Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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Explanation of SSL handshake with certificate

I've read a lot of articles. The client uses the information sent by the server to authenticate the server. If the server cannot be authenticated, the user is warned of the problem that an ...
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Confusing about Ephemeral Diffie-Hellman

1 Does Ephemeral Diffie-Hellman support authentication? Quote from www.rsa.com/products/bsafe/documentation/mesuite21html/dev_guide/group_EPH_DH.html Ephemeral Diffie-Hellman does NOT provide ...
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What is the difference between a Hash Function and a Cryptographic Hash Function?

I mean, is it just a matter of "how difficult is it to reverse the function with the current technology"? Or is there a mathematical concept or property that makes them different? If it is a matter ...
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TrueCrypt dataleaks that might betray the “Deniable File System” option

Reading into "Operation Satyagraha", one would have to believe give all the resources used that the investigators had some reason to believe there was data to decrypt, even though in theory and in ...
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id-ce-cRLDistributionPoints ASN.1 / DER encoding question

I have a file - test.pem - with the following contents: -----BEGIN CERTIFICATE----- MBIwEKAOoAwwCqMIMAZhBEFCQ0Q= -----END CERTIFICATE----- openssl asn1parse -inform PEM -in test.pem -i returns the ...
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OpenPGP: Sign-Verify workflow without Encrypt-Decrypt?

Is it a good and/or frequent practice to sign a file (with your own private key) without encrypting it (with the intended recipient's public key?) I haven't really been able to find a direct answer to ...
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question about implicitly tags in ASN.1

From the X.509 RFC, in the "Implicitly Tagged Module" section: CRLDistributionPoints ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint DistributionPoint ::= SEQUENCE { distributionPoint [0] ...
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493 views

How does FileVault 2 work with multiple decryption keys?

With FileVault 2, you can encrypt the hard-drive such that users on the computer can decrypt it with either of their passwords How does this work?
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Storage of 'secrets', keystores, HSMs and the rest

I've been digging for the past few days into storage of sentitive data. If I store this data in a database, I believe the general accepted practice is to store sensitive data encrypted, for various ...
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What voip client support manual encryption?

In pidgin there is a plugin that we can use to encrypt our messages in chat windows .. Is there anything simular for voip (pc to pc) ? any client that support manual encryption for voice data?(linux)
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Recommended Cipher Suites for TLS 1.0, 1.1 and 1.2

There are a lot of cipher suites defined in the in the specifications itself of TLS 1.0, 1.1 and 1.2. And furthermore, there exist RFCs which add even more cipher suites to a specific version (e.g. ...
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737 views

Is Data Object on openPGP smartcard v2 encrypted?

currently I thinking about on-the-fly disk encryption using Truecrypt/dmcrypt LUKS with key stored on smartcard. I would like to use openPGP v2 smart card, respectively GPF Cryptostick which is based ...
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How big salt should be?

I will be using scrypt to store passwords in my application. As such, I'll be using SHA-256 and Salsa20 crypto primitives (with PBKDF2). Having that in mind, how big salt should I use? Should it be ...
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3answers
178 views

Closed Port security

I have what I think is a security IT question (I'm more of a programmer myself). Assuming I am running a dedicated machine (say a PC) for a single program, meaning that the only port visible and open ...
2
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2answers
280 views

Does secure remote password verifier transmission need to happen out of band?

With relation to the necessity of a verifier being transmitted from the client to the server prior to any handshake steps, I was wondering how this is supposed to happen securely? To me this seems ...
4
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816 views

Bcrypt as a key derivation function?

I read a lot of entries at stack exchange about bcrypt and why it is supposed to be better than PBKDF2 in terms of password storage. I'm asking now if bcrypt is better than PBKDF2 in terms of key ...
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2answers
593 views

Zero padding in HMAC

Section 2 of RFC 2104 defines the key used in HMAC should be padded with zero bytes up to the block length of the underlying hash algorithm. Isn't this a potential security vulnerability since any key ...
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4answers
487 views

Base64 conversion for byte array in encryption

I am using ECC algorithm for security. Now the concern is I am placing the data in web page after encryption of the data in hex format and transmit to server and then it decrypts the data, but when I ...
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openssl_digest vs hash vs hash_hmac? Difference between SALT & HMAC?

openssl_digest vs hash vs hash_hmac I want to use SHA512 for storing password. Which of the above methods are best to use? Why? What is the difference between SALT & HMAC? I just read ...
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HMAC key value and security

What effect would there be if you used the same value you were hashing as the Key in an HMAC? For instance given the following example: message: "my secret message" nonce: ...
4
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1answer
820 views

X.509 algorithm identifier parameters vs. extension values

From the X.509 specs: AlgorithmIdentifier ::= SEQUENCE { algorithm OBJECT IDENTIFIER, parameters ANY DEFINED BY algorithm OPTIONAL } ...
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Why doesn't asn1parse parse all DER encoding strings?

I have a file - crl.txt - that contains the following: MDYwNKAyoDCGLmh0dHA6Ly93d3cyLnB1YmxpYy10cnVzdC5jb20vY3JsL2N0L2N0cm9vdC5jcmw= It's from one of the extensions in a particular X.509 cert. Why ...
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What is a cryptographic oracle?

I came across the term "cryptographic oracle" and despite a bit of googling I was unable to come across a clear, concise definition. What is a cryptographic oracle and what does it do? Can anyone ...
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1answer
336 views

Thoughts on creating unscalable conditions to brute force even small passwords?

