.\" $OpenBSD: DES_set_key.3,v 1.17 2024/05/24 19:18:07 tb Exp $ .\" full merge up to: .\" OpenSSL man3/DES_random_key 521738e9 Oct 5 14:58:30 2018 -0400 .\" .\" -------------------------------------------------------------------------- .\" Major patches to this file were contributed by .\" Ulf Moeller , Ben Laurie , .\" and Richard Levitte . .\" -------------------------------------------------------------------------- .\" Copyright (c) 2000, 2001, 2017 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. 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IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" The licence and distribution terms for any publically available version or .\" derivative of this code cannot be changed. i.e. this code cannot simply be .\" copied and put under another distribution licence .\" [including the GNU Public Licence.] .\" .Dd $Mdocdate: May 24 2024 $ .Dt DES_SET_KEY 3 .Os .Sh NAME .Nm DES_random_key , .Nm DES_set_key , .Nm DES_key_sched , .Nm DES_set_key_checked , .Nm DES_set_key_unchecked , .Nm DES_set_odd_parity , .Nm DES_is_weak_key , .Nm DES_ecb_encrypt , .Nm DES_ecb2_encrypt , .Nm DES_ecb3_encrypt , .Nm DES_ncbc_encrypt , .Nm DES_cfb_encrypt , .Nm DES_ofb_encrypt , .Nm DES_pcbc_encrypt , .Nm DES_cfb64_encrypt , .Nm DES_ofb64_encrypt , .Nm DES_xcbc_encrypt , .Nm DES_ede2_cbc_encrypt , .Nm DES_ede2_cfb64_encrypt , .Nm DES_ede2_ofb64_encrypt , .Nm DES_ede3_cbc_encrypt , .Nm DES_ede3_cbcm_encrypt , .Nm DES_ede3_cfb64_encrypt , .Nm DES_ede3_ofb64_encrypt , .Nm DES_cbc_cksum , .Nm DES_quad_cksum , .Nm DES_string_to_key , .Nm DES_string_to_2keys , .Nm DES_fcrypt , .Nm DES_crypt .Nd DES encryption .Sh SYNOPSIS .In openssl/des.h .Ft void .Fo DES_random_key .Fa "DES_cblock *ret" .Fc .Ft int .Fo DES_set_key .Fa "const_DES_cblock *key" .Fa "DES_key_schedule *schedule" .Fc .Ft int .Fo DES_key_sched .Fa "const_DES_cblock *key" .Fa "DES_key_schedule *schedule" .Fc .Ft int .Fo DES_set_key_checked .Fa "const_DES_cblock *key" .Fa "DES_key_schedule *schedule" .Fc .Ft void .Fo DES_set_key_unchecked .Fa "const_DES_cblock *key" .Fa "DES_key_schedule *schedule" .Fc .Ft void .Fo DES_set_odd_parity .Fa "DES_cblock *key" .Fc .Ft int .Fo DES_is_weak_key .Fa "const_DES_cblock *key" .Fc .Ft void .Fo DES_ecb_encrypt .Fa "const_DES_cblock *input" .Fa "DES_cblock *output" .Fa "DES_key_schedule *ks" .Fa "int enc" .Fc .Ft void .Fo DES_ecb2_encrypt .Fa "const_DES_cblock *input" .Fa "DES_cblock *output" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "int enc" .Fc .Ft void .Fo DES_ecb3_encrypt .Fa "const_DES_cblock *input" .Fa "DES_cblock *output" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_key_schedule *ks3" .Fa "int enc" .Fc .Ft void .Fo DES_ncbc_encrypt .Fa "const unsigned char *input" .Fa "unsigned char *output" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "int enc" .Fc .Ft void .Fo DES_cfb_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "int numbits" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "int enc" .Fc .Ft void .Fo DES_ofb_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "int numbits" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fc .Ft void .Fo DES_pcbc_encrypt .Fa "const unsigned char *input" .Fa "unsigned char *output" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "int enc" .Fc .Ft void .Fo DES_cfb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "int *num" .Fa "int enc" .Fc .Ft void .Fo DES_ofb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "int *num" .Fc .Ft void .Fo DES_xcbc_encrypt .Fa "const unsigned char *input" .Fa "unsigned char *output" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "DES_cblock *ivec" .Fa "const_DES_cblock *inw" .Fa "const_DES_cblock *outw" .Fa "int enc" .Fc .Ft void .Fo DES_ede2_cbc_encrypt .Fa "const unsigned char *input" .Fa "unsigned char *output" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_cblock *ivec" .Fa "int enc" .Fc .Ft void .Fo DES_ede2_cfb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_cblock *ivec" .Fa "int *num" .Fa "int enc" .Fc .Ft void .Fo DES_ede2_ofb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_cblock *ivec" .Fa "int *num" .Fc .Ft void .Fo DES_ede3_cbc_encrypt .Fa "const unsigned char *input" .Fa "unsigned char *output" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_key_schedule *ks3" .Fa "DES_cblock *ivec" .Fa "int enc" .Fc .Ft void .Fo DES_ede3_cbcm_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_key_schedule *ks3" .Fa "DES_cblock *ivec1" .Fa "DES_cblock *ivec2" .Fa "int enc" .Fc .Ft void .Fo DES_ede3_cfb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_key_schedule *ks3" .Fa "DES_cblock *ivec" .Fa "int *num" .Fa "int enc" .Fc .Ft void .Fo DES_ede3_ofb64_encrypt .Fa "const unsigned char *in" .Fa "unsigned char *out" .Fa "long length" .Fa "DES_key_schedule *ks1" .Fa "DES_key_schedule *ks2" .Fa "DES_key_schedule *ks3" .Fa "DES_cblock *ivec" .Fa "int *num" .Fc .Ft DES_LONG .Fo DES_cbc_cksum .Fa "const unsigned char *input" .Fa "DES_cblock *output" .Fa "long length" .Fa "DES_key_schedule *schedule" .Fa "const_DES_cblock *ivec" .Fc .Ft DES_LONG .Fo DES_quad_cksum .Fa "const unsigned char *input" .Fa "DES_cblock output[]" .Fa "long length" .Fa "int out_count" .Fa "DES_cblock *seed" .Fc .Ft void .Fo DES_string_to_key .Fa "const char *str" .Fa "DES_cblock *key" .Fc .Ft void .Fo DES_string_to_2keys .Fa "const char *str" .Fa "DES_cblock *key1" .Fa "DES_cblock *key2" .Fc .Ft char * .Fo DES_fcrypt .Fa "const char *buf" .Fa "const char *salt" .Fa "char *ret" .Fc .Ft char * .Fo DES_crypt .Fa "const char *buf" .Fa "const char *salt" .Fc .Sh DESCRIPTION This library contains a fast implementation of the DES encryption algorithm. .Pp There are two phases to the use of DES encryption. The first is the generation of a .Vt DES_key_schedule from a key, and the second is the actual encryption. A DES key is of type .Vt DES_cblock . This type consists of 8 bytes with odd parity. The least significant bit in each byte is the parity bit. The key schedule is an expanded form of the key; it is used to speed the encryption process. .Pp .Fn DES_random_key generates a random key in odd parity. .Pp Before a DES key can be used, it must be converted into the architecture dependent .Vt DES_key_schedule via the .Fn DES_set_key_checked or .Fn DES_set_key_unchecked function. .Pp .Fn DES_set_key_checked will check that the key passed is of odd parity and is not a weak or semi-weak key. If the parity is wrong, then -1 is returned. If the key is a weak key, then -2 is returned. If an error is returned, the key schedule is not generated. .Pp .Fn DES_set_key works like .Fn DES_set_key_checked if the .Em DES_check_key flag is non-zero, otherwise like .Fn DES_set_key_unchecked . These functions are available for compatibility; it is recommended to use a function that does not depend on a global variable. .Pp .Fn DES_set_odd_parity sets the parity of the passed .Fa key to odd. .Pp The following routines mostly operate on an input and output stream of .Vt DES_cblock Ns s . .Pp .Fn DES_ecb_encrypt is the basic DES encryption routine that encrypts or decrypts a single 8-byte .Vt DES_cblock in electronic code book (ECB) mode. It always transforms the input data, pointed to by .Fa input , into the output data, pointed to by the .Fa output argument. If the .Fa enc argument is non-zero .Pq Dv DES_ENCRYPT , the .Fa input (cleartext) is encrypted into the .Fa output (ciphertext) using the key_schedule specified by the .Fa schedule argument, previously set via .Fn DES_set_key . If .Fa enc is zero .Pq Dv DES_DECRYPT , the .Fa input (now ciphertext) is decrypted into the .Fa output (now cleartext). Input and output may overlap. .Fn DES_ecb_encrypt does not return a value. .Pp .Fn DES_ecb3_encrypt encrypts/decrypts the .Fa input block by using three-key Triple-DES encryption in ECB mode. This involves encrypting the input with .Fa ks1 , decrypting with the key schedule .Fa ks2 , and then encrypting with .Fa ks3 . This routine greatly reduces the chances of brute force breaking of DES and has the advantage of if .Fa ks1 , .Fa ks2 , and .Fa ks3 are the same, it is equivalent to just encryption using ECB mode and .Fa ks1 as the key. .Pp The macro .Fn DES_ecb2_encrypt is provided to perform two-key Triple-DES encryption by using .Fa ks1 for the final encryption. .Pp .Fn DES_ncbc_encrypt encrypts/decrypts using the cipher-block-chaining (CBC) mode of DES. If the .Fa enc argument is non-zero, the routine cipher-block-chain encrypts the cleartext data pointed to by the .Fa input argument into the ciphertext pointed to by the .Fa output argument, using the key schedule provided by the .Fa schedule argument, and initialization vector provided by the .Fa ivec argument. If the .Fa length argument is not an integral multiple of eight bytes, the last block is copied to a temporary area and zero filled. The output is always an integral multiple of eight bytes. .Pp .Fn DES_xcbc_encrypt is RSA's DESX mode of DES. It uses .Fa inw and .Fa outw to "whiten" the encryption. .Fa inw and .Fa outw are secret (unlike the iv) and are as such, part of the key. So the key is sort of 24 bytes. This is much better than CBC DES. .Pp .Fn DES_ede3_cbc_encrypt implements outer triple CBC DES encryption with three keys. This means that each DES operation inside the CBC mode is .Qq Li C=E(ks3,D(ks2,E(ks1,M))) . This mode is used by SSL. .Pp The .Fn DES_ede2_cbc_encrypt macro implements two-key Triple-DES by reusing .Fa ks1 for the final encryption. .Qq Li C=E(ks1,D(ks2,E(ks1,M))) . This form of Triple-DES is used by the RSAREF library. .Pp .Fn DES_pcbc_encrypt encrypts/decrypts using the propagating cipher block chaining mode used by Kerberos v4. Its parameters are the same as .Fn DES_ncbc_encrypt . .Pp .Fn DES_cfb_encrypt encrypts/decrypts using cipher feedback mode. This method takes an array of characters as input and outputs an array of characters. It does not require any padding to 8 character groups. Note: the .Fa ivec variable is changed and the new changed value needs to be passed to the next call to this function. Since this function runs a complete DES ECB encryption per .Fa numbits , this function is only suggested for use when sending a small number of characters. .Pp .Fn DES_cfb64_encrypt implements CFB mode of DES with 64-bit feedback. Why is this useful you ask? Because this routine will allow you to encrypt an arbitrary number of bytes, without 8 byte padding. Each call to this routine will encrypt the input bytes to output and then update ivec and num. num contains "how far" we are though ivec. If this does not make much sense, read more about CFB mode of DES. .Pp The .Fn DES_ede3_cfb64_encrypt function and the .Fn DES_ede2_cfb64_encrypt macro are the same as .Fn DES_cfb64_encrypt except that Triple-DES is used. .Pp .Fn DES_ofb_encrypt encrypts using output feedback mode. This method takes an array of characters as input and outputs an array of characters. It does not require any padding to 8 character groups. Note: the .Fa ivec variable is changed and the new changed value needs to be passed to the next call to this function. Since this function runs a complete DES ECB encryption per .Fa numbits , this function is only suggested for use when sending a small number of characters. .Pp .Fn DES_ofb64_encrypt is the same as .Fn DES_cfb64_encrypt using Output Feed Back mode. .Pp The .Fn DES_ede3_ofb64_encrypt function and the .Fn DES_ede2_ofb64_encrypt macro are the same as .Fn DES_ofb64_encrypt , using Triple-DES. .Pp The following functions are included in the DES library for compatibility with the MIT Kerberos library. .Pp .Fn DES_cbc_cksum produces an 8-byte checksum based on the input stream (via CBC encryption). The last 4 bytes of the checksum are returned and the complete 8 bytes are placed in .Fa output . This function is used by Kerberos v4. Other applications should use .Xr