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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Block size of CTR, CFB and OFB mode of AES in openssl

I am using openssl library. In all documents and webpages it is written that the block size is 128 bites(common for all AES modes). But what I observed in openssl is, for CTR, CFB and OFB modes the ...
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2answers
98 views

Is `arc4random` secure enough?

I need to generate many many initialization vectors and session keys in C++ code. I am wondering if arc4random is up to the task. Last I heard, there are many weaknesses in the RC4 cipher. Should I ...
3
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2answers
3k views

Chrome showing cryptography as 'obsolete'

Similar to this question, Chrome is showing the connection cryptography as obsolete. Opera, IE and Firefox seem perfectly fine with the connection. My guess would be the message authentication is ...
0
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1answer
45 views

Which parameters can I use to analyse my cipher? [closed]

I have made a new methodology for a symmetric key cryptography in which I have used matrix operations, a boolean function and ASCII conversion. Please suggest me the possible parameters to judge my ...
2
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0answers
51 views

Disallowing Similar Passwords [duplicate]

Upfront, I want to clarify that I am not a professional cryptographer, I am more curious about playing with the math and science behind it, and also want to improve my habits with my own personal and ...
3
votes
2answers
133 views

How secure is MD5 for TLS message authentiaction?

I was recently viewing a website and saw its certificate info as follows: Given that MD5 is badly broken and not recommended for hashing, how good is it for use in TLS? And why?
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2answers
230 views

How hash ensure integrity of data? [duplicate]

I understand what a hash is, basically we calculate a hash and append it to the message and send it to the receiver. If someone alters the message, the receiver will know because there would be a ...
0
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1answer
193 views

RSA key sizes v/s public key sizes

I am new to cryptography. I have an api provided by a bank. The banks says that they are using RSA algorithm with 2048 bits. We used this api first to get the public key. Here is the sample public ...
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1answer
45 views

What is the most secure way to protect a custom CMS from infiltration? [closed]

I have a custom CMS with a randomly generated ASCII 100-character string from this site for both my username/password. I also have this following sha512 encryption system, which was created by ...
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2answers
508 views

TrueCrypt vs BitLocker

I would like to ask which one of these TrueCrypt or BitLocker is safer to implement and encrypt the data in a small business environment (Windows 7, 8.1 and Windows Server 2012r) I read about ...
2
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1answer
102 views

difference between public key and host key and security of host key

In SSH, what is the difference between host key and public key. Public key I believe that is part of private/public key pair, so, that anything sent by server(encrypted using private) can be ...
2
votes
2answers
289 views

In theory, can a restricted-use ToR network be created with “Verifiable Encryption”? How should I approach learning it?

I have mobile devices (low power, low bandwidth) need to act as a proxy for certain types of P2P encrypted data, such as voting, bitcoin payment, or other specific-purpose usage, and I want to make ...
2
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1answer
84 views

Why does WPA2 need a 4 way handshake?

If client and AP both have the Pairwise Master Key (PMK) available, why do we need a 4 way handshake again to derive some other key (PTK)? Why can't we use PMK for further security process?
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1answer
108 views

What encryption algorithm does CryptEncrypt in Crypto API use?

I am writing a code to perform encryption and decryption using CryptEncrypt and CryptDecrypt functions, a part of Windows' Crypto API. Can anyone tell me what kind of encryption these two function ...
2
votes
1answer
46 views

Subject verification of certificates

Suppose H has taken C’s certificate and manually changed the subject information in C’s certificate from C to H. Would this modification be detected by A during the certificate verification process?
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1answer
132 views

Crypto Ransomware - How decryption is done when user accept to cooperate?

When you have been "hacked" and you accept to pay for decrypting your encrypted files, how the attacker do the job ? I understood that a symmetric key is used, itself encrypted by the attacker public ...
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1answer
40 views

Is CAST5-CBC as supported by OpenSSL an authenticated encryption method?