I stumbled upon something called "scrypt" which claims to add fixed time/space complexity requirements into password-based key derivation. Quoting from their page: A simple password-based encryption ...
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parsing the id-ce-keyUsage extension in X.509 certs

I'm trying to decode an X.509 certificate and have a question regarding the decoding of the extensions. In particular, the octet string corresponding to id-ce-keyUsage (OID 2.5.29.15) is as follows: ...
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Methods of accessing CRLs

I'm creating custom certificates with CDP Definitions with the option of configuring several methods of accessing the CRL. My options are HTTP, LDAP, and FTP. What are best practices or should I say ...
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Is AES encrypting a password with itself more secure than SHA1?

This isn't really a practical question, but more a question of curiosity. I heard a CS professor recommend stepping up from md5ing passwords not to SHA1, but to AES encrypting the password using ...
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1answer
160 views

Does knowing encrypted information make it easier to find an unknown key?

I'm curious if knowing the exact content of an encrypted message or several messages makes it theoretically any easier to discover the encryption key. Does this speed up a brute force attack in any ...
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1answer
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static IV and random keys using aes-256-cbc

Are there any security risks in using a static IV if I generate a new random KEY for each set of data to encrypt? If I understand correctly what the purpose of the IV is in Cipher-block chaining mode ...
4
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1answer
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Rainbow tables, generation and lookup, preferably using GPU

1a) What software can I use to generate my own rainbow tables, preferably software that can utilize CUDA or ATI Stream? One of the reasons I want to make my own, is that I want to use a specific ...
2
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3answers
259 views

Help with SSL teaching material

I am taking a course on security next month. As the concepts of SSL/TSL are bit hard. I am looking for a nice way of presenting it to my students. They are Compsci undergrads. It would be nice to ...
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3answers
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Can I use a private key as a public key and vice versa?

I have code to encrypt data using a public key and decrypt it using a private key. This is useful when a client wants to send data to a server and know that only the server can decrypt it. But say I ...
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rsa certificate authorities

google.com's X.509 certificate issuer: http://www.flickr.com/photos/31717414@N06/6543437881/ The certificate authorities installed in my browser: http://www.flickr.com/photos/31717414@N06/6543437849/ ...
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2answers
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Keeping user data private in a cloud environment like Google App Engine

I am writing an open-source Java application for Google App Engine (GAE). The application will let users create content that is intended to be private. I want to provide reasonable assurances that ...
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1answer
333 views

Enterprise Encryption Considerations

What are the different aspects to consider for Enterprise Encryption policy? So far the resources I have are: https://www.owasp.org/index.php/Cryptographic_Storage_Cheat_Sheet ...
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3answers
442 views

Best protection against a “chosen-ciphertext” attack?

What is the best protection against a "chosen-ciphertext" attack when transmitting (=streaming) secured (=crypted) data via networks using the TCP protocol?
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How can I validate data on RFID chip that has RSA signatures and SHA1 hash values?

I have a RFID chip that has a digital signature using RSA and has data hashed using SHA1. I would like to compare data from the chip and user input in a program but I believe in order to do that I ...
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2answers
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Can the numbers on RSA SecurID tokens be predicted?

My workplace uses these SecurID tokens which provide you with a temporary password, the code will expire after a short time. I have always been fascinated by the things, because it seems as though ...
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ssh public/private key pair

I am having problems understanding how ssh really works. I know it uses a public key cryptography to encrypt messages. However, I can ssh to a server without first generating a public/private key pair ...
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571 views

Three Message Authentication Protocol

I have a protocol where "A" initiates communication with "B". "B" then sends a challenge to check if "A" is really "A". "B" does not remember sending the challenge so "A" has to respond by sending the ...
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5answers
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SHA, RSA and the relation between them

SHA is the hashing mechanism. However, RSA is the encryption algorithm. So does RSA algorithm use SHA hashing mechanism to generate hashing keys which in turn is used to encrypt the message?? ...
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2answers
915 views

Statistical data about the performance of various encryption algorithms

How can I find statistical data about the performance of various encryption systems, such as RSA, DSA, ECC etc?
5
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331 views

System for Mutual authenticaion and confidentiality

I am looking for a protocol where there needs to be mutual authentication between client and server. For example server should connect to a particular client only. That is client should authenticate ...
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Timing attacks on password hashes

Timing attacks can have a devastating impact in scenarios where the secret is involved, often in cases where byte-wise array comparison is used. Now there are those that advertise using constant ...
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Number of AES-256 operations per second on a maximized Cray XE6

How many FLOPs does one AES-256 operation take in ECB mode? How many AES-256 operations in ECB mode can a maximized Cray XE6 perform per second? Cray states that it can be scaled to over 1 million ...
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1answer
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Can Solaris' shadow hashes be created by better algorithms than the default DES-based hash?

By default, Solaris uses Traditional DES to encrypt password hashes in the shadow file. Is there a way to harden the security by changing this default behaviour and make it to be hashed using a ...
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What algorithms are best be cracked by GPU?

What algorithms are best being attacked by a GPU powered password cracker? For example, I heard that md5crypt that is being used in unix shadow file, is not the best choice for GPU cracking because it ...
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What does “key with length of x bits” mean?

I'd like to know what it means to say "the cryptosystem C uses keys with a length of x bits". I do not understand what the bits length means... doesn't it depend on the encoding? The same word encodes ...
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Select a TripleDES key so that it effectively behaves as regular DES

I'm working with a smartcard (DESFire) that supports both TripleDES and DES. In the specs it is stated that both modes of operation use 16 bytes keys. When the first 8 bytes in the key are identical ...
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550 views

What role does cryptography play in anti-piracy?

As a follow-up to Cipher for Product Registration, are there secure yet usable cryptographic standards/protocols for protecting software and data used by software? I'm interested in hardware and ...