Their length depending on the cipher and key size in question. And as there is no password, also all salting options are obsolete. Usually it is derived together with the key form a password. all non-ECB modes) it is then necessary to specify an initialization vector. It also possible to specify the key directly. Since encryption is the default, it is not necessary to use the -e option.
BASE64 DECODE LINUX PASSWORD
OpenSSL will ask for password which is used to derive a key as well the initialization vector. The result will be Base64 encoded and written to. It will encrypt the file cret using the AES-cipher in CBC-mode. Verifying - enter aes-256-cbc encryption password : $ openssl enc -aes256 -base64 -in cret -out The most basic way to encrypt a file is this $ openssl enc -d -base64 -in text.base64 -out ain To decode a file the the decrypt option ( -d) has to be used $ openssl enc -base64 -in ain -out text.base64
Vice versa while decrypting, zlib will be applied first. After a file is encrypted (and maybe base64 encoded) it will be compressed via zlib. z Use this flag to enable zlib-compression. Possible values for arg are pass: password or file: filename, where password is your password and filename file containing the password. pass arg This specifies the password source. If -P is used just these values are printed, no encryption will take place. p, -P Additionally to any encryption tasks, this prints the key, initialization vector and salt value (if used). With -S salt it is possible to explicitly give its value (in hexadecimal). salt, -nosalt, -S salt These options allow to switch salting on or off. It can take one of the values md2, md5, sha or sha1. md messagedigest This specifies the message digest which is used for key derivation. This process is described in PKCS5#5 (RFC-2898). If no key is given OpenSSL will derive it from a password. This is the key directly used by the cipher algorithm. K key This option allows you to set the key used for encryption or decryption. The equivalents are -pass pass: password and -pass file: filename respectively. k password, -kfile filename Both option are used to specify a password or a file containing the password which is used for key derivation. If not explicitly given it will be derived from the password. iv IV This specifies the initialization vector IV as hexadecimal number.
engine id Specify an engine for example to use special hardware. This does not include any sensitive information. It has nothing to do with the cryptographic algorithms in question. You can use these flags just for encoding Base64 without any ciphers involved. This will produce a file with no line breaks at all. To suppress this you can use in addition to -base64 the -A flag. By default the encoded file has a line break every 64 characters. If you want to decode a base64 file it is necessary to use the -d option. a, -A, -base64 These flags tell OpenSSL to apply Base64-encoding before or after the cryptographic operation. In particular it is necessary to give the correct cipher-name as well as -a, -A or -z options. Of course you have to get all the other options right in order for it to function properly. e or -d This specifies whether to encrypt ( -e) or to decrypt ( -d). It will be created or overwritten if it already exists. out filename This specifies the output file. in filename This specifies the input file. Some ciphers also have short names, for example the one just mentioned is also known as aes256. For example AES-256-CBC for AES with key size 256 bits in CBC-mode. The output gives you a list of ciphers with its variations in key size and mode of operation. To get a list of available ciphers you can use the list -cipher-algorithms command You can obtain an incomplete help message by using an invalid option, eg. The basic usage is to specify a ciphername and various options describing the actual task.
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