4.3BSD-Reno/share/man/cat3/des.0
DES_CRYPT(3) 4.0 DES_CRYPT(3)
NNAAMMEE
des_read_password, des_string_to_key, des_random_key,
des_set_key, des_ecb_encrypt, des_cbc_encrypt,
des_pcbc_encrypt, des_cbc_cksum, des_quad_cksum, - (new) DES
encryption
SSYYNNOOPPSSIISS
##iinncclluuddee <<kkeerrbbeerroossIIVV//ddeess..hh>>
iinntt ddeess__rreeaadd__ppaasssswwoorrdd((kkeeyy,,pprroommpptt,,vveerriiffyy))
des_cblock *key;
char *prompt;
int verify;
iinntt ddeess__ssttrriinngg__ttoo__kkeeyy((ssttrr,,kkeeyy))
cchhaarr **ssttrr;;
ddeess__ccbblloocckk kkeeyy;;
iinntt ddeess__rraannddoomm__kkeeyy((kkeeyy))
ddeess__ccbblloocckk **kkeeyy;;
iinntt ddeess__sseett__kkeeyy((kkeeyy,,sscchheedduullee))
ddeess__ccbblloocckk **kkeeyy;;
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
iinntt ddeess__eeccbb__eennccrryypptt((iinnppuutt,,oouuttppuutt,,sscchheedduullee,,eennccrryypptt))
ddeess__ccbblloocckk **iinnppuutt;;
ddeess__ccbblloocckk **oouuttppuutt;;
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
iinntt eennccrryypptt;;
iinntt ddeess__ccbbcc__eennccrryypptt((iinnppuutt,,oouuttppuutt,,lleennggtthh,,sscchheedduullee,,iivveecc,,eennccrryypptt))
ddeess__ccbblloocckk **iinnppuutt;;
ddeess__ccbblloocckk **oouuttppuutt;;
lloonngg lleennggtthh;;
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
ddeess__ccbblloocckk **iivveecc;;
iinntt eennccrryypptt;;
iinntt ddeess__ppccbbcc__eennccrryypptt((iinnppuutt,,oouuttppuutt,,lleennggtthh,,sscchheedduullee,,iivveecc,,eennccrryypptt))
ddeess__ccbblloocckk **iinnppuutt;;
ddeess__ccbblloocckk **oouuttppuutt;;
lloonngg lleennggtthh;;
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
ddeess__ccbblloocckk **iivveecc;;
iinntt eennccrryypptt;;
uunnssiiggnneedd lloonngg ddeess__ccbbcc__cckkssuumm((iinnppuutt,,oouuttppuutt,,lleennggtthh,,sscchheedduullee,,iivveecc))
ddeess__ccbblloocckk **iinnppuutt;;
ddeess__ccbblloocckk **oouuttppuutt;;
lloonngg lleennggtthh;;
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
Printed 7/27/90 Kerberos 1
DES_CRYPT(3) 4.0 DES_CRYPT(3)
ddeess__ccbblloocckk **iivveecc;;
uunnssiiggnneedd lloonngg qquuaadd__cckkssuumm((iinnppuutt,,oouuttppuutt,,lleennggtthh,,oouutt__ccoouunntt,,sseeeedd))
ddeess__ccbblloocckk **iinnppuutt;;
ddeess__ccbblloocckk **oouuttppuutt;;
lloonngg lleennggtthh;;
iinntt oouutt__ccoouunntt;;
ddeess__ccbblloocckk **sseeeedd;;
DDEESSCCRRIIPPTTIIOONN
This library supports various DES encryption related opera-
tions. It differs from the _c_r_y_p_t, _s_e_t_k_e_y, _a_n_d _e_n_c_r_y_p_t
library routines in that it provides a true DES encryption,
without modifying the algorithm, and executes much faster.
For each key that may be simultaneously active, create a
ddeess__kkeeyy__sscchheedduullee struct, defined in "des.h". Next, create
key schedules (from the 8-byte keys) as needed, via
_d_e_s__s_e_t__k_e_y, prior to using the encryption or checksum rou-
tines. Then setup the input and output areas. Make sure to
note the restrictions on lengths being multiples of eight
bytes. Finally, invoke the encryption/decryption routines,
_d_e_s__e_c_b__e_n_c_r_y_p_t or _d_e_s__c_b_c__e_n_c_r_y_p_t or _d_e_s__p_c_b_c__e_n_c_r_y_p_t, or,
to generate a cryptographic checksum, use _q_u_a_d__c_k_s_u_m (fast)
or _d_e_s__c_b_c__c_k_s_u_m (slow).
