59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
#ifndef __CRYPTO_H__
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#define __CRYPTO_H__
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/** Length of key not sufficient. */
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#define E_KEY_TOO_SHORT 1
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/** Key contains illegal characters. */
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#define E_KEY_ILLEGAL_CHAR 2
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/** Message contains illegal characters. */
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#define E_MESSAGE_ILLEGAL_CHAR 3
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/** Cypher text contains illegal characters. */
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#define E_CYPHER_ILLEGAL_CHAR 4
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#define KEY_CHARACTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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#define MESSAGE_CHARACTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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#define CYPHER_CHARACTERS "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
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/**
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* Key used in de- and encryption.
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*/
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typedef struct {
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int type; /* Type of the key. */
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char* chars; /* Key characters. */
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} KEY;
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/**
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* Encrypt the given text and return the encrypted version. The input text
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* may only contain the letters A-Z. No space or other characters are
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* allowed. In case of illegal characters in the text, the function
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* returns E_MESSAGE_ILLEGAL_CHAR. The key must contain a valid character set
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* and have a sufficient length. For XOR encryption only the characters
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* A-Z are valid in the key. The key must have at least a length of 1.
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*
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* @param key Key to be used for the encryption
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* @param input Clear text
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* @param output Encrypted text
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* @return 0 on success, otherwise error code
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*/
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int encrypt(KEY key, const char* input, char* output);
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/**
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* Decrypt the given text and return the decrypted version. The cypher text
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* may only contain the characters defined as output of the encrypt function.
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* For other characters the function will return E_CYPHER_ILLEGAL_CHAR.
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* The key must contain a valid character set
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* and have a sufficient length. For XOR encryption only the characters
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* A-Z are valid in the key. The key must have at least a length of 1.
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*
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* @param key Key to be used for the decryption
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* @param cypherText Cypher text
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* @param output Decrypted text
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* @return 0 on success, otherwise error code
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*/
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int decrypt(KEY key, const char* cypherText, char* output);
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#endif /* __CRYPTO_H__ */
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