1=pod 2 3=head1 NAME 4 5DES_random_key, DES_set_key, DES_key_sched, DES_set_key_checked, 6DES_set_key_unchecked, DES_set_odd_parity, DES_is_weak_key, 7DES_ecb_encrypt, DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt, 8DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt, DES_cfb64_encrypt, 9DES_ofb64_encrypt, DES_xcbc_encrypt, DES_ede2_cbc_encrypt, 10DES_ede2_cfb64_encrypt, DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt, 11DES_ede3_cbcm_encrypt, DES_ede3_cfb64_encrypt, DES_ede3_ofb64_encrypt, 12DES_cbc_cksum, DES_quad_cksum, DES_string_to_key, DES_string_to_2keys, 13DES_fcrypt, DES_crypt, DES_enc_read, DES_enc_write - DES encryption 14 15=head1 SYNOPSIS 16 17 #include <openssl/des.h> 18 19 void DES_random_key(DES_cblock *ret); 20 21 int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule); 22 int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule); 23 int DES_set_key_checked(const_DES_cblock *key, 24 DES_key_schedule *schedule); 25 void DES_set_key_unchecked(const_DES_cblock *key, 26 DES_key_schedule *schedule); 27 28 void DES_set_odd_parity(DES_cblock *key); 29 int DES_is_weak_key(const_DES_cblock *key); 30 31 void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output, 32 DES_key_schedule *ks, int enc); 33 void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output, 34 DES_key_schedule *ks1, DES_key_schedule *ks2, int enc); 35 void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output, 36 DES_key_schedule *ks1, DES_key_schedule *ks2, 37 DES_key_schedule *ks3, int enc); 38 39 void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output, 40 long length, DES_key_schedule *schedule, DES_cblock *ivec, 41 int enc); 42 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, 43 int numbits, long length, DES_key_schedule *schedule, 44 DES_cblock *ivec, int enc); 45 void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, 46 int numbits, long length, DES_key_schedule *schedule, 47 DES_cblock *ivec); 48 void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output, 49 long length, DES_key_schedule *schedule, DES_cblock *ivec, 50 int enc); 51 void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out, 52 long length, DES_key_schedule *schedule, DES_cblock *ivec, 53 int *num, int enc); 54 void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out, 55 long length, DES_key_schedule *schedule, DES_cblock *ivec, 56 int *num); 57 58 void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output, 59 long length, DES_key_schedule *schedule, DES_cblock *ivec, 60 const_DES_cblock *inw, const_DES_cblock *outw, int enc); 61 62 void DES_ede2_cbc_encrypt(const unsigned char *input, 63 unsigned char *output, long length, DES_key_schedule *ks1, 64 DES_key_schedule *ks2, DES_cblock *ivec, int enc); 65 void DES_ede2_cfb64_encrypt(const unsigned char *in, 66 unsigned char *out, long length, DES_key_schedule *ks1, 67 DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc); 68 void DES_ede2_ofb64_encrypt(const unsigned char *in, 69 unsigned char *out, long length, DES_key_schedule *ks1, 70 DES_key_schedule *ks2, DES_cblock *ivec, int *num); 71 72 void DES_ede3_cbc_encrypt(const unsigned char *input, 73 unsigned char *output, long length, DES_key_schedule *ks1, 74 DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec, 75 int enc); 76 void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out, 77 long length, DES_key_schedule *ks1, DES_key_schedule *ks2, 78 DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2, 79 int enc); 80 void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out, 81 long length, DES_key_schedule *ks1, DES_key_schedule *ks2, 82 DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc); 83 void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out, 84 long length, DES_key_schedule *ks1, 85 DES_key_schedule *ks2, DES_key_schedule *ks3, 86 DES_cblock *ivec, int *num); 87 88 DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output, 89 long length, DES_key_schedule *schedule, 90 const_DES_cblock *ivec); 91 DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[], 92 long length, int out_count, DES_cblock *seed); 93 void DES_string_to_key(const char *str, DES_cblock *key); 94 void DES_string_to_2keys(const char *str, DES_cblock *key1, 95 DES_cblock *key2); 96 97 char *DES_fcrypt(const char *buf, const char *salt, char *ret); 98 char *DES_crypt(const char *buf, const char *salt); 99 100 int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched, 101 DES_cblock *iv); 102 int DES_enc_write(int fd, const void *buf, int len, 103 DES_key_schedule *sched, DES_cblock *iv); 104 105=head1 DESCRIPTION 106 107This library contains a fast implementation of the DES encryption 108algorithm. 