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Diffstat (limited to 'openssl/doc/crypto/des.pod')
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diff --git a/openssl/doc/crypto/des.pod b/openssl/doc/crypto/des.pod new file mode 100644 index 000000000..6f0cf1cc5 --- /dev/null +++ b/openssl/doc/crypto/des.pod @@ -0,0 +1,358 @@ +=pod + +=head1 NAME + +DES_random_key, DES_set_key, DES_key_sched, DES_set_key_checked, +DES_set_key_unchecked, DES_set_odd_parity, DES_is_weak_key, +DES_ecb_encrypt, DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt, +DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt, DES_cfb64_encrypt, +DES_ofb64_encrypt, DES_xcbc_encrypt, DES_ede2_cbc_encrypt, +DES_ede2_cfb64_encrypt, DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt, +DES_ede3_cbcm_encrypt, DES_ede3_cfb64_encrypt, DES_ede3_ofb64_encrypt, +DES_cbc_cksum, DES_quad_cksum, DES_string_to_key, DES_string_to_2keys, +DES_fcrypt, DES_crypt, DES_enc_read, DES_enc_write - DES encryption + +=head1 SYNOPSIS + + #include <openssl/des.h> + + void DES_random_key(DES_cblock *ret); + + int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule); + int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule); + int DES_set_key_checked(const_DES_cblock *key, + DES_key_schedule *schedule); + void DES_set_key_unchecked(const_DES_cblock *key, + DES_key_schedule *schedule); + + void DES_set_odd_parity(DES_cblock *key); + int DES_is_weak_key(const_DES_cblock *key); + + void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output, + DES_key_schedule *ks, int enc); + void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output, + DES_key_schedule *ks1, DES_key_schedule *ks2, int enc); + void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output, + DES_key_schedule *ks1, DES_key_schedule *ks2, + DES_key_schedule *ks3, int enc); + + void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output, + long length, DES_key_schedule *schedule, DES_cblock *ivec, + int enc); + void DES_cfb_encrypt(const unsigned char *in, unsigned char *out, + int numbits, long length, DES_key_schedule *schedule, + DES_cblock *ivec, int enc); + void DES_ofb_encrypt(const unsigned char *in, unsigned char *out, + int numbits, long length, DES_key_schedule *schedule, + DES_cblock *ivec); + void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output, + long length, DES_key_schedule *schedule, DES_cblock *ivec, + int enc); + void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out, + long length, DES_key_schedule *schedule, DES_cblock *ivec, + int *num, int enc); + void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out, + long length, DES_key_schedule *schedule, DES_cblock *ivec, + int *num); + + void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output, + long length, DES_key_schedule *schedule, DES_cblock *ivec, + const_DES_cblock *inw, const_DES_cblock *outw, int enc); + + void DES_ede2_cbc_encrypt(const unsigned char *input, + unsigned char *output, long length, DES_key_schedule *ks1, + DES_key_schedule *ks2, DES_cblock *ivec, int enc); + void DES_ede2_cfb64_encrypt(const unsigned char *in, + unsigned char *out, long length, DES_key_schedule *ks1, + DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc); + void DES_ede2_ofb64_encrypt(const unsigned char *in, + unsigned char *out, long length, DES_key_schedule *ks1, + DES_key_schedule *ks2, DES_cblock *ivec, int *num); + + void DES_ede3_cbc_encrypt(const unsigned char *input, + unsigned char *output, long length, DES_key_schedule *ks1, + DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec, + int enc); + void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out, + long length, DES_key_schedule *ks1, DES_key_schedule *ks2, + DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2, + int enc); + void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out, + long length, DES_key_schedule *ks1, DES_key_schedule *ks2, + DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc); + void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out, + long length, DES_key_schedule *ks1, + DES_key_schedule *ks2, DES_key_schedule *ks3, + DES_cblock *ivec, int *num); + + DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output, + long length, DES_key_schedule *schedule, + const_DES_cblock *ivec); + DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[], + long length, int out_count, DES_cblock *seed); + void DES_string_to_key(const char *str, DES_cblock *key); + void DES_string_to_2keys(const char *str, DES_cblock *key1, + DES_cblock *key2); + + char *DES_fcrypt(const char *buf, const char *salt, char *ret); + char *DES_crypt(const char *buf, const char *salt); + + int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched, + DES_cblock *iv); + int DES_enc_write(int fd, const void *buf, int len, + DES_key_schedule *sched, DES_cblock *iv); + +=head1 DESCRIPTION + +This library contains