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Vigenère cipher provider

The Vigenère provider only contains one algorithm, which is an adaptation of the well known Vigenère cipher, covering the whole range of byte values, not just alphabetic characters.

This cipher, as well as its history, is described in the Vigenère_cipher wikipedia page

Algorithm Names

The following names can be used with EVP_CIPHER_fetch(3)

  • vigenere
  • 1.3.6.1.4.1.5168.4711.22087.1

Properties

The following property can be used to distinguish this particular implementation of the Vigenère cipher when fetching it with EVP_CIPHER_fetch(3):

  • x.author=@levitte

Parameters

Provider parameters

These parameters can be retrieved using OSSL_PROVIDER_get_params(3):

  • "version" <UTF8 string>

    The version number of the provider.

  • "buildinfo" <UTF8 string>

    The build type as specified by cmake.

  • "author" <UTF8 string>

    An identifier for the author of this provider.

Vigenère cipher parameters

Algorithm parameters

These parameters can be retrieved using EVP_CIPHER_gettable_params(3) and EVP_CIPHER_get_params(3):

  • "blocksize" <unsigned integer>

    The block size of this cipher (it will always be 1).

    The OpenSSL call EVP_CIPHER_block_size(3) uses this parameter implicitly.

  • "keylen" <unsigned integer>

    The standard key length for this cipher, expressed in number of bytes. It's usually 16 (i.e. 128 bits), but may be changed with the environment variable VIGENERE_KEYLEN, further described below.

    The OpenSSL call EVP_CIPHER_key_length(3) uses this parameter implicitly.

Cipher context parameters

This parameters can be retrieved using EVP_CIPHER_CTX_gettable_params(3), EVP_CIPHER_CTX_get_params(3), EVP_CIPHER_CTX_settable_params(3), and EVP_CIPHER_CTX_set_params(3):

  • "keylen" <unsigned integer>

    The key length used in the given cipher context, expressed in number of bytes. It defaults to the standard key length as described above, but may be changed to the user's preference.

    The OpenSSL calls EVP_CIPHER_CTX_set_key_length(3) and EVP_CIPHER_CTX_key_length(3) use this parameter implicitly.

Environment

  • VIGENERE_KEYLEN

    This environment variable can be set to an arbitrary key length, expressed in bytes. The number syntax is implied by strtoul(3), which means that a number starting with "0x" will be understood as a hexadecimal number, and a number starting with "0" will be understood as an octal number.

    This allows the user of openssl enc to specify the desired key length, which is otherwise not supported by that command.

Example command line usage

These examples all assume that vigenere.so / vigenere.dll is located in the current directory.

  • Listing the provider itself:

    $ openssl list -provider-path . -provider vigenere -providers
Providers:
  vigenere
    version: 1.2

  • Listing the algorithm:

    $ openssl list -provider-path . -provider vigenere \
    -cipher-algorithms -verbose
...
Provided:
  { 1.3.6.1.4.1.5168.4711.22087.1, vigenere } @ vigenere
    description: undefined
    retrievable algorithm parameters:
      blocksize: unsigned integer (max 8 bytes large)
      keylen: unsigned integer (max 8 bytes large)
    retrievable operation parameters:
      keylen: unsigned integer (max 8 bytes large)
    settable operation parameters:
      keylen: unsigned integer (max 8 bytes large)

  • Encryption with the standard key length (128 bits, i.e. 16 bytes):

    $ echo "The quick brown fox jumps over the lazy dog" \
  | openssl enc -provider-path . -provider vigenere \
        -e -vigenere \
        -K 00112233445566778899AABBCCDDEEFF \
        -a
VHmHU7XKz9rzuQwtO1RcH2aAmlOuytPn+7kZMTFPDnNodkKfpc/fl+wIEcU=

  • Encryption with the non-standard key length (256 bits, i.e. 32 bytes):

    $ echo "The quick brown fox jumps over the lazy dog" \
  | VIGENERE_KEYLEN=32 openssl enc -provider-path . -provider vigenere \
      -e -vigenere \
      -K 00112233445566778899AABBCCDDEEFF0123456789ABCDEF0123456789ABCDEF \
      -a
VHmHU7XKz9rzuQwtO1RcH2eSvYfzIDpfdEO03e4d7WNodkKfpc/fl+wIEcU=

Disclaimer

This provider is a very small demonstration of fairly minimum requirements for a cipher in an OpenSSL 3.0 provider module.

The cipher that it provides is a toy and should not be used in a real situation.