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Reference Manual of the Crypt Library

Kurt NÝrmark © normark@cs.aau.dk Department of Computer Science, Aalborg University, Denmark.

LAML Source file: lib/crypt.scm

A password crypting library. This is a primitive encrypting based on a fairly elaborate transformation of string to another string. The sheer complexity of the program below adds to the value of the encryption. The main function is: crypt-string. This library requires the general library.

Table of Contents:
1. The main crypting function. 2. Helping functions.

Alphabetic index:
calculate-exchange-position (calculate-exchange-position n m permutation-vector) Return a number between n and m (actually m - 1), calculated by means of permutation-vector n < m
crypt-string (crypt-string input-password) A poor mans password crypting function.
extend-string (extend-string str extension) Extend string st by extension by means of string merging.
permute-string (permute-string str permutation-vector) Return a permuation of the string carried out determinitically by means of permutation-vector The second parameter, permutation-vector, is a vector of positive integers
shift-up-and-down (shift-up-and-down str shift-vector) Shift the characters in the string str up and down by means of a shift-vector.


1 The main crypting function.
The main crypting function is crypt-string below.

crypt-string
Form (crypt-string input-password)
Description A poor mans password crypting function. The one and only external function of this library. This cryptation will immediately be broken by experts! However, it is better than nothing in practical situations.


2 Helping functions.
This section contains a few helping functions which may be of some use in other situations.

extend-string
Form (extend-string str extension)
Description Extend string st by extension by means of string merging.

permute-string
Form (permute-string str permutation-vector)
Description Return a permuation of the string carried out determinitically by means of permutation-vector The second parameter, permutation-vector, is a vector of positive integers

calculate-exchange-position
Form (calculate-exchange-position n m permutation-vector)
Description Return a number between n and m (actually m - 1), calculated by means of permutation-vector n < m

shift-up-and-down
Form (shift-up-and-down str shift-vector)
Description Shift the characters in the string str up and down by means of a shift-vector. A shift-vector is a vector of integers.

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