/* * $Source: /afs/athena.mit.edu/astaff/project/kerberos/src/lib/des/RCS/cbc_encrypt.c,v $ * $Author: jtkohl $ * * Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute * of Technology. * * For copying and distribution information, please see the file * <mit-copyright.h>. * * These routines perform encryption and decryption using the DES * private key algorithm, or else a subset of it -- fewer inner loops. * (AUTH_DES_ITER defaults to 16, may be less.) * * Under U.S. law, this software may not be exported outside the US * without license from the U.S. Commerce department. * * These routines form the library interface to the DES facilities. * * Originally written 8/85 by Steve Miller, MIT Project Athena. */ #ifndef lint static char rcsid_cbc_encrypt_c[] = "$Id: cbc_encrypt.c,v 4.10 90/01/02 13:46:14 jtkohl Exp $"; #endif lint #include <mit-copyright.h> #include <stdio.h> #include <des.h> extern int des_debug; extern int des_debug_print(); /* * This routine performs DES cipher-block-chaining operation, either * encrypting from cleartext to ciphertext, if encrypt != 0 or * decrypting from ciphertext to cleartext, if encrypt == 0. * * The key schedule is passed as an arg, as well as the cleartext or * ciphertext. The cleartext and ciphertext should be in host order. * * NOTE-- the output is ALWAYS an multiple of 8 bytes long. If not * enough space was provided, your program will get trashed. * * For encryption, the cleartext string is null padded, at the end, to * an integral multiple of eight bytes. * * For decryption, the ciphertext will be used in integral multiples * of 8 bytes, but only the first "length" bytes returned into the * cleartext. */ int des_cbc_encrypt(in,out,length,key,iv,encrypt) des_cblock *in; /* >= length bytes of input text */ des_cblock *out; /* >= length bytes of output text */ register long length; /* in bytes */ int encrypt; /* 0 ==> decrypt, else encrypt */ des_key_schedule key; /* precomputed key schedule */ des_cblock *iv; /* 8 bytes of ivec */ { register unsigned long *input = (unsigned long *) in; register unsigned long *output = (unsigned long *) out; register unsigned long *ivec = (unsigned long *) iv; unsigned long i,j; static unsigned long t_input[2]; static unsigned long t_output[2]; static unsigned char *t_in_p; static unsigned long xor_0, xor_1; t_in_p = (unsigned char *) t_input; if (encrypt) { #ifdef MUSTALIGN if ((long) ivec & 3) { bcopy((char *)ivec++, (char *)&t_output[0], sizeof(t_output[0])); bcopy((char *)ivec, (char *)&t_output[1], sizeof(t_output[1])); } else #endif { t_output[0] = *ivec++; t_output[1] = *ivec; } for (i = 0; length > 0; i++, length -= 8) { /* get input */ #ifdef MUSTALIGN if ((long) input & 3) { bcopy((char *)input++,(char *)&t_input[0],sizeof(t_input[0])); bcopy((char *)input++,(char *)&t_input[1],sizeof(t_input[1])); } else #endif { t_input[0] = *input++; t_input[1] = *input++; } /* zero pad */ if (length < 8) for (j = length; j <= 7; j++) *(t_in_p+j)= 0; #ifdef DEBUG if (des_debug) des_debug_print("clear",length,t_input[0],t_input[1]); #endif /* do the xor for cbc into the temp */ t_input[0] ^= t_output[0]; t_input[1] ^= t_output[1]; /* encrypt */ (void) des_ecb_encrypt(t_input,t_output,key,encrypt); /* copy temp output and save it for cbc */ #ifdef MUSTALIGN if ((long) output & 3) { bcopy((char *)&t_output[0],(char *)output++, sizeof(t_output[0])); bcopy((char *)&t_output[1],(char *)output++, sizeof(t_output[1])); } else #endif { *output++ = t_output[0]; *output++ = t_output[1]; } #ifdef DEBUG if (des_debug) { des_debug_print("xor'ed",i,t_input[0],t_input[1]); des_debug_print("cipher",i,t_output[0],t_output[1]); } #endif } return 0; } else { /* decrypt */ #ifdef MUSTALIGN if ((long) ivec & 3) { bcopy((char *)ivec++,(char *)&xor_0,sizeof(xor_0)); bcopy((char *)ivec,(char *)&xor_1,sizeof(xor_1)); } else #endif { xor_0 = *ivec++; xor_1 = *ivec; } for (i = 0; length > 0; i++, length -= 8) { /* get input */ #ifdef MUSTALIGN if ((long) input & 3) { bcopy((char *)input++,(char *)&t_input[0],sizeof(t_input[0])); bcopy((char *)input++,(char *)&t_input[1],sizeof(t_input[0])); } else #endif { t_input[0] = *input++; t_input[1] = *input++; } /* no padding for decrypt */ #ifdef DEBUG if (des_debug) des_debug_print("cipher",i,t_input[0],t_input[1]); #else #ifdef lint i = i; #endif #endif /* encrypt */ (void) des_ecb_encrypt(t_input,t_output,key,encrypt); #ifdef DEBUG if (des_debug) des_debug_print("out pre xor",i,t_output[0],t_output[1]); #endif /* do the xor for cbc into the output */ t_output[0] ^= xor_0; t_output[1] ^= xor_1; /* copy temp output */ #ifdef MUSTALIGN if ((long) output & 3) { bcopy((char *)&t_output[0],(char *)output++, sizeof(t_output[0])); bcopy((char *)&t_output[1],(char *)output++, sizeof(t_output[1])); } else #endif { *output++ = t_output[0]; *output++ = t_output[1]; } /* save xor value for next round */ xor_0 = t_input[0]; xor_1 = t_input[1]; #ifdef DEBUG if (des_debug) des_debug_print("clear",i,t_output[0],t_output[1]); #endif } return 0; } }