I'm looking to encrypt some files using a simple cipher plugin. I have access to using AES-256 in CBC mode, but this doesn't offer message authentication and I'd have to build my own HMAC for it. ...
2
votes
2answers
146 views

Reducing hash output length [duplicate]

I am using output of (keyed) hash function to make sure the input was not modified, I store it along with input. Now output of SHA-1 is 20 bytes. Say I want to reduce the output. And have it output 10 ...
0
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1answer
123 views

Is it dangerous to use the same key (RSA) for both encryption (PGP) and authentication (SSH)?

Alice wants to send an encrypted message to Bob, but she also wants to connect to Carol's server. Are there any dangers associated with using the same RSA key for both PGP and SSH (other than a lack ...
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2answers
185 views

Untraceable Digital Cash?

I have read some articles regarding digital cash that is untraceable (Here). Their protocol is provided below Withdrawal: Alice creates an electronic coin and blinds it. Alice sends the ...
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1answer
33 views

How can i store encryption key into Microsoft provided Key container?

I'm working on an application in which user will enter encryption key via GUI and my app will fetch that encryption key. Now i need to store that received key into Microsoft key container. I got this ...
0
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1answer
44 views

Which stream ciphers are supported in am335x cryptographic accelerator?

I want to use cryptographic accelerator in aes cfb mode [or any other stream cipher]. According to http://e2e.ti.com/support/arm/sitara_arm/f/791/p/156983/658334 link cfb is supported in am335x. I ...
17
votes
4answers
22k views

Google Chrome “Your connection to website is encrypted with obsolete cryptography”

Google Chrome is showing new information in the certificate section. Is this a big deal? If so how can I fix it on the server end? EDIT: Thanks for the answers but I'm not skilled in cryptography ...
16
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4answers
3k views

Is it dangerous to publicly share ciphertext?

Alice wants to share a message with Bob, but Alice and Bob can never be in the same place at the same time. We can assume they both know each others public keys (or agreed on a shared key, if that ...
2
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3answers
237 views

Simple string comparisons not secure against timing attacks [duplicate]

As I learned in a comment for How to encrypt in PHP, properly?, I was told using a string comparison like the following in PHP is susceptible to timing attacks. So it should not be used to compare two ...
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1answer
110 views

How can I tell if my client has been infected with CryptoWall?

Today a client ran a file they believed to be something else, they said a black window appeared, so I checked the code to see what it ran in CMD, but can't quite work out what it's doing. I've just ...
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1answer
126 views

Can you recover the password from ZipCrypto encrypted ZIP file?

I know that "legacy ZIP-crypto" is not secure and you can get at the contents of the file quite easily. Now the question is, can you also get at the password (assume this is a very long, very high ...
2
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1answer
213 views

Does OpenSSH use export ciphers?

With all of this talk of 'FREAK', no one has mentioned OpenSSH. It implements libraries from OpenSSL (until recently, anyway). Why aren't people talking about this? is there even a way to configure ...
7
votes
4answers
358 views

How to check randomness of random number generators?

Assume that I have a smart card that returns an 8 byte (for example) random value on reception of a command. The question is that: How I can check if this value is really random? (I don't have any ...
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1answer
91 views

How to keep a reasonable level of entropy in an encrypted file?

Encrypted (or random) data, by nature exhibit a high entropy value and non unencrypted data will exhibit a low entropy value. From an attacker point of view the precense of this high entropy value in ...
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1answer
42 views

ssl+symmetric with my own encryption algorithm? [closed]

I am a final year student currently doing my project, the title is "Mitigating man in the middle attacks using ssl+symmetric key algorithm". I would like to create my own encryption algorithm. I need ...
3
votes
2answers
318 views

Can this modified 'Many' Time Pad be made 'stronger' by using an extrememly long key?

