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28 lines
1.1 KiB
Markdown
28 lines
1.1 KiB
Markdown
# OpenSSL
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[OpenSSL](https://www.openssl.org) is a software library for secure
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communication over computer networks.
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## Usage
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### Creating a key pair
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As described by [dreikanter](https://gist.github.com/dreikanter/c7e85598664901afae03fedff308736b)
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you can create and save a pretty secure private key to `private.key` with
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`openssl genrsa -aes256 -out private.key 8912`.
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After that run `openssl rsa -in private.key -pubout -out public.key` to save the
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according public key to `public.key`.
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### Encrypting and decrypting files
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[Dreikanter](https://gist.github.com/dreikanter/c7e85598664901afae03fedff308736b)
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describes to encrypt larger files with symmetric encryption and encrypt the key
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of that using asymmetric encryption.
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If however the file is small enough to be encrypted with the public key
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`public.key` directly run
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`openssl rsautl -encrypt -pubin -inkey public.key -in plaintext.txt -out encrypted.txt`
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where `plaintext.txt` is the message to encrypt and `encrypted.txt` is the
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encrypted message.
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You can decrypt the message using the private key `private.key` as follows
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`openssl rsautl -decrypt -inkey private.key -in encrypted.txt -out plaintext.txt`.
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