• Encrypting A File With Aes With A Pre Generated Key 2017
• Encrypting A File With Aes With A Pre Generated Key Code
• Encrypting A File With Aes With A Pre Generated Key West
• Encrypting A File With Aes With A Pre Generated Key Number
• Encrypting A File With Aes With A Pre Generated Key West

How could I decrypt a file (encrypted with AES-128) using openssl? I do not remember the passphrase I used to encrypt it, but I saved the key generated and used to encrypt my file. How could I use.

A site like www.ShellScrypt.com uses openssl AES-128 quite intensely to encrypt shell scripts and then makes the encrypted copies of the scripts executable. All you have to do is paste the script to the site, and a zip file will be generated for you. That zip file will contain the encrypted (and executable if it is a script) version of your file. Encrypt the File Using the Generated Key. Now that you have a good random password, you can use that to AES encrypt a file as seen in the 'with passwords' section $ openssl aes-256-cbc -in secret.txt -out secret.txt.enc -pass file:secret.txt.key Decrypting the file works the same way as the 'with passwords' section, except you'll have to pass. Import chilkat # Symmetric encryption algorithms are such that the encryptor and decryptor # share a pre-known secret key. This could be a 'single-use' key that is # derived from a secure key exchange algorithm using RSA, ECC, or Diffie-Hellman, # or it could be a password known to both sides, or # it could simply be the binary bytes of the secret key known in advance on both # sides. An AES key is just some random bytes, of 16, 24 or 32 bytes length - depending of key size, and can in principle be stored in the file system as an binary file. However I do recommend that you put it in a Java Key Store, and protect it by password. You can use the java keytool to do all of this, like this. Apr 15, 2020  Best encryption software for business in 2020: BitLocker, FileVault, Guardium, and more. From on-premise to hybrid environments and the cloud, we have you covered. (CkPython) RSA Encrypt/Decrypt AES Key. Demonstrates how to use RSA to protect a key for AES encryption. It can be used in this scenario: You will provide your RSA public key to any number of counterparts. Your counterpart will generate an AES key, encrypt data (or a file) using it, then encrypt the AES key using your RSA public key.

This guide will demonstrate the steps required to encrypt and decrypt files using OpenSSL on Mac OS X. The working assumption is that by demonstrating how to encrypt a file with your own public key, you'll also be able to encrypt a file you plan to send to somebody else using their private key, though you may wish to use this approach to keep archived data safe from prying eyes.

Too Long, Didn't Read

Assuming you've already done the setup described later in this document, that id_rsa.pub.pcks8 is the public key you want to use, that id_rsa is the private key the recipient will use, and secret.txt is the data you want to transmit…

Encrypting

Encrypting A File With Aes With A Pre Generated Key 2017

Decrypting

Using Passwords

OpenSSL makes it easy to encrypt/decrypt files using a passphrase. Unfortunately, pass phrases are usually 'terrible' and difficult to manage and distribute securely.

To Encrypt a File

You can add -base64 if you expect the context of the text may be subject to being 'visible' to people (e.g., you're printing the message on a pbulic forum). If you do, you'll need to add it to the decoding step as well. You can choose from several cypers but aes-256-cbc is reasonably fast, strong, and widely supported. Base64 will increase the size of the encrypted file by approximately 30%

To Decrypt a File

You will need to provide the same password used to encrypt the file. All that changes between the encrypt and decrypt phases is the input/output file and the addition of the -d flag. If you pass an incorrect password or cypher then an error will be displayed.

Encrypting Files Using your RSA keys

RSA encryption can only work with very short sections of data (e.g. an SHA1 hash of a file, or a password) and cannot be used to encrypt a large file. The solution is to generate a strong random password, use that password to encrypt the file with AES-256 in CBC mode (as above), then encrypt that password with a public RSA key. The encrypted password will only decrypt with a matching public key, and the encrypted file will require the unique password encrypted in the by the RSA key.

