CspKeyContainerInfo containerInfo = provider.CspKeyContainerInfo; provider.PersistKeyInCsp = false; provider.FromXmlString(xmlString); loadedKeys.Add(key, provider); provider2 = provider; We cracked open FileMon and noticed that there is a FILE NOT FOUND for that AppPool, followed by another SUCCESS for the same exact file. I'm out of my element here, anybody have an idea as to why we're seeing this?

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