OpenSSL in Linux is the easiest way to decrypt an encrypted private key. Use the following command to decrypt an encrypted RSA key: openssl rsa -in ssl.key.secure-out ssl.key. Make sure to replace the “server.key.secure” with the filename of your encrypted key, and “server.key” with the file name that you want for your encrypted output. See RSA Calculator for help in selecting appropriate values of N, e, and d. Enter decryption key d and encrypted message C in the table on the right, then click.
This is a little tool I wrote a little while ago during a course that explained how RSA works. The course wasn't just theoretical, but we also needed to decrypt simple RSA messages. Given that I don't like repetitive tasks, my decision to automate the decryption was quickly made. Feel free to take a look at the code to see how it works.
With this tool you'll be able to calculate primes, encrypt and decrypt message(s) using the RSA algorithm.
Currently all the primes between 0 and 0 are stored in a bunch of javascript files, so those can be used to encrypt or decrypt (after they are dynamically loaded). In case this isn't sufficient, you can generate additional primes, which will be preserved until the page reloads.
If you encounter any issues or have suggestions/improvements, please create a new issue on the GitHub project page.
If you are interested in my personal site, you can visit it on canihavesome.cofffee.
Acknowledgments
I haven't written every line of code that's being used to show and generate this tool myself. I'd like to thank:
- Matthew Crumley and other contributors for the BigInteger js library
- Kyle Simpson for the LABjs library
RSA Decoder
Currently RSA decryption is unavailable. However, the following dCode tools can be used to decrypt RSA semi-manually.
Multiplication in order to find p*q and (p-1)(q-1)
Modular Exponentiation A^B mod N
Go to:Modular Exponentiation
ModularInverse e^-1 mod ϕ(N)
Prime Number Generation
Go to:Prime Numbers Search — Coprimes
Tool to decrypt/encrypt with RSA cipher. RSA is an asymetric algorithm for public key cryptography created by Ron Rivest, Adi Shamir and Len Adleman. It is the most used in data exchange over the Internet.
Answers to Questions
How to encrypt using RSA cipher?
RSA encryption is purely mathematical, any message must first be encoded by integers (any encoding works: ASCII, Unicode, or even A1Z26). For RSA encryption, the numbers $ n $ and $ e $ are called public keys.
The (numeric) message is decomposed into numbers (less than $ n $), for each number M the encrypted (numeric) message C is $$ C equiv M^{e}{pmod {n}} $$
Example: Encrypt the message R,S,A (encoded 82,83,65) with the public key $ n = 1022117 $ and $ e = 101 $ that is $ C = 828365^{101} mod 1022117 = 436837 $, 436837 is the encrypted message.
How to generate RSA keys?
![Rsa calculator find e Rsa calculator find e](https://i.stack.imgur.com/4rVwd.jpg)
RSA needs a public key (consisting of 2 numbers $ (n, e) $) and a private key (only 1 number $ d $).
- Select 2 distinct prime numbers $ p $ and $ q $ (the larger they are and the stronger the encryption will be)
- Calculate $ n = p times q $
- Calculate the indicator of Euler $ phi(n) = (p-1)(q-1) $
- Select an integer $ e in mathbb{N} $, prime with $ phi (n) $ such that $ e < phi(n) $
- Calculate the modular inverse $ d in mathbb{N} $, ie. $ d equiv e^{-1} mod phi(n) $ (via the gcd'>extended Euclidean algorithm)
![Decrypt rsa private key online Decrypt rsa private key online](/uploads/1/2/5/7/125716161/585291630.jpg)
With these numbers, the pair $ (n, e) $ is called the public key and the number $ d $ is the private key.
Example: $ p = 1009 $ and $ q = 1013 $ so $ n = pq = 1022117 $ and $ phi(n) = 1020096 $. The numbers $ e = 101 $ and $ phi(n) $ are prime between them and $ d = 767597 $.
The keys are renewed regularly to avoid any risk of disclosure of the private key.
How to decrypt a RSA cipher?
Decryption requires knowing the private key $ d $ and the public key $ n $. For any (numeric) encrypted message C, the plain (numeric) message M is computed: $$ M equiv C^{d}{pmod {n}} $$
Example: Decrypt the message C=436837 with the public key $ n = 1022117 $ and the private key $ d = 767597 $, that is $ M = 436837^{767597} mod 1022117 = 828365 $, 82,83,65 is the plain message (ie. the letters R,S,A)
How to recognize RSA ciphertext?
The message is fully numeric and is normally accompanied by at least one key (also numeric). In practice the keys are displayed in hexadecimal, their length depends on the complexity of the RSA implemented (256 bits, 512, 1024 or 2048 are common)
How to decrypt RSA without the private key?
To find the private key, a hacker must be able to realize the prime factor decomposition of the number $ n $ to find its 2 factors $ p $ and $ q $. For small values (up to a million or a billion), it's quite fast with current algorithms and computers, but beyond that, when the numbers $ p $ and $ q $ have several hundred digits, the decomposition requires on average several hundreds or thousands of years of calculation.
With the numbers $ p $ and $ q $ the private key $ d $ can be computed and the messages can be decrypted.
When RSA have been invented ?
Ronald Rivest, Adi Shamir and Leonard Adleman described the algorithm in 1977 and then patented it in 1983.
Source code
dCode retains ownership of the source code of the script RSA Cipher online. Except explicit open source licence (indicated Creative Commons / free), any algorithm, applet, snippet, software (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any function (convert, solve, decrypt, encrypt, decipher, cipher, decode, code, translate) written in any informatic langauge (PHP, Java, C#, Python, Javascript, Matlab, etc.) which dCode owns rights will not be released for free. To download the online RSA Cipher script for offline use on PC, iPhone or Android, ask for price quote on contact page !