how to know which encryption algorithm is used [closed] - encryption

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I have an encrypted code and decrypted code how to know the algorithm?
encrypted code of "A" is "bc1M4j2I4u6VaLpUbAB8Y9kTHBs="
encrypted code of "B" is "rk8oHfWl0P88rWNx921cKbbZU+w="
encrypted code of "C" is "MglsLg7/M9hE7m1nVAes4YKJNX0="
I am making an application which must use that algorithm I have only encrypter software that creates the code but I don't know the algorithm.
How do I know the algorithm?

It's a SHA1 base64 hash algorithm
See this Ruby code
require 'digest/sha1'
puts Digest::SHA1.base64digest 'A'
# bc1M4j2I4u6VaLpUbAB8Y9kTHBs=

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Can symmetric cryptography be used for providing digital signatures? [closed]

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I was wondering what the main reason was for symmetric keys not being used in this context?
With a symmetric key, anyone who could check the signature could also forge a signature. For most of the use cases of digital signatures, we want untrusted parties to be able to verify the signature. That requires that the key you use to check that a signature is correct be insufficient to generate a valid signature, and that requires asymmetric cryptography by definition.

Can I attack two rsa encryption knowing they have different encrypted messages and different modulus, yet a common exponent? [closed]

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So yeah, different modulus(n), same exponent(e), different encrypted messages(C). Can I do anything with that to find the original messages(M) ? Thank you !
Sure. You can factor the modulus, altho for real world RSA keys, that's not gonna be very practical.
More seriously, 99% of all RSA keys use 65537 as the exponent. If a common public exponent were a weakness 99% of all RSA applications would be vulnerable.

Key size of SHA512 hashing algorithm [closed]

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What is the key size of the SHA512 hashing algorithm? I know that the final message digest is 512 bits. I would like to know what key size it uses. Thank you very much :)
Hash functions does not use key. It just map any input to one of 2^512 possible values.
What key? There is no key. It's a hashing algorithm, not an encryption algorithm.

Is it possible to use software and hardware encryption together? [closed]

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I'm trying to do Encryption using software and decryption by Hardware(AES-CTR mode algorithm).But facing some issue.software I'm using openssl logic. I tried encryption by sw and Hw with same input but output is differnt :(
Encryption with hardware and software has different output.I guess that is ok. In fact that is how it should be. Normally due to random salting you get different output.
When you do decryption,, decryption should work if both hard ware and software uses same salting mechanism

RSA encryption theory - modulo theory [closed]

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I'm a bit mathematically challenged and have been working on the RSA cipher (good start). I can find the public and private keys and know how to work do modulo operations on a calculator. The problem is that I can't do them when the numbers get to high. For example say I have:
10^541 mod 2923 = C
The numbers involved here become very large and don't display fully on a calculator, if it can even handle the numbers (mine is crap). What I am wondering is if there is a better method to work out the ciphertext or plaintext that will work for largish numbers.
I think http://math.stackexchange.com would be a better place for this question.
But, essentially, don't save the mod for the end. Break the exponentiation up into many smaller operations with mod after each one.

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