While Encrypting a File with a Password from the Command Line using OpenSSLis very useful in its own right, the real power of the OpenSSL library is itsability to support the use of public key cryptograph for encrypting orvalidating data in an unattended manner (where the password is not required toencrypt) is done with public keys.
Online RSA Key Generator. Key Size 1024 bit. 512 bit; 1024 bit; 2048 bit; 4096 bit Generate New Keys Async. RSA Encryption Test. Text to encrypt: Encrypt / Decrypt. A 1024-bit key will usually be ready instantly, while a 4096-bit key may take up to several minutes. For a faster and more secure method, see Do It Yourself below. CryptoTools.net does not yet have a tool for facilitating the encryption and decryption of data using RSA, but you may Do It Yourself with the instructions below. Do It Yourself. NIST recommends 2048-bit keys for RSA. An RSA key length of 3072 bits should be used if security is required beyond 2030. NIST key management guidelines further suggest that 15360-bit RSA keys are equivalent in strength to 256-bit symmetric keys. Creating a new key pair for authentication. To create a new key pair, select the type of key to generate from the bottom of the screen (using SSH-2 RSA with 2048 bit key size is good for most people; another good well-known alternative is ECDSA). Then click Generate, and start moving the mouse within the Window. Putty uses mouse movements to. In Table 2 of that document, it says 2048-bit RSA keys are roughly equivalent to a Security Strength of 112. Security strength is simply a number associated with the amount of work required to break a cryptographic algorithm.
The Commands to Run
Generate a 2048 bit RSA Key
Rsa 2048 Bit Strength
You can generate a public and private RSA key pair like this:
openssl genrsa -des3 -out private.pem 2048
That generates a 2048-bit RSA key pair, encrypts them with a password you provideand writes them to a file. You need to next extract the public key file. You willuse this, for instance, on your web server to encrypt content so that it canonly be read with the private key.
Export the RSA Public Key to a File
This is a command that is
openssl rsa -in private.pem -outform PEM -pubout -out public.pem
The
-pubout
flag is really important. Be sure to include it.Next open the
public.pem
and ensure that it starts with-----BEGIN PUBLIC KEY-----
. This is how you know that this file is thepublic key of the pair and not a private key.To check the file from the command line you can use the
less
command, like this:less public.pem
Do Not Run This, it Exports the Private Key
A previous version of the post gave this example in error.
openssl rsa -in private.pem -out private_unencrypted.pem -outform PEM
The error is that the
-pubout
was dropped from the end of the command.That changes the meaning of the command from that of exporting the public keyto exporting the private key outside of its encrypted wrapper. Inspecting theoutput file, in this case private_unencrypted.pem
clearly shows that the keyis a RSA private key as it starts with -----BEGIN RSA PRIVATE KEY-----
.Visually Inspect Your Key Files
It is important to visually inspect you private and public key files to makesure that they are what you expect. OpenSSL will clearly explain the nature ofthe key block with a
-----BEGIN RSA PRIVATE KEY-----
or -----BEGIN PUBLIC KEY-----
.You can use less to inspect each of your two files in turn:
less private.pem
to verify that it starts with a-----BEGIN RSA PRIVATE KEY-----
less public.pem
to verify that it starts with a-----BEGIN PUBLIC KEY-----
The next section shows a full example of what each key file should look like.
The Generated Key Files
The generated files are base64-encoded encryption keys in plain text format.If you select a password for your private key, its file will be encrypted withyour password. Be sure to remember this password or the key pair becomes useless.
The private.pem file looks something like this:
The public key, public.pem, file looks like:
Protecting Your Keys
Depending on the nature of the information you will protect, it’s important tokeep the private key backed up and secret. The public key can be distributedanywhere or embedded in your web application scripts, such as in your PHP,Ruby, or other scripts. Again, backup your keys!
Remember, if the key goes away the data encrypted to it is gone. Keeping aprinted copy of the key material in a sealed envelope in a bank safety depositbox is a good way to protect important keys against loss due to fire or harddrive failure.
Oh, and one last thing.
If you, dear reader, were planning any funny business with the private key that I have just published here. Know that they were made especially for this series of blog posts. I do not use them for anything else.