a fast implementation of the DES encryption +algorithm. + +There are two phases to the use of DES encryption. The first is the +generation of a I<DES_key_schedule> from a key, the second is the +actual encryption. A DES key is of type I<DES_cblock>. This type is +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. + +DES_random_key() generates a random key. The PRNG must be seeded +prior to using this function (see L<rand(3)|rand(3)>). If the PRNG +could not generate a secure key, 0 is returned. + +Before a DES key can be used, it must be converted into the +architecture dependent I<DES_key_schedule> via the +DES_set_key_checked() or DES_set_key_unchecked() function. + +DES_set_key_checked() will check that the key passed is of odd parity +and is not a week 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. + +DES_set_key() works like +DES_set_key_checked() if the I<DES_check_key> flag is non-zero, +otherwise like 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. + +DES_set_odd_parity() sets the parity of the passed I<key> to odd. + +DES_is_weak_key() returns 1 is the passed key is a weak key, 0 if it +is ok. The probability that a randomly generated key is weak is +1/2^52, so it is not really worth checking for them. + +The following routines mostly operate on an input and output stream of +I<DES_cblock>s. + +DES_ecb_encrypt() is the basic DES encryption routine that encrypts or +decrypts a single 8-byte I<DES_cblock> in I<electronic code book> +(ECB) mode. It always transforms the input data, pointed to by +I<input>, into the output data, pointed to by the I<output> argument. +If the I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input> +(cleartext) is encrypted in to the I<output> (ciphertext) using the +key_schedule specified by the I<schedule> argument, previously set via +I<DES_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now +ciphertext) is decrypted into the I<output> (now cleartext). Input +and output may overlap. DES_ecb_encrypt() does not return a value. + +DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using +three-key Triple-DES encryption in ECB mode. This involves encrypting +the input with I<ks1>, decrypting with the key schedule I<ks2>, and +then encrypting with I<ks3>. This routine greatly reduces the chances +of brute force breaking of DES and has the advantage of if I<ks1>, +I<ks2> and I<ks3> are the same, it is equivalent to just encryption +using ECB mode and I<ks1> as the key. + +The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES +encryption by using I<ks1> for the final encryption. + +DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining> +(CBC) mode of DES. If the I<encrypt> argument is non-zero, the +routine cipher-block-chain encrypts the cleartext data pointed to by +the I<input> argument into the ciphertext pointed to by the I<output> +argument, using the key schedule provided by the I<schedule> argument, +and initialization vector provided by the I<ivec> argument. If the +I<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. + +DES_xcbc_encrypt() is RSA's DESX mode of DES. It uses I<inw> and +I<outw> to 'whiten' the encryption. I<inw> and I<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. + +DES_ede3_cbc_encrypt() implements outer triple CBC DES encryption with +three keys. This means that each DES operation inside the CBC mode is +really an C<C=E(ks3,D(ks2,E(ks1,M)))>. This mode is used by SSL. + +The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by +reusing I<ks1> for the final encryption. C<C=E(ks1,D(ks2,E(ks1,M)))>. +This form of Triple-DES is used by the RSAREF library. + +DES_pcbc_encrypt() encrypt/decrypts using the propagating cipher block +chaining mode used by Kerberos v4. Its parameters are the same as +DES_ncbc_encrypt(). + +DES_cfb_encrypt() encrypt/decrypts using cipher feedback mode. This +method takes an array of characters as input and outputs and array of +characters. It does not require any padding to 8 character groups. +Note: the I<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 I<numbits>, this function is only +suggested for use when sending small numbers of characters. + +DES_cfb64_encrypt() +implements CFB mode of DES with 64bit feedback. Why is this +useful you ask? Because this routine will allow you to encrypt an +arbitrary number of bytes, no 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 :-). + +DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as +DES_cfb64_encrypt() except that Triple-DES is used. + +DES_ofb_encrypt() encrypts using output feedback mode. This method +takes an array of characters as input and outputs and array of +characters. It does not require any padding to 8 character groups. +Note: the I<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 numbits, this function is only +suggested for use when sending small numbers of