we've got enough people here recommending GPG. Here is a good answer on the number of iterations: Īlso. Iterations have to be a minimum of 10000. Note: Iterations in decryption have to be the same as iterations in encryption. Openssl enc -d -aes-256-cbc -pbkdf2 -iter 20000 -in hello.enc -out hello.out Openssl enc -aes-256-cbc -pbkdf2 -iter 20000 -in hello -out hello.enc -k meow PBKDF2 is recommended for new applications. See Appendix B.1 for further discussion.)
(However, the maximum effective search space for the derived key may be limited by the structure of the underlying The length of the derived key is essentially PBKDF2 applies a pseudorandom function (see Appendix B.1 for anĮxample) to derive keys. PBKDF1 is recommended only for compatibility with existingĪpplications since the keys it produces may not be large enough for PBKDF1 is compatible with the keyĭerivation process in PKCS #5 v1.5. The length of the derived key is boundedīy the length of the hash function output, which is 16 octets for MD2Īnd MD5 and 20 octets for SHA-1. PBKDF1 applies a hash function, which shall be MD2, MD5 or It is very feasible for an attacker to simply brute force the key. To Decrypt: gpg -output un_encrypted.data -decrypt encrypted.dataĭO NOT USE OPENSSL DEFAULT KEY DERIVATION.Ĭurrently the accepted answer makes use of it and it's no longer recommended and secure. To Encrypt: gpg -output encrypted.data -symmetric -cipher-algo AES256 un_encrypted.data To use GPG to do the same you would use the following commands: Though you have specifically asked about OpenSSL you might want to consider using GPG instead for the purpose of encryption based on this article OpenSSL vs GPG for encrypting off-site backups? Moving your encrypted data from one system to another or when To specify this parameter every time to alleviate problems when The default algorithm as of this writing is sha-256. Use the specified digest to create the key from the passphrase.
OPENSSL ENCRYPT FILE PASSWORD
Password is being specified using one of the other options, the Using the -K option, the IV must explicitly be defined. The actual IV to use: this must be represented as a stringĬomprised only of hex digits.
It probably does not make much sense to specify K option will be used and the IV generated from the password
Whenīoth a key and a password are specified, the key given with the IV must additionally be specified using the -iv option. The actual key to use: this must be represented as a stringĬomprised only of hex digits. Which is why it was not used in the "Short Answer" above! Redundant because a salt is used whether you use this or not To use a salt (randomly generated) when encrypting. Only use this if you need to sendĭata in the form of text format via email etc. This will likely increase theįile size for non-text data. Is set then the input data is base64 decoded before being Place the data is base64 encoded after encryption. Read the password from the first line of instead ofīase64 process the data. Plain-text on the command line and will likely be recorded in Not considered secure because your password appears in The password is used to derive the actual key which Usually you can leave this out and you will be prompted for a Only use this if you want to pass the password as an argument. Įxplanation of most useful parameters with regards to your question: -eĮncrypt the input data: this is the default. Your best source of information for openssl enc would probably be: Ĭommand line: openssl enc takes the following form: openssl enc -ciphername Note: You will be prompted for a password when encrypting or decrypt. To Decrypt: openssl enc -d -aes-256-cbc -in encrypted.data -out un_encrypted.data To Encrypt: openssl enc -aes-256-cbc -in un_encrypted.data -out encrypted.data But to answer the question using openssl: You likely want to use gpg instead of openssl so see "Additional Notes" at the end of this answer.
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