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Java/ciphers/ColumnarTranspositionCipher.java at master · iDev-git/Java · GitHub
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ciphers
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ColumnarTranspositionCipher.java
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package
ciphers
;
/**
* Columnar Transposition Cipher Encryption and Decryption.
*
* @author <a href="https://github.com/freitzzz">freitzzz</a>
*/
public
class
ColumnarTranspositionCipher
{
private
static
String
keyword
;
private
static
Object
[][]
table
;
private
static
String
abecedarium
;
public
static
final
String
ABECEDARIUM
=
"abcdefghijklmnopqrstuvwxyzABCDEFG"
+
"HIJKLMNOPQRSTUVWXYZ0123456789,.;:-@"
;
private
static
final
String
ENCRYPTION_FIELD
=
"≈"
;
private
static
final
char
ENCRYPTION_FIELD_CHAR
=
'≈'
;
/**
* Encrypts a certain String with the Columnar Transposition Cipher Rule
*
* @param word Word being encrypted
* @param keyword String with keyword being used
* @return a String with the word encrypted by the Columnar Transposition Cipher Rule
*/
public
static
String
encrpyter
(
String
word
,
String
keyword
) {
ColumnarTranspositionCipher
.
keyword
=
keyword
;
abecedariumBuilder
(
500
);
table
=
tableBuilder
(
word
);
Object
[][]
sortedTable
=
sortTable
(
table
);
String
wordEncrypted
=
""
;
for
(
int
i
=
0
;
i
<
sortedTable
[
i
].
length
;
i
++) {
for
(
int
j
=
1
;
j
<
sortedTable
.
length
;
j
++) {
wordEncrypted
+=
sortedTable
[
j
][
i
];
}
}
return
wordEncrypted
;
}
/**
* Encrypts a certain String with the Columnar Transposition Cipher Rule
*
* @param word Word being encrypted
* @param keyword String with keyword being used
* @param abecedarium String with the abecedarium being used. null for default one
* @return a String with the word encrypted by the Columnar Transposition Cipher Rule
*/
public
static
String
encrpyter
(
String
word
,
String
keyword
,
String
abecedarium
) {
ColumnarTranspositionCipher
.
keyword
=
keyword
;
if
(
abecedarium
!=
null
) {
ColumnarTranspositionCipher
.
abecedarium
=
abecedarium
;
}
else
{
ColumnarTranspositionCipher
.
abecedarium
=
ABECEDARIUM
;
}
table
=
tableBuilder
(
word
);
Object
[][]
sortedTable
=
sortTable
(
table
);
String
wordEncrypted
=
""
;
for
(
int
i
=
0
;
i
<
sortedTable
[
0
].
length
;
i
++) {
for
(
int
j
=
1
;
j
<
sortedTable
.
length
;
j
++) {
wordEncrypted
+=
sortedTable
[
j
][
i
];
}
}
return
wordEncrypted
;
}
/**
* Decrypts a certain encrypted String with the Columnar Transposition Cipher Rule
*
* @return a String decrypted with the word encrypted by the Columnar Transposition Cipher Rule
*/
public
static
String
decrypter
() {
String
wordDecrypted
=
""
;
for
(
int
i
=
1
;
i
<
table
.
length
;
i
++) {
for
(
Object
item
:
table
[
i
]) {
wordDecrypted
+=
item
;
}
}
return
wordDecrypted
.
replaceAll
(
ENCRYPTION_FIELD
,
""
);
}
/**
* Builds a table with the word to be encrypted in rows by the Columnar Transposition Cipher Rule
*
* @return An Object[][] with the word to be encrypted filled in rows and columns
*/
private
static
Object
[][]
tableBuilder
(
String
word
) {
Object
[][]
table
=
new
Object
[
numberOfRows
(
word
) +
1
][
keyword
.
length
()];
char
[]
wordInChards
=
word
.
toCharArray
();
// Fils in the respective numbers
table
[
0
] =
findElements
();
int
charElement
=
0
;
for
(
int
i
=
1
;
i
<
table
.
length
;
i
++) {
for
(
int
j
=
0
;
j
<
table
[
i
].
length
;
j
++) {
if
(
charElement
<
wordInChards
.
length
) {
table
[
i
][
j
] =
wordInChards
[
charElement
];
charElement
++;
}
else
{
table
[
i
][
j
] =
ENCRYPTION_FIELD_CHAR
;
}
}
}
return
table
;
}
/**
* Determines the number of rows the table should have regarding the Columnar Transposition Cipher
* Rule
*
* @return an int with the number of rows that the table should have in order to respect the
* Columnar Transposition Cipher Rule.