109 110There are two phases to the use of DES encryption. The first is the 111generation of a I<DES_key_schedule> from a key, the second is the 112actual encryption. A DES key is of type I<DES_cblock>. This type is 113consists of 8 bytes with odd parity. The least significant bit in 114each byte is the parity bit. The key schedule is an expanded form of 115the key; it is used to speed the encryption process. 116 117DES_random_key() generates a random key. The PRNG must be seeded 118prior to using this function (see L<rand(3)|rand(3)>). If the PRNG 119could not generate a secure key, 0 is returned. 120 121Before a DES key can be used, it must be converted into the 122architecture dependent I<DES_key_schedule> via the 123DES_set_key_checked() or DES_set_key_unchecked() function. 124 125DES_set_key_checked() will check that the key passed is of odd parity 126and is not a week or semi-weak key. If the parity is wrong, then -1 127is returned. If the key is a weak key, then -2 is returned. If an 128error is returned, the key schedule is not generated. 129 130DES_set_key() works like 131DES_set_key_checked() if the I<DES_check_key> flag is non-zero, 132otherwise like DES_set_key_unchecked(). These functions are available 133for compatibility; it is recommended to use a function that does not 134depend on a global variable. 135 136DES_set_odd_parity() sets the parity of the passed I<key> to odd. 137 138DES_is_weak_key() returns 1 is the passed key is a weak key, 0 if it 139is ok. The probability that a randomly generated key is weak is 1401/2^52, so it is not really worth checking for them. 141 142The following routines mostly operate on an input and output stream of 143I<DES_cblock>s. 144 145DES_ecb_encrypt() is the basic DES encryption routine that encrypts or 146decrypts a single 8-byte I<DES_cblock> in I<electronic code book> 147(ECB) mode. It always transforms the input data, pointed to by 148I<input>, into the output data, pointed to by the I<output> argument. 149If the I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input> 150(cleartext) is encrypted in to the I<output> (ciphertext) using the 151key_schedule specified by the I<schedule> argument, previously set via 152I<DES_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now 153ciphertext) is decrypted into the I<output> (now cleartext). Input 154and output may overlap. DES_ecb_encrypt() does not return a value. 155 156DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using 157three-key Triple-DES encryption in ECB mode. This involves encrypting 158the input with I<ks1>, decrypting with the key schedule I<ks2>, and 159then encrypting with I<ks3>. This routine greatly reduces the chances 160of brute force breaking of DES and has the advantage of if I<ks1>, 161I<ks2> and I<ks3> are the same, it is equivalent to just encryption 162using ECB mode and I<ks1> as the key. 163 164The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES 165encryption by using I<ks1> for the final encryption. 166 167DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining> 168(CBC) mode of DES. If the I<encrypt> argument is non-zero, the 169routine cipher-block-chain encrypts the cleartext data pointed to by 170the I<input> argument into the ciphertext pointed to by the I<output> 171argument, using the key schedule provided by the I<schedule> argument, 172and initialization vector provided by the I<ivec> argument. If the 173I<length> argument is not an integral multiple of eight bytes, the 174last block is copied to a temporary area and zero filled. The output 175is always an integral multiple of eight bytes. 