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Annotation of 43BSDReno/kerberosIV/des/cbc_encrypt.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * $Source: /afs/athena.mit.edu/astaff/project/kerberos/src/lib/des/RCS/cbc_encrypt.c,v $
        !             3:  * $Author: jtkohl $
        !             4:  *
        !             5:  * Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute
        !             6:  * of Technology.
        !             7:  *
        !             8:  * For copying and distribution information, please see the file
        !             9:  * <mit-copyright.h>.
        !            10:  *
        !            11:  * These routines perform encryption and decryption using the DES
        !            12:  * private key algorithm, or else a subset of it -- fewer inner loops.
        !            13:  * (AUTH_DES_ITER defaults to 16, may be less.)
        !            14:  *
        !            15:  * Under U.S. law, this software may not be exported outside the US
        !            16:  * without license from the U.S. Commerce department.
        !            17:  *
        !            18:  * These routines form the library interface to the DES facilities.
        !            19:  *
        !            20:  * Originally written 8/85 by Steve Miller, MIT Project Athena.
        !            21:  */
        !            22: 
        !            23: #ifndef        lint
        !            24: static char rcsid_cbc_encrypt_c[] =
        !            25: "$Id: cbc_encrypt.c,v 4.10 90/01/02 13:46:14 jtkohl Exp $";
        !            26: #endif lint
        !            27: 
        !            28: #include <mit-copyright.h>
        !            29: #include <stdio.h>
        !            30: #include <des.h>
        !            31: 
        !            32: extern int des_debug;
        !            33: extern int des_debug_print();
        !            34: 
        !            35: /*
        !            36:  * This routine performs DES cipher-block-chaining operation, either
        !            37:  * encrypting from cleartext to ciphertext, if encrypt != 0 or
        !            38:  * decrypting from ciphertext to cleartext, if encrypt == 0.
        !            39:  *
        !            40:  * The key schedule is passed as an arg, as well as the cleartext or
        !            41:  * ciphertext. The cleartext and ciphertext should be in host order.
        !            42:  *
        !            43:  * NOTE-- the output is ALWAYS an multiple of 8 bytes long.  If not
        !            44:  * enough space was provided, your program will get trashed.
        !            45:  *
        !            46:  * For encryption, the cleartext string is null padded, at the end, to
        !            47:  * an integral multiple of eight bytes.
        !            48:  *
        !            49:  * For decryption, the ciphertext will be used in integral multiples
        !            50:  * of 8 bytes, but only the first "length" bytes returned into the
        !            51:  * cleartext.
        !            52:  */
        !            53: 
        !            54: int
        !            55: des_cbc_encrypt(in,out,length,key,iv,encrypt)
        !            56:     des_cblock *in;            /* >= length bytes of input text */
        !            57:     des_cblock *out;           /* >= length bytes of output text */
        !            58:     register long length;      /* in bytes */
        !            59:     int encrypt;               /* 0 ==> decrypt, else encrypt */
        !            60:     des_key_schedule key;              /* precomputed key schedule */
        !            61:     des_cblock *iv;            /* 8 bytes of ivec */
        !            62: {
        !            63:     register unsigned long *input = (unsigned long *) in;
        !            64:     register unsigned long *output = (unsigned long *) out;
        !            65:     register unsigned long *ivec = (unsigned long *) iv;
        !            66: 
        !            67:     unsigned long i,j;
        !            68:     static unsigned long t_input[2];
        !            69:     static unsigned long t_output[2];
        !            70:     static unsigned char *t_in_p;
        !            71:     static unsigned long xor_0, xor_1;
        !            72: 
        !            73:     t_in_p = (unsigned char *) t_input;
        !            74:     if (encrypt) {
        !            75: #ifdef MUSTALIGN
        !            76:        if ((long) ivec & 3) {
        !            77:            bcopy((char *)ivec++, (char *)&t_output[0], sizeof(t_output[0]));
        !            78:            bcopy((char *)ivec, (char *)&t_output[1], sizeof(t_output[1]));
        !            79:        }
        !            80:        else
        !            81: #endif
        !            82:        {
        !            83:            t_output[0] = *ivec++;
        !            84:            t_output[1] = *ivec;
        !            85:        }
        !            86: 
        !            87:        for (i = 0; length > 0; i++, length -= 8) {
        !            88:            /* get input */
        !            89: #ifdef MUSTALIGN
        !            90:            if ((long) input & 3) {
        !            91:                bcopy((char *)input++,(char *)&t_input[0],sizeof(t_input[0]));
        !            92:                bcopy((char *)input++,(char *)&t_input[1],sizeof(t_input[1]));
        !            93:            }
        !            94:            else
        !            95: #endif
        !            96:            {
        !            97:                t_input[0] = *input++;
        !            98:                t_input[1] = *input++;
        !            99:            }
        !           100: 