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Theoretically, RSA keys that are 2048 bits long should be good until 2030. If so, isn't it a bit early to start using the 4096-bit keys that have become increasingly available in encryption-enabled applications? It depends.
In case you're curious where we got the idea of 2048-bit keys being safe to use until 2030, check out the NIST Special Publication 800-57 Part1. In Table 2 of that document, it says 2048-bit RSA keys are roughly equivalent to a Security Strength of 112. Security strength is simply a number associated with the amount of work required to break a cryptographic algorithm. Basically, the higher that number, the greater the amount of work required.
We have reproduced a portion of that table below for those who want a quick reference. It implies longer keys are more difficult to break and are hence more secure.
Security Strength | RSA key length |
<= 80 | 1024 |
112 | 2048 |
128 | 3072 |
192 | 7680 |
256 | 15360 |
The same NIST document also has a table (Table 4) that shows the period over which each Security Strength is deemed acceptable. According to that publication, 112 security strength (which corresponds to 2048-bit keys) is considered to be acceptable until 2030. Again, here's a portion of that table for reference.
Security Strength | Through 2030 | 2031 and beyond |
< 112 | Disallowed | Disallowed |
112 | Acceptabe | Disallowed |
128 | Acceptable | Acceptable |
192 | Acceptable | Acceptable |
256 | Acceptable | Acceptable |
Alright. So now we know 2048 bit keys are indeed acceptable until 2030 as per NIST. So where does that put our 4096 bit keys? Incidentally, the document is silent about this particular key length. However, because the two tables indicate that 3072-bit keys (whose security strength is 128) and 7680-bit keys (whose security strength is 192) are good beyond 2030, we can safely say 4096 bit keys (which are somewhere in between) should likewise be considered secure enough then.
![Crack 2048 bit rsa key Crack 2048 bit rsa key](/uploads/1/2/6/0/126088466/846432694.png)
In fact, since 2048-bit keys are supposed to be disallowed after 2030, we know for certain that 4096 bit keys are going to be more suitable in production environments than 2048 keys when that time comes. But since we're still at least a decade away from 2030, it's probably not yet necessary to migrate from 2048 to 4096, right?
So why then are we already seeing options for 4096-bit keys in some security applications?
4096-bit key provided as an option during server key generation on JSCAPE MFT Server v10.2
Well, there could be a couple of reasons. One is simply to make the application future proof. A future proof security solution can mitigate the risk of cyber threats. We know that cyber criminals are always one step ahead of security professionals, so we're not 100% sure 2048-bit keys are going to remain unbreakable before 2030.
But if the more secure 4096 keys are already available and it's just a matter of clicking the 4096 option, what should stop us from doing just that? One factor that needs to be considered is performance. Longer keys take more time to generate and require more CPU and power when used for encrypting and decrypting. So, in the case of file transfer servers, if your physical server is relatively old and has limited computing resources, then 4096-bit keys may impact your server's performance.
Actually, secure file transfer protocols like HTTPS, FTPS, or SFTP normally use RSA keys only during the start of the connection, when they're used in encrypting the symmetric keys. Once you start transmitting the data, it's going to be the symmetric keys that are going to be used in the subsequent encryption processes.
So, the performance hit due to a 4096-bit key will only be felt within a small fraction of the entire file transfer session. Of course, if your server carries out a large number of concurrent file transfers, then the performance hits can add up. But just how significant are these performance hits? That would depend on several factors like your server's CPU, the number of concurrent file transfers, network bandwidth, and so on.
Rsa 2048 Bit Key Generator Software
In other words, the impact on performance would vary from one scenario to another. The best way to determine if the performance hit would be substantial in your particular environment would be to run actual tests.
JSCAPE MFT Server v10.2, which is due for release on December 8, 2017, already supports 4096-bit keys. So if you want to run some tests against it to see if the performance hits are substantial in your specific environment, then you may download an evaluation edition as soon as it's available. We shall update this blog post with a download link once version 10.2 is out.
You can run performance tests against that JSCAPE MFT Server instance using the load testing feature of JSCAPE MFT Monitor. We've written a blog post featuring a rudimentary load testing session involving key lengths some time in the past. To get some ideas from there, read the post: