OPENSSL CIPHERS HOW TO
OPENSSL CIPHERS PASSWORD

Before decryption can be performed, the output must be decoded from its Base64 representation. This resulted in a Base64 encoding of the output which is important if you wish to process the cipher with a text editor or read it into a string. When the plaintext was encrypted, we specified -base64.

OPENSSL CIPHERS PASSWORD

There are four steps involved when decrypting: 1) Decoding the input (from Base64), 2) extracting the Salt, 3) creating the key (key-stretching) using the password and the Salt, and 4) performing the AES decryption. Unlike the command line, each step must be explicitly performed with the API. To decrypt the output of an AES encryption (aes-256-cbc) we will use the OpenSSL C++ API. The Salt is written as part of the output, and we will read it back in the next section. v Verbose output: For each ciphersuite, list details as provided by SSLCIPHERdescription(3).-V Like -v, but include the official cipher suite values in hex.-tls12 In combination with the -s option, list the ciphers which would be used if TLSv1.2 were negotiated. This is because a different (random) salt is used. This will result in a different output each time it is run. $ openssl enc -aes-256-cbc -in plaintext.txt -base64 -md sha1 We will use the password 12345 in this example. SHA1 will be used as the key-derivation function. The output will be written to standard out (the console). The following command will prompt you for a password, encrypt a file called plaintext.txt and Base64 encode the output. To encrypt a plaintext using AES with OpenSSL, the enc command is used. Command line OpenSSL uses a rather simplistic method for computing the cryptographic key from a password, which we will need to mimic using the C++ API. OpenSSL uses a hash of the password and a random 64bit salt. Key stretching uses a key-derivation function. Because humans cannot easily remember long random strings, key stretching is performed to create a long, fixed-length key from a short, variable length password. The cryptographic keys used for AES are usually fixed-length (for example, 128 or 256bit keys). The pseudo-commands list-standard-commands, list-message-digest-commands, and list-cipher-commands output a list of all standard commands, message digest commands, or cipher.

OPENSSL CIPHERS HOW TO

In this tutorial we will demonstrate how to encrypt plaintext using the OpenSSL command line and decrypt the cipher using the OpenSSL C++ API. The openssl command line utility has a number of pseudo-commands to provide information on the commands that the version of openssl installed on the system supports. Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. AES ( Advanced Encryption Standard) is a symmetric-key encryption algorithm.

Openssl ciphers