9 API Reference

9.1 ENCFILE

typedef struct ENCFILE_t ENCFILE;

ENCFILE is an opaque handle to an encrypted file, equivalent to stdio's FILE.

9.2 enc_fopen()

ENCFILE *enc_fopen(const char *filename, const char *rwmode, const char *passphrase);

enc_fopen() opens an encrypted file filename, encrypted with passphrase, for reading or writing depending on rwmode. Other than the passphrase parameter, it is equivalent to fopen().

9.3 enc_add_index

int enc_add_index(ENCFILE *ef, const char *indexfile, const char *passphrase, int index_mode);

Adds an "encryption state index" (ENCINDEX) to a file ef which has been opened for reading. After the successfull completion of this call, you can randomly access any location in the file using enc_fseek().

Parameter index_mode determines the source of the encryption state index. If it contains the INDEX_LOAD flag, an attempt will be made to load it from file indexfile, which is assumed to be encrypted with passphrase. If successfull, the enc_add_index will return 0. If index_mode has the INDEX_CREATE bit set, index will be constructed by internally decrypting the whole file ef. Finally, if index_mode has the INDEX_SAVE bit set, the index will be encrypted with passphrase and saved to indexfile file.

INDEX_* flags can be OR-ed, in which case first the INDEX_LOAD flag will be tested, then INDEX_CREATE and finally INDEX_SAVE. A typical use would be:

  enc_add_index(ef, "test.txt.ix", passphrase, INDEX_LOAD | INDEX_CREATE | INDEX_SAVE);

where encio will first attempt to load the index from test.txt.ix and if that fails it will create the index, and store it to test.txt.ix.

9.4 stdio-like functions

int enc_fread(void *out, int size, int count, ENCFILE *ef); int enc_fwrite(void *data, int size, int count, ENCFILE *ef);

int enc_fseek(ENCFILE *ef, long at, int dir); int enc_ftell(ENCFILE *ef);

void enc_fflush(ENCFILE *ef); int enc_feof(ENCFILE *ef); int enc_fclose(ENCFILE *ef);

void enc_info(ENCFILE *ef);

All these functions function exactly like their stdio counterparts.