class type cipher =object..end
method name : stringThe name of the cipher
method mode : stringThe mode of the cipher
method key_lengths : (int * int) listSupported key lengths as pairs min,max. If there is a recommended
key length, this is the first.
method iv_lengths : (int * int) listSupported iv lengths as pairs min,max. If there is a recommended
iv length, this is the first.
method block_constraint : intThe buffers used with encrypt/decrypt must have a length that is a multiple of this number. (In ECB mode this is the block size.)
method supports_aead : boolWhether this cipher integrates authentication
method create : string -> padding -> cipher_ctxcreate c p key: create a new cipher context for key. If not set,
the initialization vector is assumed to be zero, and the header the
empty string.
The cipher context can be used for either encrypting or decrypting a single message.