Starting with a one time pad say you want to encrypt some small strings like the words in this sentence but you want to reuse the same OTP key for each string so that when you encounter the same word ...
1
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1answer
49 views

Using a Cryptovariable with an API Designed for Human-Generated Passwords

I'm working with a vendor who provides an API with a user registration method clearly designed for human-generated passwords. We're calling the API in an offline server-to-server fashion, however, ...
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1answer
30 views

combining imperfect random number generators for shuffling an array

Shuffling an array to create a random stream for encryption is well known. The weakness is in the security of the random number generator that performs the shuffling. But is it true or likely that the ...
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votes
1answer
45 views

Do we need to same PGP version for decryption [closed]

Requirement: In our company Location A uses PGP encryption and sending data over internet. In Location B, we have to decrypt the file. Question is what do we require in Location B Do we need to ...
3
votes
1answer
78 views

Does PKCS #7 (CMS) add assurance to an email if a CRL/OCSP response is included, then revoked?

Suppose I issue a signing certificate in January, and have a daily CRL issued (expires in 1 day) to verify the validity of that signature. Then sometime in July I need to revoke that certificate. My ...
2
votes
1answer
72 views

Is TLS enough to prevent eavesdropping? [duplicate]

Is it enough to use only SSL/TLS for client-server application with authentication, registration and data transmission (like chat)? If it is not what I also need to use?
3
votes
1answer
113 views

Security of hybrid encryption scheme

I want to use a hybrid encryption scheme for file encryption. The scheme must use PKCS#1 v1.5 – which is vulerable to padding oracle attacks – because many smartcards (e.g. the OpenPGP Card) only ...
3
votes
1answer
298 views

SIM card - Cryptography

I would like to have general infos about crypto and commom SIM card in mobile phone(I know there may be different implementations, technos according to the operator...). Is crypto used only for ...
3
votes
1answer
139 views

Has the security of PuTTY been examined?

I am wondering how PuTTY stacks up against other SSH implementations with respect to scrutiny and security of its SSH2 protocol implementation. PuTTY is probably the most-used SSH client on the ...
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votes
1answer
70 views

Tell type of encryption if given both input and output strings [closed]

I have the string Thisisatest that is encoded as MDQ4MGFhMzRhYTNkYjM1OGIzN2NkZTJhYjZiNjUzMjY= and I am trying to find out what encryption is used here. I think that the encoded string is base64 ...
0
votes
1answer
78 views

What is the security/copy protection model for streaming media services?

I realize this is a broad question, but maybe there is a simple answer From my understanding, Streaming media services such as Amazon instant video, Netflix, and others do all decryption client side. ...
1
vote
1answer
67 views

Why should I have my GPG key expire? [duplicate]

When creating a key pair using gpg it asks me for an expiration date: $ gpg --gen-key Please specify how long the key should be valid. 0 = key does not expire <n> = key expires ...
1
vote
2answers
68 views

Two-way encryption that can be nested?

In building a security system, I'm looking to prevent 'man-in-the-middle' attacks in a two-way encryption system, using the following setup: A sends B a message, encrypted with code 1 B sends it ...
7
votes
4answers
948 views

What happens when encrypting with private key? [duplicate]

I have a theoretical question. There is a public key-system. Person1 wants to privately send a message to person2. From my understanding, person1 is supposed to encrypt their message with public key. ...
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0answers
73 views

Questions about SRP algorithm

I trying to use SRP algorithm but I have some questions: Is that a good choice to use for registration and authorization SRP algorithm with SSL/TLS? And for all other transmission using just ...
2
votes
1answer
54 views

What does a FIPS validation certificate cover? Just software version or OS and hardware too?

As I understand it, if you want to be FIPS-compliant you have to use FIPS-certified components. My question is how different can your use of the component by from what's on the component's validation ...
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2answers
126 views

Why use anything other than RSA for transmission encryption?

Being fairly new to the cryptography and data security space, I have sampled a few "Introduction to cryptography" sites/textbooks and they all seem to start in the same general way: This is a Caesar ...
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1answer
63 views

Default Encryption - A Panacea or Placebo

I wrote this on LinkedIn - Discrete Discretion My first question is: Is it accurate to say that default encryption is a placebo? Will default decryption only make end-users think they are secure ...
2
votes
2answers
100 views

How can I create my own public certificate using openssl?

I have a public key/private key pair i generated using two primes p and q. I now need to use openssl to sign and create the certificate. I heard req utility and wrote this from the man pages. openssl ...