The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> encrypt - encoding function (CRYPT)

#### SYNOPSIS

> ``[XSI] #include <unistd.h>
> void encrypt(char` block`[64], int` edflag`);``
> `
> `

#### DESCRIPTION

> The encrypt() function shall provide access to an implementation-defined encoding algorithm. The key generated by setkey() is used to encrypt the string block with encrypt().

> The block argument to encrypt() shall be an array of length 64 bytes containing only the bytes with values of 0 and 1. The array is modified in place to a similar array using the key set by setkey(). If edflag is 0, the argument is encoded. If edflag is 1, the argument may be decoded (see the APPLICATION USAGE section); if the argument is not decoded, errno shall be set to [ENOSYS].

> The encrypt() function shall not change the setting of errno if successful. An application wishing to check for error situations should set errno to 0 before calling encrypt(). If errno is non-zero on return, an error has occurred.

> The encrypt() function need not be thread-safe.

#### RETURN VALUE

> The encrypt() function shall not return a value.

#### ERRORS

> The encrypt() function shall fail if:

> [ENOSYS]
>   The functionality is not supported on this implementation.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> Historical implementations of the encrypt() function used a rather primitive encoding algorithm.

> In some environments, decoding might not be implemented. This is related to some Government restrictions on encryption and decryption routines. Historical practice has been to ship a different version of the encryption library without the decryption feature in the routines supplied. Thus the exported version of encrypt() does encoding but not decoding.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> A future version of the standard may mark this interface as obsolete or remove it altogether.

#### SEE ALSO

> crypt, setkey

> XBD <unistd.h>

#### CHANGE HISTORY

> First released in Issue 1. Derived from Issue 1 of the SVID.

#### Issue 5

> A note indicating that this function need not be reentrant is added to the DESCRIPTION.

#### Issue 6

> In the DESCRIPTION, the note about reentrancy is expanded to cover thread-safety.

#### Issue 7

> Austin Group Interpretation 1003.1-2001 #156 is applied.

> POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0085 [899] is applied.

End of informative text.

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