        !           101:            /* zero pad */
        !           102:            if (length < 8)
        !           103:                for (j = length; j <= 7; j++)
        !           104:                    *(t_in_p+j)= 0;
        !           105: 
        !           106: #ifdef DEBUG
        !           107:            if (des_debug)
        !           108:                des_debug_print("clear",length,t_input[0],t_input[1]);
        !           109: #endif
        !           110:            /* do the xor for cbc into the temp */
        !           111:            t_input[0] ^= t_output[0];
        !           112:            t_input[1] ^= t_output[1];
        !           113:            /* encrypt */
        !           114:            (void) des_ecb_encrypt(t_input,t_output,key,encrypt);
        !           115:            /* copy temp output and save it for cbc */
        !           116: #ifdef MUSTALIGN
        !           117:            if ((long) output & 3) {
        !           118:                bcopy((char *)&t_output[0],(char *)output++,
        !           119:                      sizeof(t_output[0]));
        !           120:                bcopy((char *)&t_output[1],(char *)output++,
        !           121:                      sizeof(t_output[1]));
        !           122:            }
        !           123:            else
        !           124: #endif
        !           125:            {
        !           126:                *output++ = t_output[0];
        !           127:                *output++ = t_output[1];
        !           128:            }
        !           129: 
        !           130: #ifdef DEBUG
        !           131:            if (des_debug) {
        !           132:                des_debug_print("xor'ed",i,t_input[0],t_input[1]);
        !           133:                des_debug_print("cipher",i,t_output[0],t_output[1]);
        !           134:            }
        !           135: #endif
        !           136:        }
        !           137:        return 0;
        !           138:     }
        !           139: 
        !           140:     else {
        !           141:        /* decrypt */
        !           142: #ifdef MUSTALIGN
        !           143:        if ((long) ivec & 3) {
        !           144:            bcopy((char *)ivec++,(char *)&xor_0,sizeof(xor_0));
        !           145:            bcopy((char *)ivec,(char *)&xor_1,sizeof(xor_1));
        !           146:        }
        !           147:        else
        !           148: #endif
        !           149:        {
        !           150:            xor_0 = *ivec++;
        !           151:            xor_1 = *ivec;
        !           152:        }
        !           153: 
        !           154:        for (i = 0; length > 0; i++, length -= 8) {
        !           155:            /* get input */
        !           156: #ifdef MUSTALIGN
        !           157:            if ((long) input & 3) {
        !           158:                bcopy((char *)input++,(char *)&t_input[0],sizeof(t_input[0]));
        !           159:                bcopy((char *)input++,(char *)&t_input[1],sizeof(t_input[0]));
        !           160:            }
        !           161:            else
        !           162: #endif
        !           163:            {
        !           164:                t_input[0] = *input++;
        !           165:                t_input[1] = *input++;
        !           166:            }
        !           167: 
        !           168:            /* no padding for decrypt */
        !           169: #ifdef DEBUG
        !           170:            if (des_debug)
        !           171:                des_debug_print("cipher",i,t_input[0],t_input[1]);
        !           172: #else
        !           173: #ifdef lint
        !           174:            i = i;
        !           175: #endif
        !           176: #endif
        !           177:            /* encrypt */
        !           178:            (void) des_ecb_encrypt(t_input,t_output,key,encrypt);
        !           179: #ifdef DEBUG
        !           180:            if (des_debug)
        !           181:                des_debug_print("out pre xor",i,t_output[0],t_output[1]);
        !           182: #endif
        !           183:            /* do the xor for cbc into the output */
        !           184:            t_output[0] ^= xor_0;
        !           185:            t_output[1] ^= xor_1;
        !           186:            /* copy temp output */
        !           187: #ifdef MUSTALIGN
        !           188:            if ((long) output & 3) {
        !           189:                bcopy((char *)&t_output[0],(char *)output++,
        !           190:                      sizeof(t_output[0]));
        !           191:                bcopy((char *)&t_output[1],(char *)output++,
        !           192:                      sizeof(t_output[1]));
        !           193:            }
        !           194:            else
        !           195: #endif
        !           196:            {
        !           197:                *output++ = t_output[0];
        !           198:                *output++ = t_output[1];
        !           199:            }
        !           200: 
        !           201:            /* save xor value for next round */
        !           202:            xor_0 = t_input[0];
        !           203:            xor_1 = t_input[1];
        !           204: #ifdef DEBUG
        !           205:            if (des_debug)
        !           206:                des_debug_print("clear",i,t_output[0],t_output[1]);
        !           207: #endif
        !           208:        }
        !           209:        return 0;
        !           210:     }
        !           211: }

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