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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790 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 ...
5
votes
2answers
568 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 ...
3
votes
4answers
485 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 ...
4
votes
2answers
2k views

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 ...
3
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2answers
3k views

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
votes
1answer
799 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 } ...
3
votes
1answer
989 views

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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votes
3answers
2k views

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 ...
4
votes
1answer
331 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 ...
3
votes
1answer
1k views

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: ...
4
votes
2answers
95 views

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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votes
6answers
6k views

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 ...
3
votes
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 ...
2
votes
1answer
1k views

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
votes
1answer
2k views

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
votes
3answers
257 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 ...
5
votes
3answers
3k views

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 ...
1
vote
2answers
92 views

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/ ...
5
votes
2answers
1k views

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 ...
0
votes
1answer
329 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 ...
0
votes
3answers
437 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?
4
votes
1answer
399 views

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 ...
8
votes
2answers
5k views

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 ...
6
votes
2answers
2k views

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 ...
1
vote
3answers
562 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 ...
5
votes
5answers
7k views

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?? ...
3
votes
2answers
898 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
votes
2answers
329 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 ...
14
votes
1answer
2k views

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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votes
3answers
2k views

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 ...
1
vote
1answer
1k views

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 ...
5
votes
2answers
2k views

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 ...
9
votes
5answers
8k views

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 ...
6
votes
1answer
984 views

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 ...
8
votes
1answer
541 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 ...
14
votes
5answers
4k views

What does Amazon's S3 Server-side encryption protect against?

Amazon's S3 storage service offers server-side encryption of objects, automatically managed for the user (Amazon's Documentation). It's easy to enable so I'm thinking "why not?", but what kind of ...
8
votes
5answers
1k views

Save private messages encrypted in database

I'm not sure if this question fits better in StackOverflowSE or CryptoSE but i think this is the right place. In an online community portal I want to save users' private messages encrypted in a ...
4
votes
3answers
629 views

PHP/JavaScript with RSA

I have a few columns in the database which should be encrypted. I'm wondering if the way I chose to make this system work is ok, and I'm looking forward to hear some opinions: I chose RSA algorithm ...
5
votes
2answers
270 views

Do any crypto libraries take advantage of Windows GPU API “Direct Compute”?

Are there any encryption (decryption?) libraries that take advantage of the Windows GPU API?
13
votes
4answers
3k views

How quickly can these password schemes really be beaten?

If you use a quick hashing algorithm like MD5 or SHA-1 to hash passwords and you don't use any salt at all, how quickly could one expect a hacker to find my password out? If I use a truly random salt ...
2
votes
3answers
2k views

RSA 4096 with AES 256 Encryption Process Using PyCrypto

I have the following process for encrypting and decrypting data in a python script using the PyCrypto module: Encryption - Server A AES 256 shared key is generated Associated IV is generated Data ...
21
votes
3answers
8k views

Which SSL/TLS ciphers can be considered secure?

The OpenSSL website provides a long list of different ciphers available for SSL and TLS. My question is, which of those ciphers can be considered secure nowadays. I am especially interested in HTTPS, ...
6
votes
2answers
5k views

Is it possible to speed up WPA/WPA2-PSK cracking using a rogue AP?

We know that WPA/WPA2-PSK uses a PTK (Pairwise Transient Key) for each client to encrypt the communication. This PTK is generated through the process known as 4-way handshake. As told in the related ...
2
votes
4answers
102 views

Securely signing a container package

I have a desktop application that uses a kind of package format to load a blob and do something with it. To ensure the authenticity of the blob, I would like to add a digital signature. I researched ...
6
votes
3answers
3k views

Generate a PGP key with more than 4096 bits?

I would like to know if generating a PGP key with a number of bits higher than 4096 is possible and if so how?
3
votes
1answer
2k views

Are Windows password hashes salted with the user name?

I'll readily admit I'm pretty clueless when it comes to cryptography, so there may already be some false assumptions in the question title itself :-) Still, I "heard" that it is more secure to store ...
10
votes
4answers
5k views

OS with encrypted RAM?

Are there any applications, JIT frameworks or operating systems that focus on encrypted virtual memory, or perhaps virtual machines that do something similar? I know there are processors (albeit old, ...
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vote
2answers
999 views

Need example and working Security Token Service (STS)?

Can anyone explain or post any link to a simple example and introduction about the Security Token Service (STS)?
17
votes
3answers
8k views

What are the risks of self signing a certificate for SSL

Let's say I sign a SSL certificate for myself, and I'm not using a certified CA. What are the risks and/or threats of doing it?
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votes
2answers
483 views

Good resources for learning cryptography and OpenSSL?

I'm a programmer and I'm working on a Single Sign-on project using SAML. I want to do all I can to make this as secure as possible. Since making a secure Single Sign-on/SAML solution requires signing ...