The ClassicalCiphers.jl package is licensed under the Simplified "2-clause" BSD License:

> Copyright (c) 2016: Smaug123.
>
> Redistribution and use in source and binary forms, with or without
> modification, are permitted provided that the following conditions are
> met:
>
> 1. Redistributions of source code must retain the above copyright
>    notice, this list of conditions and the following disclaimer.
> 2. Redistributions in binary form must reproduce the above copyright
>    notice, this list of conditions and the following disclaimer in the
>    documentation and/or other materials provided with the distribution.
>
> THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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> THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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> OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.