176 177DES_xcbc_encrypt() is RSA's DESX mode of DES. It uses I<inw> and 178I<outw> to 'whiten' the encryption. I<inw> and I<outw> are secret 179(unlike the iv) and are as such, part of the key. So the key is sort 180of 24 bytes. This is much better than CBC DES. 181 182DES_ede3_cbc_encrypt() implements outer triple CBC DES encryption with 183three keys. This means that each DES operation inside the CBC mode is 184really an C<C=E(ks3,D(ks2,E(ks1,M)))>. This mode is used by SSL. 185 186The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by 187reusing I<ks1> for the final encryption. C<C=E(ks1,D(ks2,E(ks1,M)))>. 188This form of Triple-DES is used by the RSAREF library. 189 190DES_pcbc_encrypt() encrypt/decrypts using the propagating cipher block 191chaining mode used by Kerberos v4. Its parameters are the same as 192DES_ncbc_encrypt(). 193 194DES_cfb_encrypt() encrypt/decrypts using cipher feedback mode. This 195method takes an array of characters as input and outputs and array of 196characters. It does not require any padding to 8 character groups. 197Note: the I<ivec> variable is changed and the new changed value needs to 198be passed to the next call to this function. Since this function runs 199a complete DES ECB encryption per I<numbits>, this function is only 200suggested for use when sending small numbers of characters. 201 202DES_cfb64_encrypt() 203implements CFB mode of DES with 64bit feedback. Why is this 204useful you ask? Because this routine will allow you to encrypt an 205arbitrary number of bytes, no 8 byte padding. Each call to this 206routine will encrypt the input bytes to output and then update ivec 207and num. num contains 'how far' we are though ivec. If this does 208not make much sense, read more about cfb mode of DES :-). 209 210DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as 211DES_cfb64_encrypt() except that Triple-DES is used. 212 213DES_ofb_encrypt() encrypts using output feedback mode. This method 214takes an array of characters as input and outputs and array of 215characters. It does not require any padding to 8 character groups. 216Note: the I<ivec> variable is changed and the new changed value needs to 217be passed to the next call to this function. Since this function runs 218a complete DES ECB encryption per numbits, this function is only 219suggested for use when sending small numbers of characters. 220 221DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output 222Feed Back mode. 223 224DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as 225DES_ofb64_encrypt(), using Triple-DES. 226 227The following functions are included in the DES library for 228compatibility with the MIT Kerberos library. 229 230DES_cbc_cksum() produces an 8 byte checksum based on the input stream 231(via CBC encryption). The last 4 bytes of the checksum are returned 232and the complete 8 bytes are placed in I<output>. This function is 233used by Kerberos v4. Other applications should use 234L<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead. 235 236DES_quad_cksum() is a Kerberos v4 function. It returns a 4 byte 237checksum from the input bytes. The algorithm can be iterated over the 238input, depending on I<out_count>, 1, 2, 3 or 4 times. If I<output> is 239non-NULL, the 8 bytes generated by each pass are written into 240I<output>. 241 242The following are DES-based transformations: 243 244DES_fcrypt() is a fast version of the Unix crypt(3) function. This 245version takes only a small amount of space relative to other fast 246crypt() implementations. This is different to the normal crypt in 247that the third parameter is the buffer that the return value is 248written into. It needs to be at least 14 bytes long. This function 249is thread safe, unlike the normal crypt. 250 251DES_crypt() is a faster replacement for the normal system crypt(). 252This function calls DES_fcrypt() with a static array passed as the 253third parameter. This emulates the normal non-thread safe semantics 254of crypt(3). 255 256DES_enc_write() writes I<len> bytes to file descriptor I<fd> from 257buffer I<buf>. The data is encrypted via I<pcbc_encrypt> (default) 258using I<sched> for the key and I<iv> as a starting vector. The actual 259data send down I<fd> consists of 4 bytes (in network byte order) 260containing the length of the following encrypted data. The encrypted 261data then follows, padded with random data out to a multiple of 8 262bytes. 