I am looking for checksum algorithm written in obj-c so that I can validate a ticket(number) and generate 2Dbar code based on validation.
Any ideas on how to achieve this?
Thanks
Sounds like you can use a public-key cryptographic function.
Encrypt with the private key fixed length information, including a number (the real ticket number) and a random salt (to reduce the chance of someone cracking your key), into a fixed length output.
You can then use the public key to decode that output and verify that the information is there.
Here is some Apple sample code that demonstrates the use of cryptographic functions.
For 2D barcode code, you could start by looking at ZXing
Related
In am using PKCS11Interop in C#, i got CKR_MECHANISM_INVALID error while trying to use method Sign. The key object i am using is of mechanism type CKM_EC_KEY_PAIR_GEN . but at signing time, i use mechanism CKM_ECDSA_SHA512 .
I tried to define key mechanism as CKM_ECDSA_SHA512 at key-pair generation time, but it seems that this key type needs some attributes that i don't know. The attributes i am using is similar to the correct version of this question, but it seems using hash algorithms need some thing more.
Please guide me how should i use SHA512 hash algorithm with ECDSA elliptic key.
Your unmanaged PKCS#11 library most likely does not support CKM_ECDSA_SHA512.
By returning CKR_MECHANISM_INVALID error your unmanaged PKCS#11 library is telling you that "An invalid mechanism was specified to the cryptographic operation". You can use GetMechanismInfo() method to check whether the mechanism is supported:
if (!slot.GetMechanismList().Contains(CKM.CKM_ECDSA_SHA512))
throw new Exception("Unmanaged PKCS#11 library does not support CKM_ECDSA_SHA512 mechanism");
However CKM_ECDSA_SHA512 (hashing and signing) mechanism is used rather rarely. It's much more common and efficient to compute SHA512 hash in your application and then sign it with CKM_ECDSA (just signing) mechanism.
For reference I only know python so that's what I've been working with.
I've recently been looking into making my own hashing algorithm to further my understanding on how they work, I'm not looking into creating the most cryptographically secure hashing algorithm, just something that is a bit more secure than validating passwds in plain-text.(in other words I don't care if this algorithm has copious amounts of collisions.
From what I understand about hash functions is that they use ???? to obfuscate the input password. Where I'm getting caught up is how the function takes a user input, like "password1" and translates that into numbers the system can work with, then, what exact methods do they use to obfuscate them?
Apologies if this is a stupid question but I cant find any material on this that isn't way beyond my understanding or basic enough where they gloss over what happens inside the hash algorithm.
I am searching for a way to encrypt a file via AES using Swift in my Cocoa Applications.
As far as I can see the common frameworks (i.e. CryptoSwift) are supposed to encrypt text only.
Is there a specific framework for this job or is there any kind of macOS built in method for this?
Thanks!
Yes, using CommonCrypto is a good start. I would not recommend using any homegrown implementations however.
Doing security right is hard, AES is no exception to this.
You need to use a proper key of the correct length ( 64 or 32 bytes preferred )
You need to use padding ( I recommend PKCS7 ) in case your data is shorter than the blocksize / keysize. AES is not secure on its own and this bit is important.
You also really want to use an initializationVector, ( either appendend or prepended to the final data stream ) since otherwise it would be possible for an attacker to draw correlations between several encrypted streams from the same key
You should also make use of a HMAC ( SHA2-256 and up, also available in commoncrypto ) in order to prevent tampering with your encrypted data and giving you unexpected and potentially harmful result data.
The list goes on, but my memory fails me at this point since It has been a while since I needed to create an implementation.
I would highly recommend googling around for a standard implementation that wraps around CommonCrypto.
I would also suggest that using anything that is written as is ( I.E. CryptoSwift ) is not recommended as the codebase isn't proven and went through proper vetting like Apple's frameworks are.
I have a NSString like #"123456". I want to convert this string into byte array and then I want to shift some bytes using some arithmetic operations. Then I want to apply SHA256Hash on that and finally want to encrypt a string using the final result. I have tried many approaches but still got no success. I am very confused in this.If someone wants to look at code i'll post the code.
Edit:
My actual goal is to encrypt an string using AES256 encryption algorithm. And I want to generate my own key and I want to pass my own IV.
I assume you're trying achieve some kind of security. On the other hand it does not look like you're very familiar with the tools and methods you're using. This is a bad start.
Security is a very difficult thing to do—even for experienced developers. Maybe there's a way to reuse some existing implementation for your security needs.
My advice would be not to reinvent things, especially when they are as hard and as crucial as security.
Now I want to encrypt or decrypt some data in object-c use DES algorithm ,can somebody give me some suggestion?
First point. AES has replaced DES as the de-facto encrpytion standard, at least for the banking industry.
Second Point: Irrespective of what algo you decide on, this is what you have to do.
Add the Security.framework to your project.
Import the "CommonCrypto/CommonCryptor.h" file. This contains all the interfaces for symmetric encryption.
Using the methods in this class, you can define your encryption algo (AES, DES, etc.), the key size, padding that you want to use, etc.
You have to option of a one-shot API for encryption/decryption (CCCrypt()) or more advanced options if needed.
Hope this helps. Let me know if you need any particular information.
A code sample can be found in How to encrypt an NSString in Objective C with DES in ECB-Mode?
As the referring topic describes, you will have to keep in mind that DES uses a 56-bit (7 bytes) key and 64-bit (8 bytes) blocks.
Although DES is symmetric you will have to decrypt data by providing the kCCDecrypt option to the CCCrypt function.