4.4BSD/usr/share/man/cat3/des.0
DES_CRYPT(3) BSD Programmer's Manual 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;;
MIT Project Athena Kerberos Version 4.0 1
DES_CRYPT(3) BSD Programmer's Manual DES_CRYPT(3)
ddeess__kkeeyy__sscchheedduullee sscchheedduullee;;
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 oper-
ations. 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 encryp-
tion, 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
routines. 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 check-
sum, 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 funda-
mental 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 chang-
ing 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 converts 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
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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 par-
ity, 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 compatibility 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 oper-
ations. 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, previ-
ously set via _d_e_s___s_e_t___k_e_y
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DES_CRYPT(3) BSD Programmer's Manual DES_CRYPT(3)
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
compatibility with other compilers.
_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 cleart-
ext data pointed to by the _i_n_p_u_t argument into the cipher-
text 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 initial-
ization 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 initialization 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 result-
ing 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 recom-
mended 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
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DES_CRYPT(3) BSD Programmer's Manual DES_CRYPT(3)
characteristics.
_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)
cleartext. Similarly, modifying a single bit of the clear-
text will affect ALL the subsequent (encrypted) cipher-
text. "PCBC" mode, on encryption, "xors" both the cleart-
ext 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 by the _i_n_p_u_t argument. All of the ciphertext output is
discarded, except the last 8-byte ciphertext block, which
is written into the area pointed to by the _o_u_t_p_u_t argu-
ment. 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 mul-
tiple 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 com-
puted.
_q_u_a_d___c_k_s_u_m produces a checksum by chaining quadratic oper-
ations 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
checksum, 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
iteration, and it will not run more than 4 times. Multiple
iterations 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.
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DES_CRYPT(3) BSD Programmer's Manual DES_CRYPT(3)
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 Corpo-
ration
RREESSTTRRIICCTTIIOONNSS
COPYRIGHT 1985,1986 Massachusetts Institute of Technology
This software may not be exported outside of the US with-
out a special license from the US Dept of Commerce. It may
be replaced by any secret key block cipher with block
length and key length of 8 bytes, as long as the interface
is the same as described here.
MIT Project Athena Kerberos Version 4.0 6