A _d_e_s__c_b_l_o_c_k struct is an 8 byte block used as the fundamen-
tal unit for DES data and keys, and is defined as:
ttyyppeeddeeff uunnssiiggnneedd cchhaarr ddeess__ccbblloocckk[[88]];;
and a _d_e_s__k_e_y__s_c_h_e_d_u_l_e, is defined as:
ttyyppeeddeeff ssttrruucctt ddeess__kkss__ssttrruucctt {{ddeess__ccbblloocckk __;;}}
ddeess__kkeeyy__sscchheedduullee[[1166]];;
_d_e_s__r_e_a_d__p_a_s_s_w_o_r_d writes the string specified by _p_r_o_m_p_t to
the standard output, turns off echo (if possible) and reads
an input string from standard input until terminated with a
newline. If _v_e_r_i_f_y is non-zero, it prompts and reads input
again, for use in applications such as changing a password;
both versions are compared, and the input is requested
repeatedly until they match. Then _d_e_s__r_e_a_d__p_a_s_s_w_o_r_d con-
verts the input string into a valid DES key, internally
using the _d_e_s__s_t_r_i_n_g__t_o__k_e_y routine. The newly created key
is copied to the area pointed to by the _k_e_y argument.
_d_e_s__r_e_a_d__p_a_s_s_w_o_r_d returns a zero if no errors occurred, or a
-1 indicating that an error occurred trying to manipulate
the terminal echo.
_d_e_s__s_t_r_i_n_g__t_o__k_e_y converts an arbitrary length null-
terminated string to an 8 byte DES key, with odd byte
Printed 7/27/90 Kerberos 2
DES_CRYPT(3) 4.0 DES_CRYPT(3)
parity, per FIPS specification. A one-way function is used
to convert the string to a key, making it very difficult to
reconstruct the string from the key. The _s_t_r argument is a
pointer to the string, and _k_e_y should point to a _d_e_s__c_b_l_o_c_k
supplied by the caller to receive the generated key. No
meaningful value is returned. Void is not used for compati-
bility with other compilers.
_d_e_s__r_a_n_d_o_m__k_e_y generates a random DES encryption key (eight
bytes), set to odd parity per FIPS specifications. This
routine uses the current time, process id, and a counter as
a seed for the random number generator. The caller
must supply space for the output key, pointed to by
argument _k_e_y, then after calling _d_e_s__r_a_n_d_o_m__k_e_y should call
the _d_e_s__s_e_t__k_e_y routine when needed. No meaningful value is
returned. Void is not used for compatibility with other
compilers.
_d_e_s__s_e_t__k_e_y calculates a key schedule from all eight bytes
of the input key, pointed to by the _k_e_y argument, and out-
puts the schedule into the _d_e_s__k_e_y__s_c_h_e_d_u_l_e indicated by the
_s_c_h_e_d_u_l_e argument. Make sure to pass a valid eight byte key;
no padding is done. The key schedule may then be used in
subsequent encryption/decryption/checksum operations. Many
key schedules may be cached for later use. The user is
responsible to clear keys and schedules as soon as no longer
needed, to prevent their disclosure. The routine also
checks the key parity, and returns a zero if the key parity
is correct (odd), a -1 indicating a key parity error, or a
-2 indicating use of an illegal weak key. If an error is
returned, the key schedule was not created.
_d_e_s__e_c_b__e_n_c_r_y_p_t is the basic DES encryption routine that
encrypts or decrypts a single 8-byte block in eelleeccttrroonniicc
ccooddee bbooookk mode. It always transforms the input data,
pointed to by _i_n_p_u_t, into the output data, pointed to by the
_o_u_t_p_u_t argument.
If the _e_n_c_r_y_p_t argument is non-zero, the _i_n_p_u_t (cleartext)
is encrypted into the _o_u_t_p_u_t (ciphertext) using the
key_schedule specified by the _s_c_h_e_d_u_l_e argument, previously
set via _d_e_s__s_e_t__k_e_y
If encrypt is zero, the _i_n_p_u_t (now ciphertext) is decrypted
into the _o_u_t_p_u_t (now cleartext).
Input and output may overlap.
No meaningful value is returned. Void is not used for com-
patibility with other compilers.
Printed 7/27/90 Kerberos 3
DES_CRYPT(3) 4.0 DES_CRYPT(3)
_d_e_s__c_b_c__e_n_c_r_y_p_t encrypts/decrypts using the cciipphheerr--bblloocckk--
cchhaaiinniinngg mmooddee ooff DDEESS.. If the _e_n_c_r_y_p_t argument is non-zero,
the routine cipher-block-chain encrypts the cleartext data
pointed to by the _i_n_p_u_t argument into the ciphertext pointed
to by the _o_u_t_p_u_t argument, using the key schedule provided
by the _s_c_h_e_d_u_l_e argument, and initialization vector provided
by the _i_v_e_c argument. If the _l_e_n_g_t_h argument is not an
integral multiple of eight bytes, the last block is copied
to a temp and zero filled (highest addresses). The output
is ALWAYS an integral multiple of eight bytes.
