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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cayenne.configuration;
/**
* The ROT-13 password encoder passes the text of the database password through a simple
* Caesar cipher to obscure the password text. The ROT-13 cipher only processes letters --
* numbers and symbols are left untouched. ROT-13 is also a symmetrical cipher and
* therefore provides no real encryption since applying the cipher to the encrypted text
* produces the original source text. See the Wikipedia entry on <a
* href="http://en.wikipedia.org/wiki/Rot-13">ROT13</a> for more information on this
* topic.
*
* @since 3.0
*/
public class Rot13PasswordEncoder implements PasswordEncoding {
public String decodePassword(String encodedPassword, String key) {
return rotate(encodedPassword);
}
public String encodePassword(String normalPassword, String key) {
return rotate(normalPassword);
}
/**
* Applies a ROT-13 Caesar cipher to the supplied value. Each letter in the supplied
* value is substituted with a new value rotated by 13 places in the alphabet. See <a
* href="http://en.wikipedia.org/wiki/ROT13">ROT13</a> for more information.
* <p>
* A Unix command to perform a ROT-13 cipher is:
*
* <pre>
* tr "[a-m][n-z][A-M][N-Z]" "[n-z][a-m][N-Z][A-M]"
* </pre>
*
* @param value The text to be rotated.
* @return The rotated text.
*/
public String rotate(String value) {
if (value == null) {
return null;
}
int length = value.length();
StringBuilder result = new StringBuilder();
for (int i = 0; i < length; i++) {
char c = value.charAt(i);
// If c is a letter, rotate it by 13. Numbers/symbols are untouched.
if ((c >= 'a' && c <= 'm') || (c >= 'A' && c <= 'M'))
c += 13; // The first half of the alphabet goes forward 13 letters
else if ((c >= 'n' && c <= 'z') || (c >= 'N' && c <= 'Z'))
c -= 13; // The last half of the alphabet goes backward 13 letters
result.append(c);
}
return result.toString();
}
}