man shishi_decrypt_etype (3): API function

SYNOPSIS

#include <shishi.h>

int shishi_decrypt_etype(Shishi * handle, Shishi_key * key, int keyusage, int32_t etype, const char * in, size_t inlen, char ** out, size_t * outlen);

ARGUMENTS

Shishi * handle: shishi handle as allocated by shishi_init().
Shishi_key * key: key to decrypt with.
int keyusage: integer specifying what this key is decrypting.
int32_t etype: integer specifying what cipher to use.
const char * in: input array with data to decrypt.
size_t inlen: size of input array with data to decrypt.
char ** out: output array with newly allocated decrypted data.
size_t * outlen: output variable with size of newly allocated output array.

DESCRIPTION

Decrypts data as per encryption method using specified key. The key actually used is derived using the key usage. If key usage is 0, no key derivation is used. The OUT buffer must be deallocated by the caller. The default IV is used, see shishi_decrypt_iv_etype if you need to alter it. The next IV is lost, see shishi_decrypt_ivupdate_etype if you need it.

Note that DECRYPT(ENCRYPT(data)) does not necessarily yield data exactly. Some encryption types add pad to make the data fit into the block size of the encryption algorithm. Furthermore, the pad is not guaranteed to look in any special way, although existing implementations often pad with the zero byte. This means that you may have to "frame" data, so it is possible to infer the original length after decryption. Compare ASN.1 DER which contains such information.

RETURN VALUE

Returns SHISHI_OK iff successful.

REPORTING BUGS

Report bugs to <[email protected]>.

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