If _e_n_c_r_y_p_t is zero, the routine cipher-block chain decrypts
the (now) ciphertext data pointed to by the _i_n_p_u_t argument
into (now) cleartext pointed to by the _o_u_t_p_u_t argument using
the key schedule provided by the _s_c_h_e_d_u_l_e argument, and ini-
tialization vector provided by the _i_v_e_c argument. Decryption
ALWAYS operates on integral multiples of 8 bytes, so it will
round the _l_e_n_g_t_h provided up to the appropriate multiple.
Consequently, it will always produce the rounded-up number
of bytes of output cleartext. The application must determine
if the output cleartext was zero-padded due to original
cleartext lengths that were not integral multiples of 8.
No errors or meaningful values are returned. Void is not
used for compatibility with other compilers.
A characteristic of cbc mode is that changing a single bit
of the cleartext, then encrypting using cbc mode, affects
ALL the subsequent ciphertext. This makes cryptanalysis
much more difficult. However, modifying a single bit of the
ciphertext, then decrypting, only affects the resulting
cleartext from the modified block and the succeeding block.
Therefore, _d_e_s__p_c_b_c__e_n_c_r_y_p_t is STRONGLY recommended for
applications where indefinite propagation of errors is
required in order to detect modifications.
_d_e_s__p_c_b_c__e_n_c_r_y_p_t encrypts/decrypts using a modified block
chaining mode. Its calling sequence is identical to
_d_e_s__c_b_c__e_n_c_r_y_p_t. It differs in its error propagation charac-
teristics.
_d_e_s__p_c_b_c__e_n_c_r_y_p_t is highly recommended for most encryption
purposes, in that modification of a single bit of the
ciphertext will affect ALL the subsequent (decrypted) clear-
text. Similarly, modifying a single bit of the cleartext
will affect ALL the subsequent (encrypted) ciphertext.
"PCBC" mode, on encryption, "xors" both the cleartext of
block N and the ciphertext resulting from block N with the
cleartext for block N+1 prior to encrypting block N+1.
_d_e_s__c_b_c__c_k_s_u_m produces an 8 byte cryptographic checksum by
cipher-block-chain encrypting the cleartext data pointed to
Printed 7/27/90 Kerberos 4
DES_CRYPT(3) 4.0 DES_CRYPT(3)
by the _i_n_p_u_t argument. All of the ciphertext output is dis-
carded, except the last 8-byte ciphertext block, which is
written into the area pointed to by the _o_u_t_p_u_t argument. It
uses the key schedule, provided by the _s_c_h_e_d_u_l_e argument and
initialization vector provided by the _i_v_e_c argument. If the
_l_e_n_g_t_h argument is not an integral multiple of eight bytes,
the last cleartext block is copied to a temp and zero filled
(highest addresses). The output is ALWAYS eight bytes.
The routine also returns an unsigned long, which is the last
(highest address) half of the 8 byte checksum computed.
_q_u_a_d__c_k_s_u_m produces a checksum by chaining quadratic opera-
tions on the cleartext data pointed to by the _i_n_p_u_t argu-
ment. The _l_e_n_g_t_h argument specifies the length of the input
-- only exactly that many bytes are included for the check-
sum, without any padding.
The algorithm may be iterated over the same input data, if
the _o_u_t__c_o_u_n_t argument is 2, 3 or 4, and the optional _o_u_t_p_u_t
argument is a non-null pointer . The default is one itera-
tion, and it will not run more than 4 times. Multiple itera-
tions run slower, but provide a longer checksum if desired.
The _s_e_e_d argument provides an 8-byte seed for the first
iteration. If multiple iterations are requested, the results
of one iteration are automatically used as the seed for the
next iteration.
It returns both an unsigned long checksum value, and if the
_o_u_t_p_u_t argument is not a null pointer, up to 16 bytes of the
computed checksum are written into the output.
FFIILLEESS
/usr/include/kerberosIV/des.h
/usr/lib/libdes.a
SSEEEE AALLSSOO
DDIIAAGGNNOOSSTTIICCSS
BBUUGGSS
This software has not yet been compiled or tested on
machines other than the VAX and the IBM PC.
AAUUTTHHOORRSS
Steve Miller, MIT Project Athena/Digital Equipment Corpora-
tion
RREESSTTRRIICCTTIIOONNSS
COPYRIGHT 1985,1986 Massachusetts Institute of Technology
This software may not be exported outside of the US without
a special license from the US Dept of Commerce. It may be
replaced by any secret key block cipher with block length
Printed 7/27/90 Kerberos 5
DES_CRYPT(3) 4.0 DES_CRYPT(3)
and key length of 8 bytes, as long as the interface is the
same as described here.
Printed 7/27/90 Kerberos 6