Openssl Generate Aes 256 Key

Posted By admin On 15.12.20
encrypt_openssl.txt
For symmetic encryption, you can use the following:
To encrypt:
openssl aes-256-cbc -salt -a -e -in plaintext.txt -out encrypted.txt
To decrypt:
openssl aes-256-cbc -salt -a -d -in encrypted.txt -out plaintext.txt
For Asymmetric encryption you must first generate your private key and extract the public key.
openssl genrsa -aes256 -out private.key 8912
openssl -in private.key -pubout -out public.key
To encrypt:
openssl rsautl -encrypt -pubin -inkey public.key -in plaintext.txt -out encrypted.txt
To decrypt:
openssl rsautl -decrypt -inkey private.key -in encrypted.txt -out plaintext.txt
Source: http://bsdsupport.org/2007/01/q-how-do-i-use-openssl-to-encrypt-files/
You can't directly encrypt a large file using rsautl. instead, do something like the following:
Generate a key using openssl rand, eg. openssl rand 32 -out keyfile
Encrypt the key file using openssl rsautl
Encrypt the data using openssl enc, using the generated key from step 1.
Package the encrypted key file with the encrypted data. the recipient will need to decrypt the key with their private key, then decrypt the data with the resulting key.
Ultimate solution for safe and high secured encode anyone file in OpenSSL and command-line:
You should have ready some X.509 certificate for encrypt files in PEM format.
NOTE: You can generated a X.509 certificate using:
Private key generation (encrypted private key):
openssl genrsa -aes256 -out private.pem 8912
openssl -in private.pem -pubout -out public.pem
With unecrypted private key:
openssl req -x509 -nodes -days 100000 -newkey rsa:8912 -keyout private_key.pem -out certificate.pem
With encrypted private key:
openssl req -x509 -days 100000 -newkey rsa:8912 -keyout private_key.pem -out certificate.pem
With existing encrypted (unecrypted) private key:
openssl req -x509 -new -days 100000 -key private_key.pem -out certificate.pem
To encrypt:
openssl smime -encrypt -binary -aes-256-cbc -in plainfile.zip -out encrypted.zip.enc -outform PEM yourSslCertificate.pem
openssl smime -encrypt -binary -aes-256-cbc -in plainfile.zip -out encrypted.zip.enc -outform DER yourSslCertificate.pem
For text files:
openssl smime -encrypt -aes-256-cbc -in input.txt -out output.txt -outform DER yourSslCertificate.pem
openssl smime -encrypt -aes-256-cbc -in input.txt -out output.txt -outform PEM yourSslCertificate.pem
What is what:
smime - ssl command for S/MIME utility (smime(1))
-encrypt - chosen method for file process
-binary - use safe file process. Normally the input message is converted to 'canonical' format as required by the S/MIME specification, this switch disable it. It is necessary for all binary files (like a images, sounds, ZIP archives).
-aes-256-cbc - chosen cipher AES in 256 bit for encryption (strong). If not specified 40 bit RC2 is used (very weak). (Supported ciphers)
-in plainfile.zip - input file name
-out encrypted.zip.enc - output file name
-outform DER - encode output file as binary. If is not specified, file is encoded by base64 and file size will be increased by 30%.
yourSslCertificate.pem - file name of your certificate's. That should be in PEM format.
That command can very effectively a strongly encrypt any file regardless of its size or format.
To decrypt:
openssl smime -decrypt -binary -in encrypted.zip.enc -inform DER -out decrypted.zip -inkey private.key -passin pass:your_password
openssl smime -decrypt -binary -in encrypted.zip.enc -inform PEM -out decrypted.zip -inkey private.key -passin pass:your_password
For text files:
openssl smime -decrypt -in encrypted_input.txt -inform DER -out decrypted_input.zip -inkey private.key -passin pass:your_password
openssl smime -decrypt -in encrypted_input.txt -inform PEM -out decrypted_input.zip -inkey private.key -passin pass:your_password
What is what:
-inform DER - same as -outform above
-inkey private.key - file name of your private key. That should be in PEM format and can be encrypted by password.
-passin pass:your_password - your password for private key encrypt. (http://www.openssl.org/docs/apps/openssl.html#PASS_PHRASE_ARGUMENTS)
Source: http://stackoverflow.com/questions/7143514/how-to-encrypt-a-large-file-in-openssl-using-public-key

commented Sep 22, 2015

We want to generate a 256-bit key and use Cipher Block Chaining (CBC). The basic command to use is openssl enc plus some options: -P — Print out the salt, key and IV used, then exit. OpenSSL uses AES with SHA1. If you wish to examine better-written source than OpenSSL, have a look at the article C class that interfaces to OpenSSL ciphers. The article includes very simple source code that: allows you to encrypt and decrypt files or strings using the OpenSSL AES-256-CBC cipher and SHA1 digest algorithms.

I guess this:
openssl -in private.key -pubout -out public.key
should look like:
openssl rsa -in private.key -pubout -out public.key

commented Feb 6, 2018

Can we use public key directly with smime commmand for encryption of a large file?

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This post briefly describes how to utilise AES to encrypt and decrypt files with OpenSSL.

AES - Advanced Encryption Standard (also known as Rijndael).

OpenSSL - Cryptography and SSL/TLS Toolkit

We’ll walk through the following steps:

  • Generate an AES key plus Initialization vector (iv) with openssl and
  • how to encode/decode a file with the generated key/iv pair

Generate Aes 256 Key Openssl

Note: AES is a symmetric-key algorithm which means it uses the same key during encryption/decryption.

Generating key/iv pair

We want to generate a 256-bit key and use Cipher Block Chaining (CBC).

The basic command to use is openssl enc plus some options:

  • -P — Print out the salt, key and IV used, then exit
  • -k <secret> or -pass pass:<secret> — to specify the password to use
  • -aes-256-cbc — the cipher name

Note: We decided to use no salt to keep the example simple.

Issue openssl enc --help for more details and options (e.g. other ciphernames, how to specify a salt, …).

Encoding

https://potenttrusted.weebly.com/blog/avertv-302aaacs-driver-for-mac. Let's start with encoding Hello, AES! contained in the text file message.txt:

Openssl Create Aes 256 Key

Decoding

Decoding is almost the same command line - just an additional -d for decrypting:

Note: Beware of the line breaks

Sha1

While working with AES encryption I encountered the situation where the encoder sometimes produces base 64 encoded data with or without line breaks. /linux-generate-pre-shared-key.html.

Openssl Generate Aes 256 Key Loader

Short answer: Yes, use the OpenSSL -A option. Delphi 2015 license key generator.