Replace OpenSSL

The copy of OpenSSL bundled with Mac OS X has several issues. Mac OS X 10.7 and earlier are not PCI compliant. It is best to replace it. See here for details: http://www.dctrwatson.com/2013/07/how-to-update-openssh-on-mac-os-x/

Generate Your Private/Public Key-pair

By default your private key will be stored in

• ~/.ssh/id_rsa : This is your private key and it must be kept secret
• ~/.ssh/id_rsa.pub : This is your public key, you can share it (for example) with servers as an authorized key for your account.You can change the location of where you store your keys, but this location is typical. Typically you want to ensure the private key is chmod 600, andd the public key is chmod 644.

Generate a PKCS8 Version of Your Public Key

The default format of id_rsa.pub isn't particularly friendly. If you are going to public your key (for example) on your website so that other people can verify the authorship of files attributed to you then you'll want to distribute it in another format. I find it useful to keep a copy in my .ssh folder so I don't have to re-generate it, but you can store it anywhere you like.

Generate a One-Time-Use Password to Encrypt the File

The passwords used to encrypt files should be reasonably long 32+ characters, random, and never used twice. To do this we'll generate a random password which we will use to encrypt the file.

This will generate 192 bytes of random data which we will use as a key. If you think a person may need to view the contents of the key (e.g., they're going to display it on a terminal or copy/paste it between computers) then you should consider base-64 encoding it, however:

1. The password will become approximately 30% longer (and there is a limit to the length of data we can RSA-encrypt using your public key
2. The password will be 'padded' with '=' characters if it's not a multiple of 4 bytes.

A Note on Long Passwords

There is a limit to the maximum length of a message that can be encrypted using RSA public key encryption. If you want to use very long keys then you'll have to split it into several short messages, encrypt them independently, and then concatinate them into a single long string. Decrypting the password will require reversing the technique: splitting the file into smaller chuncks, decrypting them independently, and then concatinating those into the original password key file.

Encrypt the File Using the Generated Key

Now that you have a good random password, you can use that to AES encrypt a file as seen in the 'with passwords' section

Decrypting the file works the same way as the 'with passwords' section, except you'll have to pass the key.

Encrypt the Key Used to Encrypt the File

We used fast symetric encryption with a very strong password to encrypt the file to avoid limitations in how we can use asymetric encryption. Finally, we'll use asymetric encryption to encrypt the password. This solves the problem of 'how do I safely transmit the password for the encrypted file' problem. You can encrypt is using the recipients public key and they can decode it using their private key. Encrypt the password using a public key:

The recipient can decode the password using a matching private key:

Package the Encrypted File and Key

There are a number of ways to do this step, but typically you'll want just a single file you can send to the recipent to make transfer less of a pain. I'd recommend just making a tarball and delivering it through normal methods (email, sftp, dropbox, whatever). Though a secure method of exchange is obviously preferable, if you have to make the data public it should still be resistent to attempts to recover the information.

The file can be extracted in the usual way:

You may want to securely delete the unecrypted keyfile as the recipient will be able to decode it using their private key and you already have the unencrypted data.

posted 4 years agoposted 4 years ago

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors

posted 4 years ago

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?
Help us help you and TellTheDetails.

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.posted 4 years ago

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?
Help us help you and TellTheDetails.

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 :/posted 4 years agoposted 4 years ago

Campbell Ritchie wrote:Too difficult for this forum: moving.
Also breaking up the excessively long line).

Sorry, didnt know posted 4 years agoposted 4 years ago

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. posted 4 years agoposted 4 years ago

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.posted 4 years ago

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 :Pposted 4 years agoposted 4 years ago

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.

Encrypting A File With Aes With A Pre Generated Key Code

posted 4 years ago

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.posted 4 years ago

Stephan van Hulst wrote:

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.

Encrypting A File With Aes With A Pre Generated Key West

Encrypting A File With Aes With A Pre Generated Key Number

posted 2 years ago

Encrypting A File With Aes With A Pre Generated Key West