OpenSSL: Ciphering With Certificates

Just Between Us

After credentials and keys generation, beyond attestation and authentication, we can cipher.

Caveat: Do not use the same keys to cipher and sign / verify.

The sample utility found at: _lab_cipher_with_cert, illustrates the use.

Ciphering

The sample utility shows how ciphering can be done with using digital certificates.

* Use lab_rsa_oaep_cipher.sh for a quick demo view.

$ ./lab_rsa_oaep_cipher.sh
Caveat: RSA public key can encrypt a file less than the key size, hence, it is usually used to cipher symmetric keys, hence, for data > key size, 'error: data too large for key size'
Generating RSA private key, 1024 bit long modulus (2 primes)
........+++++
....................................+++++
e is 65537 (0x010001)
Export public key to: ./public.pem
writing RSA key
=====================================================
file (plaintext in): ./messages/message_plaintext.txt
=====================================================
can you see me now?
=====================================================
file (ciphered out): ./message_ciphered.out
=====================================================
=▒▒▒GD▒▒+▒▒DXM▒9܅_▒▒᾿▒▒▒▒O▒▒OW▒▒▒▒
3>J7ꠛ▒a▒▒_%▒e▒▒_▒v▒▒▒ȅL▒▒p2▒▒?wr▒▒S▒▒▒▒ƻ▒=f▒▒
▒▒2.g▒;޺K
=====================================================
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