---
name: "cbc_crypt"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/cbc_crypt"
---

# cbc\_crypt(3)

fast DES encryption

## NAME

**des\_crypt**, **ecb\_crypt**, **cbc\_crypt**, **des\_setparity** – fast DES encryption

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<rpc/des\_crypt.h\>**

*int*\

**ecb\_crypt**(*char \*key*, *char \*data*, *unsigned datalen*, *unsigned mode*);

*int*\

**cbc\_crypt**(*char \*key*, *char \*data*, *unsigned datalen*, *unsigned mode*, *char \*ivec*);

*void*\

**des\_setparity**(*char \*key*);

## DESCRIPTION

The **ecb\_crypt**() and **cbc\_crypt**() functions implement the NBS DES (Data Encryption Standard). These routines are faster and more general purpose than [crypt(3)](/crypt/3.md). They also are able to utilize DES hardware if it is available. The **ecb\_crypt**() function encrypts in ECB (Electronic Code Book) mode, which encrypts blocks of data independently. The **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, *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 **des\_setparity**(). The second argument, *data*, contains the data to be encrypted or decrypted. The third argument, *datalen*, is the length in bytes of *data*, which must be a multiple of 8. The fourth argument, *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 DESERR\_NOHWDEVICE. For **cbc\_crypt**(), the *ivec* argument is the 8-byte initialization vector for the chaining. It is updated to the next initialization vector upon return.

## ERRORS

- \[DESERR\_NONE\]

  No error.

- \[DESERR\_NOHWDEVICE\]

  Encryption succeeded, but done in software instead of the requested hardware.

- \[DESERR\_HWERROR\]

  An error occurred in the hardware or driver.

- \[DESERR\_BADPARAM\]

  Bad argument to routine.

Given a result status *stat*, the macro **DES\_FAILED**(*stat*) is false only for the first two statuses.

## SEE ALSO

[crypt(3)](/crypt/3.md)

## RESTRICTIONS

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