Symmetric Ciphers Online allows you to encrypt or decrypt arbitrary message
using several well known
symmetric encryption algorithms
such as AES, 3DES, or BLOWFISH.
Symmetric ciphers use the same (or very similar from the algorithmic point of
view) keys for both encryption and decryption of a message. They are designed to
be easily computable and able to process even large messages in real time.
Symmetric ciphers are thus convenient for usage by a single entity that knows
the secret key used for the encryption and required for the decryption of its
private data – for example file system encryption algorithms are based on
symmetric ciphers. If symmetric ciphers are to be used for secure communication
between two or more parties problems related to the management of symmetric keys
arise. Such problems can be solved using a
that includes using
Symmetric ciphers are basic blocks of many cryptography systems and are
often used with other cryptography mechanisms that compensate their
Symmetric ciphers can operate either in the
block mode or in the
Some algorithms support both modes, others support only one mode.
In the block mode, the cryptographic algorithm splits the input message into an
array of small fixed-sized blocks and then encrypts or decrypts the blocks
one by one. In the stream mode, every digit (usually one bit) of the input
message is encrypted separately.
In the block mode processing, if the blocks were encrypted completely
independently the encrypted message might be vulnerable to some trivial attacks.
Obviously, if there were two identical blocks encrypted without any additional
context and using the same function and key, the corresponding encrypted blocks
would also be identical. This is why block ciphers are usually used in various
modes of operation.
Operation modes introduce an additional variable into the function that holds
the state of the calculation. The state is changed during the encryption/decryption
process and combined with the content of every block. This approach mitigates the
problems with identical blocks and may also serve for other purposes. The
initialization value of the additional variable is called the
initialization vector. The
differences between block ciphers operating modes are in the way they combine
the state (initialization) vector with the input block and the way the vector
value is changed during the calculation. The stream ciphers hold and change
their internal state by design and usually do not support explicit input vector
values on their input.
Security note: Data are transmitted over the network in an unencrypted form!
Please do not enter any sensitive information into the form above
as we cannot guarantee you that your data won't be compromised.
Using the Input type selection, choose the type of input –
a text string or a file. In case of the text string input, enter your input
into the Input text textarea1,2.
Otherwise, use the "Browse" button to select the input file to upload. Then select the cryptographic function you
want to use in the Function field.
Depending on the selected function the Initialization vector (IV) field is
shown or hidden. Initialization vector is always a sequence of bytes, each byte
has to be represented in hexadecimal form.
Select the operation mode in the Mode field and enter a key in
the Key field. The permitted lengths of keys for particular cryptographic functions
are listed below. If you don't specify a key with permitted length the key is prolonged with
the proper number of null bytes at the end. When the key is changed the prefix of sha1(key) function is
automatically filled in the IV field. You still may change the IV.
The feature is intended only for your convenience.
Finally, click the "Encrypt!" button or the "Decrypt!" button
depending on whether you want the input message to be encrypted or decrypted.
The output message is displayed in a hex view and can also be downloaded as
a binary file. The format of output file is simply a dump of binary data.
The initialization vector is added to the file name for convenience.
Initialization vector lengths (all modes)
16, 24 or 32
128, 192 or 256
1 to 8 bytes
8 to 64
1 to 24
8 to 192
1 to 56
8 to 448
1 to 56
8 to 448
1 to 32
8 to 256
1 to 256
8 to 2048
1 to 32
8 to 256
1 to 32
8 to 256
1 You can use only hexadecimal characters, newlines, tabulators and enter characters if you decrypt a string. 2 Input text has an autodetect feature at your disposal.
The autodetect detects for you if the content of Input text field is in
form of a plain text or a hexadecimal string. You can turn off the feature by
clicking on 'OFF' or by changing current type of input under the Input text
The maximal size of the the text string input is 131,072 characters.
The maximal size of the input file is 2,097,152 bytes. One IP address is allowed to execute Symmetric Ciphers Online no more than 50 times per hour
and no more than 100 times per day.