263 264DES_enc_read() is used to read I<len> bytes from file descriptor 265I<fd> into buffer I<buf>. The data being read from I<fd> is assumed to 266have come from DES_enc_write() and is decrypted using I<sched> for 267the key schedule and I<iv> for the initial vector. 268 269B<Warning:> The data format used by DES_enc_write() and DES_enc_read() 270has a cryptographic weakness: When asked to write more than MAXWRITE 271bytes, DES_enc_write() will split the data into several chunks that 272are all encrypted using the same IV. So don't use these functions 273unless you are sure you know what you do (in which case you might not 274want to use them anyway). They cannot handle non-blocking sockets. 275DES_enc_read() uses an internal state and thus cannot be used on 276multiple files. 277 278I<DES_rw_mode> is used to specify the encryption mode to use with 279DES_enc_read() and DES_end_write(). If set to I<DES_PCBC_MODE> (the 280default), DES_pcbc_encrypt is used. If set to I<DES_CBC_MODE> 281DES_cbc_encrypt is used. 282 283=head1 NOTES 284 285Single-key DES is insecure due to its short key size. ECB mode is 286not suitable for most applications; see L<des_modes(7)|des_modes(7)>. 287 288The L<evp(3)|evp(3)> library provides higher-level encryption functions. 289 290=head1 BUGS 291 292DES_3cbc_encrypt() is flawed and must not be used in applications. 293 294DES_cbc_encrypt() does not modify B<ivec>; use DES_ncbc_encrypt() 295instead. 296 297DES_cfb_encrypt() and DES_ofb_encrypt() operates on input of 8 bits. 298What this means is that if you set numbits to 12, and length to 2, the 299first 12 bits will come from the 1st input byte and the low half of 300the second input byte. The second 12 bits will have the low 8 bits 301taken from the 3rd input byte and the top 4 bits taken from the 4th 302input byte. The same holds for output. This function has been 303implemented this way because most people will be using a multiple of 8 304and because once you get into pulling bytes input bytes apart things 305get ugly! 306 307DES_string_to_key() is available for backward compatibility with the 308MIT library. New applications should use a cryptographic hash function. 309The same applies for DES_string_to_2key(). 310 311=head1 CONFORMING TO 312 313ANSI X3.106 314 315The B<des> library was written to be source code compatible with 316the MIT Kerberos library. 317 318=head1 SEE ALSO 319 320crypt(3), L<des_modes(7)|des_modes(7)>, L<evp(3)|evp(3)>, L<rand(3)|rand(3)> 321 322=head1 HISTORY 323 324In OpenSSL 0.9.7, all des_ functions were renamed to DES_ to avoid 325clashes with older versions of libdes. Compatibility des_ functions 326are provided for a short while, as well as crypt(). 327Declarations for these are in <openssl/des_old.h>. There is no DES_ 328variant for des_random_seed(). 329This will happen to other functions 330as well if they are deemed redundant (des_random_seed() just calls 331RAND_seed() and is present for backward compatibility only), buggy or 332already scheduled for removal. 333 334des_cbc_cksum(), des_cbc_encrypt(), des_ecb_encrypt(), 335des_is_weak_key(), des_key_sched(), des_pcbc_encrypt(), 336des_quad_cksum(), des_random_key() and des_string_to_key() 337are available in the MIT Kerberos library; 338des_check_key_parity(), des_fixup_key_parity() and des_is_weak_key() 339are available in newer versions of that library. 340 341des_set_key_checked() and des_set_key_unchecked() were added in 342OpenSSL 0.9.5. 343 344des_generate_random_block(), des_init_random_number_generator(), 345des_new_random_key(), des_set_random_generator_seed() and 346des_set_sequence_number() and des_rand_data() are used in newer 347versions of Kerberos but are not implemented here. 348 349des_random_key() generated cryptographically weak random data in 350SSLeay and in OpenSSL prior version 0.9.5, as well as in the original 351MIT library. 352 353=head1 AUTHOR 354 355Eric Young (eay@cryptsoft.com). Modified for the OpenSSL project 356(http://www.openssl.org). 357 358=cut 359