DES_CRYPT

Section: C Library Functions (3)
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NAME

des_crypt , ecb_crypt , cbc_crypt , des_setparity - fast DES encryption

SYNOPSIS

In rpc/des_crypt.h Ft int Fn ecb_crypt char *key char *data unsigned datalen unsigned mode Ft int Fn cbc_crypt char *key char *data unsigned datalen unsigned mode char *ivec Ft void Fn des_setparity char *key

DESCRIPTION

The Fn ecb_crypt and Fn cbc_crypt functions implement the NBS DES (Data Encryption Standard). These routines are faster and more general purpose than crypt(3). They also are able to utilize DES hardware if it is available. The Fn ecb_crypt function encrypts in ECB (Electronic Code Book) mode, which encrypts blocks of data independently. The Fn cbc_crypt function encrypts in CBC (Cipher Block Chaining) mode, which chains together successive blocks. CBC mode protects against insertions, deletions and substitutions of blocks. Also, regularities in the clear text will not appear in the cipher text.

Here is how to use these routines. The first argument, Fa key , is the 8-byte encryption key with parity. To set the key's parity, which for DES is in the low bit of each byte, use Fn des_setparity . The second argument, Fa data , contains the data to be encrypted or decrypted. The third argument, Fa datalen , is the length in bytes of Fa data , which must be a multiple of 8. The fourth argument, Fa mode , is formed by OR 'ing together some things. For the encryption direction OR in either DES_ENCRYPT or DES_DECRYPT For software versus hardware encryption, OR in either DES_HW or DES_SW If DES_HW is specified, and there is no hardware, then the encryption is performed in software and the routine returns Er DESERR_NOHWDEVICE . For Fn cbc_crypt , the Fa ivec argument is the 8-byte initialization vector for the chaining. It is updated to the next initialization vector upon return.

ERRORS

Bq Er DESERR_NONE: No error.
Bq Er DESERR_NOHWDEVICE: Encryption succeeded, but done in software instead of the requested hardware.
Bq Er DESERR_HWERR: An error occurred in the hardware or driver.
Bq Er DESERR_BADPARAM: Bad argument to routine.

Given a result status stat the macro Fn DES_FAILED stat is false only for the first two statuses.

AVAILABILITY

The Fn ecb_crypt , Fn cbc_crypt , and Fn des_setparity functions are part of libtirpc.

RESTRICTIONS

These routines are not available in RPCSRC 4.0. This information is provided to describe the DES interface expected by Secure RPC.