AES Encryption – Easily encrypt or decrypt strings or files (2024)

• Hash Functions Online
• Online Encoders and Decoders

Symmetric Ciphers Online allows you to encrypt or decrypt arbitrary messageusing several well knownsymmetric encryption algorithmssuch as AES, 3DES, or BLOWFISH.

Symmetric ciphers use the same (or very similar from the algorithmic point ofview) keys for both encryption and decryption of a message. They are designed tobe easily computable and able to process even large messages in real time.Symmetric ciphers are thus convenient for usage by a single entity that knowsthe secret key used for the encryption and required for the decryption of itsprivate data – for example file system encryption algorithms are based onsymmetric ciphers. If symmetric ciphers are to be used for secure communicationbetween two or more parties problems related to the management of symmetric keysarise. Such problems can be solved using ahybrid approachthat includes usingasymmetric ciphers.Symmetric ciphers are basic blocks of many cryptography systems and areoften used with other cryptography mechanisms that compensate theirshortcomings.

Symmetric ciphers can operate either in theblock mode or in thestream mode.Some algorithms support both modes, others support only one mode.In the block mode, the cryptographic algorithm splits the input message into anarray of small fixed-sized blocks and then encrypts or decrypts the blocksone by one. In the stream mode, every digit (usually one bit) of the inputmessage is encrypted separately.

In the block mode processing, if the blocks were encrypted completelyindependently the encrypted message might be vulnerable to some trivial attacks.Obviously, if there were two identical blocks encrypted without any additionalcontext and using the same function and key, the corresponding encrypted blockswould also be identical. This is why block ciphers are usually used in variousmodes of operation.Operation modes introduce an additional variable into the function that holdsthe state of the calculation. The state is changed during the encryption/decryptionprocess and combined with the content of every block. This approach mitigates theproblems with identical blocks and may also serve for other purposes. Theinitialization value of the additional variable is called theinitialization vector. Thedifferences between block ciphers operating modes are in the way they combinethe state (initialization) vector with the input block and the way the vectorvalue is changed during the calculation. The stream ciphers hold and changetheir internal state by design and usually do not support explicit input vectorvalues 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 aboveas 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 inputinto the Input text textarea^1,2.Otherwise, use the "Browse" button to select the input file to upload. Then select the cryptographic function youwant to use in the Function field.Depending on the selected function the Initialization vector (IV) field isshown or hidden. Initialization vector is always a sequence of bytes, each bytehas to be represented in hexadecimal form.

Select the operation mode in the Mode field and enter a key inthe Key field. The permitted lengths of keys for particular cryptographic functionsare listed below. If you don't specify a key with permitted length the key is prolonged withthe proper number of null bytes at the end. When the key is changed the prefix of sha1(key) function isautomatically filled in the IV field. You still may change the IV.The feature is intended only for your convenience. Using the radio buttons under theKey input field, you can specify whether the entered key valueshould be interpreted as a plain text or a hexadecimal value.

Finally, click the "Encrypt!" button or the "Decrypt!" buttondepending 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 asa 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.

Table 1. Supported key lengths and IV lengths
¹ You can use only hexadecimal characters, newlines, tabulators and new line 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 inform of a plain text or a hexadecimal string. You can turn off the feature byclicking on 'OFF' or by changing current type of input under the Input textfield.