EVP_DigestInit 3 etc. instead. .Pp .Fn DES_quad_cksum is a Kerberos v4 function. It returns a 4-byte checksum from the input bytes. The algorithm can be iterated over the input, depending on .Fa out_count , 1, 2, 3 or 4 times. If .Fa output is .Pf non- Dv NULL , the 8 bytes generated by each pass are written into .Fa output . .Pp The following are DES-based transformations: .Pp .Fn DES_fcrypt is a fast version of the Unix .Xr crypt 3 function. The .Fa salt must be two ASCII characters. This version is different from the normal crypt in that the third parameter is the buffer that the return value is written into. It needs to be at least 14 bytes long. The fourteenth byte is set to NUL. This version takes only a small amount of space relative to other fast crypt implementations. It is thread safe, unlike the normal crypt. .Pp .Fn DES_crypt is a faster replacement for the normal system .Xr crypt 3 . This function calls .Fn DES_fcrypt with a static array passed as the third parameter. This emulates the normal non-thread safe semantics of .Xr crypt 3 . .Sh RETURN VALUES .Fn DES_set_key , .Fn DES_key_sched , and .Fn DES_set_key_checked return 0 on success or a negative value on error. .Pp .Fn DES_is_weak_key returns 1 if the passed key is a weak key or 0 if it is ok. .Pp .Fn DES_cbc_cksum and .Fn DES_quad_cksum return a 4-byte integer representing the last 4 bytes of the checksum of the input. .Pp .Fn DES_fcrypt returns a pointer to the caller-provided buffer .Fa ret , and .Fn DES_crypt returns a pointer to a static buffer. Both are allowed to return .Dv NULL to indicate failure, but currently, they cannot fail. .Sh SEE ALSO .Xr crypt 3 , .Xr EVP_des_cbc 3 , .Xr EVP_EncryptInit 3 .Sh STANDARDS ANSI X3.106 .Pp The DES library was initially written to be source code compatible with the MIT Kerberos library. .Sh HISTORY .Fn DES_random_key , .Fn DES_set_key , .Fn DES_key_sched , .Fn DES_set_odd_parity , .Fn DES_is_weak_key , .Fn DES_ecb_encrypt , .Fn DES_cfb_encrypt , .Fn DES_ofb_encrypt , .Fn DES_pcbc_encrypt , .Fn DES_cfb64_encrypt , .Fn DES_ofb64_encrypt , .Fn DES_ede3_cbc_encrypt , .Fn DES_cbc_cksum , .Fn DES_quad_cksum , .Fn DES_string_to_key , .Fn DES_string_to_2keys , and .Fn DES_crypt appeared in SSLeay 0.4 or earlier. .Fn DES_ncbc_encrypt first appeared in SSLeay 0.4.2. .Fn DES_ede2_cbc_encrypt first appeared in SSLeay 0.4.4. .Fn DES_ecb2_encrypt , .Fn DES_ecb3_encrypt , .Fn DES_ede2_cfb64_encrypt , .Fn DES_ede2_ofb64_encrypt , .Fn DES_ede3_cfb64_encrypt , and .Fn DES_ede3_ofb64_encrypt first appeared in SSLeay 0.5.1. .Fn DES_xcbc_encrypt first appeared in SSLeay 0.6.2. .Fn DES_fcrypt first appeared in SSLeay 0.6.5. These functions have been available since .Ox 2.4 . .Pp .Fn DES_set_key_checked and .Fn DES_set_key_unchecked first appeared in OpenSSL 0.9.5 and have been available since .Ox 2.7 . .Pp In OpenSSL 0.9.7 and .Ox 3.2 , all .Sy des_ functions were renamed to .Sy DES_ to avoid clashes with older versions of libdes. .Sh AUTHORS .An Eric Young Aq Mt eay@cryptsoft.com .Sh CAVEATS Single-key DES is insecure due to its short key size. ECB mode is not suitable for most applications. .Sh BUGS DES_cbc_encrypt does not modify .Fa ivec ; use .Fn DES_ncbc_encrypt instead. .Pp .Fn DES_cfb_encrypt and .Fn DES_ofb_encrypt operates on input of 8 bits. What this means is that if you set numbits to 12, and length to 2, the first 12 bits will come from the 1st input byte and the low half of the second input byte. The second 12 bits will have the low 8 bits taken from the 3rd input byte and the top 4 bits taken from the 4th input byte. The same holds for output. This function has been implemented this way because most people will be using a multiple of 8 and because once you get into pulling input bytes apart things get ugly! .Pp .Fn DES_string_to_key is available for backward compatibility with the MIT library. New applications should use a cryptographic hash function. The same applies for .Fn DES_string_to_2key .