GetInstance(String) GetInstance(String) Creates a new KeyGenerator instance that provides the specified key algorithm. GetInstance(String, Provider) GetInstance(String, Provider) Creates a new KeyGenerator instance that provides the specified key algorithm from the specified provider. GetInstance(String, String) GetInstance(String, String) Creates a new KeyGenerator instance that provides. This class provides the functionality of a secret (symmetric) key generator. Key generators are constructed using one of the getInstance class methods of this class. KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object. The all-in-one ultimate online toolbox that generates all kind of keys! Every coder needs All Keys Generator in its favorites! It is provided for free and only supported by ads and donations. I assume key is a password the user entered. Do not use that for encryption directly. Brute-Force attacks against (possibly very weak) user passwords are far easier than against a full 128 (or 192, 256) bit key. Just hashing the password to get a key does not do the trick because it does not slow down the brute force by a relevant amount.
So to explain what i need to do in this programme, is to create an AES key and a private and public key using RSA algorithm. I then wanna encrypt a msg with the AES key and then encrypt that AES key with the RSA public key. And in the end decrypt the message with the RSA private key.
I have only managed to encrypt the message with AES , i have also encrypted the AES key with RSA public key but i cant seem to get the decrytion to work, in other words to decrypt that message with the private key. Im not sure how to move forward, im totally stuck.
Any advice? here is the code. Im very new to cryptography
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There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
fred rosenberger wrote:How do you know it doesn't work? What I mean is, do you get a compiler error? a run time error? Does it throw an exception? Does it run to completion, but the data it decrypted doesn't match what was encrypted?
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Oh im sorry, i wasnt clear. Well i get the pop up asi want from JOptionPane message dialog the message encrypted but not decrypted. So what i see is a message saying :: text encrpyted : fuhgudhgug and text decrypted : fhdhgidg
(as an example) . So it doesnt decrypt it with the private key i suspect.
fred rosenberger wrote:How do you know it doesn't work? What I mean is, do you get a compiler error? a run time error? Does it throw an exception? Does it run to completion, but the data it decrypted doesn't match what was encrypted?
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No errors, beautifully smoothly compiling just not decrypting it at all and it has to be decrypted with the RSA private key so im very stuck on what im doing wrong :/
Also breaking up the excessively long line).
Campbell Ritchie wrote:Too difficult for this forum: moving.
Also breaking up the excessively long line).
Sorry, didnt know
Stephan van Hulst wrote:You're encrypting your message using a symmetric key, and then you're never using that encrypted data again. You're only decrypting your symmetric key. You still need to decrypt your message using your decrypted key.
so im only decrypting the AES key not the message and RSA key itself? thanks, need to take a look at it.
Stephan van Hulst wrote:Keep in mind that both AES and RSA may use block ciphers that use an initialization vector, so when you initialize a cipher for decryption, you may need to pass it the IV used by the encrypting cipher.
If RSA is being used to encrypt the AES key then it should use something like PKCS1 padding since that padding introduces a random element. AES used with ECB padding is susceptible to ciphertext forgery and in order to avoid this AES should always be used with one of the feedback modes such as CBC and use a random IV. The random IV does not need to be kept secret and can be passed in the clear along with the AES ciphertext. One approach is to pre-pend the IV to the AES ciphertext. Using this approach one would ship the RSA encrypted AES key followed by the IV followed by the AES cyphertext.
Richard Tookey wrote:
Stephan van Hulst wrote:Keep in mind that both AES and RSA may use block ciphers that use an initialization vector, so when you initialize a cipher for decryption, you may need to pass it the IV used by the encrypting cipher.
If RSA is being used to encrypt the AES key then it should use something like PKCS1 padding since that padding introduces a random element. AES used with ECB padding is susceptible to ciphertext forgery and in order to avoid this AES should always be used with one of the feedback modes such as CBC and use a random IV. The random IV does not need to be kept secret and can be passed in the clear along with the AES ciphertext. One approach is to pre-pend the IV to the AES ciphertext. Using this approach one would ship the RSA encrypted AES key followed by the IV followed by the AES cyphertext.
Thanks for advice you guys.. my issue is atm that i do not know where in my code to re-use the encrypted data in order to decrypt it. I just feel lost and confused. I have used the PKCS1 padding thanks to your advice and im not getting that kind of error any longer. I thought padding error had to do with the fact that i was trying to convert byte to string but maybe thats not correct? In any case right now im trying to figure out how to re-use my encrypted string 'InputText1'. Im starting to think that maybe it is complicated to decrypt a string that is not a pre-defined specific word or sentence like lets say 'Hello world', or does it matter? It worked to encrypt so should work to decrypt as well. Sorry ive been working with this for a while and i just feel dizzy lately :P
Preliminary -
Create the RSA public and private keys. The public key will be used in the encryption section and the private key used in the decryption.
Encryption section -
1) Create a random AES key.
2) Encrypt this AES key with the RSA public key. Write the encrypted key it to the output.
3) Create a random IV for use with AES encryption.
4) Write it to the output.