characters. + +DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output +Feed Back mode. + +DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as +DES_ofb64_encrypt(), using Triple-DES. + +The following functions are included in the DES library for +compatibility with the MIT Kerberos library. + +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 I<output>. This function is +used by Kerberos v4. Other applications should use +L<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead. + +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 I<out_count>, 1, 2, 3 or 4 times. If I<output> is +non-NULL, the 8 bytes generated by each pass are written into +I<output>. + +The following are DES-based transformations: + +DES_fcrypt() is a fast version of the Unix crypt(3) function. This +version takes only a small amount of space relative to other fast +crypt() implementations. This is different to 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. This function +is thread safe, unlike the normal crypt. + +DES_crypt() is a faster replacement for the normal system crypt(). +This function calls DES_fcrypt() with a static array passed as the +third parameter. This emulates the normal non-thread safe semantics +of crypt(3). + +DES_enc_write() writes I<len> bytes to file descriptor I<fd> from +buffer I<buf>. The data is encrypted via I<pcbc_encrypt> (default) +using I<sched> for the key and I<iv> as a starting vector. The actual +data send down I<fd> consists of 4 bytes (in network byte order) +containing the length of the following encrypted data. The encrypted +data then follows, padded with random data out to a multiple of 8 +bytes. + +DES_enc_read() is used to read I<len> bytes from file descriptor +I<fd> into buffer I<buf>. The data being read from I<fd> is assumed to +have come from DES_enc_write() and is decrypted using I<sched> for +the key schedule and I<iv> for the initial vector. + +B<Warning:> The data format used by DES_enc_write() and DES_enc_read() +has a cryptographic weakness: When asked to write more than MAXWRITE +bytes, DES_enc_write() will split the data into several chunks that +are all encrypted using the same IV. So don't use these functions +unless you are sure you know what you do (in which case you might not +want to use them anyway). They cannot handle non-blocking sockets. +DES_enc_read() uses an internal state and thus cannot be used on +multiple files. + +I<DES_rw_mode> is used to specify the encryption mode to use with +DES_enc_read() and DES_end_write(). If set to I<DES_PCBC_MODE> (the +default), DES_pcbc_encrypt is used. If set to I<DES_CBC_MODE> +DES_cbc_encrypt is used. + +=head1 NOTES + +Single-key DES is insecure due to its short key size. ECB mode is +not suitable for most applications; see L<des_modes(7)|des_modes(7)>. + +The L<evp(3)|evp(3)> library provides higher-level encryption functions. + +=head1 BUGS + +DES_3cbc_encrypt() is flawed and must not be used in applications. + +DES_cbc_encrypt() does not modify B<ivec>; use DES_ncbc_encrypt() +instead. + +DES_cfb_encrypt() and 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 bytes input bytes apart things +get ugly! + +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 DES_string_to_2key(). + +=head1 CONFORMING TO + +ANSI X3.106 + +The B<des> library was written to be source code compatible with +the MIT Kerberos library. + +=head1 SEE ALSO + +crypt(3), L<des_modes(7)|des_modes(7)>, L<evp(3)|evp(3)>, L<rand(3)|rand(3)> + +=head1 HISTORY + +In OpenSSL 0.9.7, all des_ functions were renamed to DES_ to avoid +clashes with older versions of libdes. Compatibility des_ functions +are provided for a short while, as well as crypt(). +Declarations for these are in <openssl/des_old.h>. There is no DES_ +variant for des_random_seed(). +This will happen to other functions +as well if they are deemed redundant (des_random_seed() just calls +RAND_seed() and is present for backward compatibility only), buggy or +already scheduled for removal. + +des_cbc_cksum(), des_cbc_encrypt(), des_ecb_encrypt(), +des_is_weak_key(), des_key_sched(), des_pcbc_encrypt(), +des_quad_cksum(), des_random_key() and des_string_to_key() +are available in the MIT Kerberos library; +des_check_key_parity(), des_fixup_key_parity() and des_is_weak_key() +are available in newer versions of that library. + +des_set_key_checked() and des_set_key_unchecked() were added in +OpenSSL 0.9.5. + +des_generate_random_block(), des_init_random_number_generator(), +des_new_random_key(), des_set_random_generator_seed() and +des_set_sequence_number() and des_rand_data() are used in newer +versions of Kerberos but are not implemented here. + +des_random_key() generated cryptographically weak random data in +SSLeay and in OpenSSL prior version 0.9.5, as well as in the original +MIT library. + +=head1 AUTHOR + +Eric Young (eay@cryptsoft.com). Modified for the OpenSSL project +(http://www.openssl.org). + +=cut |