Member Avatar for beatle555

I Want A Program For
Cryptography Rsa And Md5 Algorithms
Pls Help Me!!

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  • Latest Post Latest Post by ~s.o.s~

Dani AI

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Quick reality check for (and anyone reopening this old thread): RSA and MD5 are different tools. RSA is an asymmetric cipher built on modular arithmetic and large integers (key generation, modular exponentiation, modular inverse). MD5 is a hashing algorithm that has known collision weaknesses and should not be used for security-sensitive integrity or signing. As and noted, understanding the math and language basics first makes implementation work and debugging far easier.

A practical, safe learning path that addresses the gaps in the thread:

  • Start with modular arithmetic: implement gcd, extended Euclid for modinv, and a fast powmod (square-and-multiply). Test these on small integers and toy primes.
  • Build a toy RSA (very small primes) to verify concept and workflow.
  • Replace hand-made integers with a big-integer library for real sizes — ’s pointer to libraries is on track; consider GMP or OpenSSL BIGNUM (or NTL for research/learning).
  • Add proper message handling: padding (OAEP/PKCS#1) and clear rules for encoding messages into integers.

Example pseudocode (conceptual):

# keygen
p = random_prime()
q = random_prime()
n = p * q
phi = (p-1)*(q-1)
e = choose_coprime(phi)    # common choice: 65537
d = modinv(e, phi)

# encrypt: c = powmod(m, e, n)
# decrypt: m = powmod(c, d, n)

Cautions and troubleshooting: never use raw RSA without padding; don’t use MD5 for signatures or password storage (use SHA-256/SHA-3 and Argon2/bcrypt for passwords); common bugs are message ≥ n, wrong byte-order, integer overflow when not using big-int, and incorrect modular inverse. For production, prefer well-tested libraries (OpenSSL, libgcrypt, libsodium where applicable) rather than a home-rolled crypto stack. If further help is needed, a clear minimal code attempt and exact error/output will make focused guidance possible — the community responders (, , , ) will be able to provide better pointers with that.

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Member Avatar for Grunt

I Want that beatle555 should
first show some efforts before asking help in forums.
Pls Help Yourself!!

commented: Salem agrees +2
Member Avatar for beatle555

I Want that beatle555 should
first show some efforts before asking help in forums.
Pls Help Yourself!!

SO YOU WILL NOT HELP NEWBIES:sad:

Member Avatar for Grunt

SO YOU WILL NOT HELP NEWBIES:sad:

NEWBIES SHOULD NOT BE LOOKING FOR SUCH COMPLEX PROGRAMS. THEY SHOULD RATHER CONCENTRATE ON BASICS OF CRYPYOGRAPHY AND LANGUAGE IN WHICH THEY WANT TO IMPLEMENT THE PROGRAM:!:

Member Avatar for Infarction

SO YOU WILL NOT HELP NEWBIES:sad:

We will help newbies who show some effort, through code or otherwise. We will not write code for newbies. We will not do research for newbies. And, as Grunt pointed out, if you really are a newbie, you probably should not be expecting to write anything complicated yet...

Member Avatar for gw3

Hi,

if you want to see what RSA like cryptography means and needs, please have a look into the NTL library ;)(available also as WinNTL under Windows, download it here: www.shoup.net/ntl/download.html).
You can use this library in your C programs and build your own RSA.
But don't expect that your first implementation will be really secure :-))

But the library itself is famous and widely used among researchers.

Kind regards,
gw3

Member Avatar for ~s.o.s~

Tsk tsk... nowadays everyone wants to be a shaman, resurrecting dead threads......

Thread closed.

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