5) Encrypt your cleartext with AES using the random AES key and random IV. Write the result to the output.
Decryption section -
1) Read the encrypted AES key from the input.
2) Decrypt the encrypted AES key using the RSA private key.
3) Read the IV from the input.
4) Using the exracted AES key and extracted IV decrypt the rest of the input. This is the recovered cleartext.
Note 1 - DataOutputStream and DataInputStream are very useful in reading and writing since they allow you to write a set of bytes as a length followed by the bytes.
Note 2 - Since this is an exercise you can chain the DataOutputStream to a ByteArrayOutptuStream if you don't actually want to save the output to a file. You can then use the content of the ByteArrayInput to a ByteArrayInputStream chained to a DataInputStream for use in decryption.
Note 3 - You can get away with using ECB mode in the AES cipher as long as you use a random AES key. You would then ignore the IV requirement.
Richard Tookey wrote:It is not obvious from your code what you are trying to do except that it must be an assignment since in general one needs two programs; one to encrypt the cleartext to create the ciphertext and the other to decrypt the ciphertext to recover the cleartext. As an exercise one can just use one program but use two sections; one to encrypt and one to decrypt.
Preliminary -
Create the RSA public and private keys. The public key will be used in the encryption section and the private key used in the decryption.
Encryption section -
1) Create a random AES key.
2) Encrypt this AES key with the RSA public key. Write the encrypted key it to the output.
3) Create a random IV for use with AES encryption.
4) Write it to the output.
5) Encrypt your cleartext with AES using the random AES key and random IV. Write the result to the output.
Decryption section -
1) Read the encrypted AES key from the input.
2) Decrypt the encrypted AES key using the RSA private key.
3) Read the IV from the input.
4) Using the exracted AES key and extracted IV decrypt the rest of the input. This is the recovered cleartext.
Note 1 - DataOutputStream and DataInputStream are very useful in reading and writing since they allow you to write a set of bytes as a length followed by the bytes.
Note 2 - Since this is an exercise you can chain the DataOutputStream to a ByteArrayOutptuStream if you don't actually want to save the output to a file. You can then use the content of the ByteArrayInput to a ByteArrayInputStream chained to a DataInputStream for use in decryption.
Note 3 - You can get away with using ECB mode in the AES cipher as long as you use a random AES key. You would then ignore the IV requirement.
Yes thank you. Its an assignment but we were supposed to create two programmes but it was ok dto do just one if we managed to solve it that way but come to think of it i think its better to do two. Thank you for your help. Ive been thinking about outputstream encrypting a file and send it that way but didnt thinnk it was necessary in just one programme but maybe its better. Thanks for your advice and help.
Richard Tookey wrote:3) Create a random IV for use with AES encryption.
It's not necessary to do this explicitly. Cipher will generate an IV automatically for algorithms that require one. Just call getIV() on the cipher, and send that.
Stephan van Hulst wrote:
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory,. Sep 09, 2015 Re: Freeipa-users freeipa cert validation failed, SECERRORUNTRUSTEDISSUER From: Morgan Marodin To: Alexander Bokovoy redhat com. Search for jobs related to Ionic app or hire on the world's largest freelancing marketplace with 14m+ jobs. It's free to sign up and bid on jobs. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share. I'm working on a project to upgrade an existing system that currently uses RC4 to encrypt a payload with a random session key. The session key is then encrypted with asymmetric public key encryption (. Generate ipa session.key ipa.
Richard Tookey wrote:3) Create a random IV for use with AES encryption.
It's not necessary to do this explicitly. Cipher will generate an IV automatically for algorithms that require one. Just call getIV() on the cipher, and send that.
True. I'm just showing how stale I am.
Howdy.
I am having the same issue when doing the Encryp/decrypt with aes/rsa mechanism.
can you please share your sample code of doing it.
thanks in advance.
- marc
- Java Cryptography Tutorial
- Message Digest and MAC
- Keys and Key Store
- Generating Keys
- Digital Signature
- Cipher Text
- Java Cryptography Resources
- Selected Reading
Java provides KeyGenerator class this class is used to generate secret keys and objects of this class are reusable.
To generate keys using the KeyGenerator class follow the steps given below.
Step 1: Create a KeyGenerator object
The KeyGenerator class provides getInstance() method which accepts a String variable representing the required key-generating algorithm and returns a KeyGenerator object that generates secret keys.
Create KeyGenerator object using the getInstance() method as shown below.
Step 2: Create SecureRandom object
The SecureRandom class of the java.Security package provides a strong random number generator which is used to generate random numbers in Java. Instantiate this class as shown below.
Step 3: Initialize the KeyGenerator
The KeyGenerator class provides a method named init() this method accepts the SecureRandom object and initializes the current KeyGenerator.
Initialize the KeyGenerator object created in the previous step using the init() method.
Example
Following example demonstrates the key generation of the secret key using the KeyGenerator class of the javax.crypto package.
Keygenerator.getinstance Aes Generate Key Code
Output
Keygenerator.getinstance Aes Generate Key Download
The above program generates the following output −