*/
private
static
int
numberOfRows
(
String
word
) {
if
(
word
.
length
() /
keyword
.
length
() >
word
.
length
() /
keyword
.
length
()) {
return
(
word
.
length
() /
keyword
.
length
()) +
1
;
}
else
{
return
word
.
length
() /
keyword
.
length
();
}
}
/** @return charValues */
private
static
Object
[]
findElements
() {
Object
[]
charValues
=
new
Object
[
keyword
.
length
()];
for
(
int
i
=
0
;
i
<
charValues
.
length
;
i
++) {
int
charValueIndex
=
abecedarium
.
indexOf
(
keyword
.
charAt
(
i
));
charValues
[
i
] =
charValueIndex
> -
1
?
charValueIndex
:
null
;
}
return
charValues
;
}
/**
* @param table
* @return tableSorted
*/
private
static
Object
[][]
sortTable
(
Object
[][]
table
) {
Object
[][]
tableSorted
=
new
Object
[
table
.
length
][
table
[
0
].
length
];
for
(
int
i
=
0
;
i
<
tableSorted
.
length
;
i
++) {
System
.
arraycopy
(
table
[
i
],
0
,
tableSorted
[
i
],
0
,
tableSorted
[
i
].
length
);
}
for
(
int
i
=
0
;
i
<
tableSorted
[
0
].
length
;
i
++) {
for
(
int
j
=
i
+
1
;
j
<
tableSorted
[
0
].
length
;
j
++) {
if
((
int
)
tableSorted
[
0
][
i
] > (
int
)
table
[
0
][
j
]) {
Object
[]
column
=
getColumn
(
tableSorted
,
tableSorted
.
length
,
i
);
switchColumns
(
tableSorted
,
j
,
i
,
column
);
}
}
}
return
tableSorted
;
}
/**
* @param table
* @param rows
* @param column
* @return columnArray
*/
private
static
Object
[]
getColumn
(
Object
[][]
table
,
int
rows
,
int
column
) {
Object
[]
columnArray
=
new
Object
[
rows
];
for
(
int
i
=
0
;
i
<
rows
;
i
++) {
columnArray
[
i
] =
table
[
i
][
column
];
}
return
columnArray
;
}
/**
* @param table
* @param firstColumnIndex
* @param secondColumnIndex
* @param columnToSwitch
*/
private
static
void
switchColumns
(
Object
[][]
table
,
int
firstColumnIndex
,
int
secondColumnIndex
,
Object
[]
columnToSwitch
) {
for
(
int
i
=
0
;
i
<
table
.
length
;
i
++) {
table
[
i
][
secondColumnIndex
] =
table
[
i
][
firstColumnIndex
];
table
[
i
][
firstColumnIndex
] =
columnToSwitch
[
i
];
}
}
/**
* Creates an abecedarium with a specified ascii inded
*
* @param value Number of characters being used based on the ASCII Table
*/
private
static
void
abecedariumBuilder
(
int
value
) {
abecedarium
=
""
;
for
(
int
i
=
0
;
i
<
value
;
i
++) {
abecedarium
+= (
char
)
i
;
}
}
private
static
void
showTable
() {
for
(
Object
[]
table1
:
table
) {
for
(
Object
item
:
table1
) {
System
.
out
.
print
(
item
+
" "
);
}
System
.
out
.
println
();
}
}
public
static
void
main
(
String
[]
args
) {
String
keywordForExample
=
"asd215"
;
String
wordBeingEncrypted
=
"This is a test of the Columnar Transposition Cipher"
;
System
.
out
.
println
(
"### Example of Columnar Transposition Cipher ###
\n
"
);
System
.
out
.
println
(
"Word being encryped ->>> "
+
wordBeingEncrypted
);
System
.
out
.
println
(
"Word encrypted ->>> "
+
ColumnarTranspositionCipher
.
encrpyter
(
wordBeingEncrypted
,
keywordForExample
));
System
.
out
.
println
(
"Word decryped ->>> "
+
ColumnarTranspositionCipher
.
decrypter
());
System
.
out
.
println
(
"
\n
### Encrypted Table ###"
);
showTable
();
}
}
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