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Annotation of rsaref/source/md2c.c, revision 1.1

1.1     ! root        1: /* MD2C.C - RSA Data Security, Inc., MD2 message-digest algorithm
        !             2:  */
        !             3: 
        !             4: /* Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.
        !             5: 
        !             6:    License to copy and use this software is granted for
        !             7:    non-commercial Internet Privacy-Enhanced Mail provided that it is
        !             8:    identified as the "RSA Data Security, Inc. MD2 Message Digest
        !             9:    Algorithm" in all material mentioning or referencing this software
        !            10:    or this function.
        !            11: 
        !            12:    RSA Data Security, Inc. makes no representations concerning either
        !            13:    the merchantability of this software or the suitability of this
        !            14:    software for any particular purpose. It is provided "as is"
        !            15:    without express or implied warranty of any kind.
        !            16: 
        !            17:    These notices must be retained in any copies of any part of this
        !            18:    documentation and/or software.  
        !            19:  */
        !            20: 
        !            21: #include "global.h"
        !            22: #include "md2.h"
        !            23: 
        !            24: static void MD2Transform PROTO_LIST
        !            25:   ((unsigned char [16], unsigned char [16], unsigned char [16]));
        !            26: static void MD2_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
        !            27: static void MD2_memset PROTO_LIST ((POINTER, int, unsigned int));
        !            28: 
        !            29: /* Permutation of 0..255 constructed from the digits of pi. It gives a
        !            30:    "random" nonlinear byte substitution operation.
        !            31:  */
        !            32: static unsigned char PI_SUBST[256] = {
        !            33:   41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
        !            34:   19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
        !            35:   76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
        !            36:   138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
        !            37:   245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
        !            38:   148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
        !            39:   39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
        !            40:   181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
        !            41:   150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
        !            42:   112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
        !            43:   96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
        !            44:   85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
        !            45:   234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
        !            46:   129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
        !            47:   8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
        !            48:   203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
        !            49:   166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
        !            50:   31, 26, 219, 153, 141, 51, 159, 17, 131, 20
        !            51: };
        !            52: 
        !            53: static unsigned char *PADDING[] = {
        !            54:   (unsigned char *)"", (unsigned char *)"\001", (unsigned char *)"\002\002",
        !            55:   (unsigned char *)"\003\003\003", (unsigned char *)"\004\004\004\004",
        !            56:   (unsigned char *)"\005\005\005\005\005",
        !            57:   (unsigned char *)"\006\006\006\006\006\006", 
        !            58:   (unsigned char *)"\007\007\007\007\007\007\007",
        !            59:   (unsigned char *)"\010\010\010\010\010\010\010\010",
        !            60:   (unsigned char *)"\011\011\011\011\011\011\011\011\011",
        !            61:   (unsigned char *)"\012\012\012\012\012\012\012\012\012\012",
        !            62:   (unsigned char *)"\013\013\013\013\013\013\013\013\013\013\013",
        !            63:   (unsigned char *)"\014\014\014\014\014\014\014\014\014\014\014\014",
        !            64:   (unsigned char *)"\015\015\015\015\015\015\015\015\015\015\015\015\015",
        !            65:   (unsigned char *)"\016\016\016\016\016\016\016\016\016\016\016\016\016\016",
        !            66:   (unsigned char *)
        !            67:     "\017\017\017\017\017\017\017\017\017\017\017\017\017\017\017",
        !            68:   (unsigned char *)
        !            69:     "\020\020\020\020\020\020\020\020\020\020\020\020\020\020\020\020"
        !            70: };
        !            71: 
        !            72: /* MD2 initialization. Begins an MD2 operation, writing a new context.
        !            73:  */
        !            74: void MD2Init (context)
        !            75: MD2_CTX *context;                                                /* context */
        !            76: {
        !            77:   context->count = 0;
        !            78:   MD2_memset ((POINTER)context->state, 0, sizeof (context->state));
        !            79:   MD2_memset ((POINTER)context->checksum, 0, sizeof (context->checksum));
        !            80: }
        !            81: 
        !            82: /* MD2 block update operation. Continues an MD2 message-digest operation,
        !            83:    processing another message block, and updating the context.
        !            84:  */
        !            85: void MD2Update (context, input, inputLen)
        !            86: MD2_CTX *context;                                                /* context */
        !            87: unsigned char *input;                                        /* input block */
        !            88: unsigned int inputLen;                             /* length of input block */
        !            89: {
        !            90:   unsigned int i, index, partLen;
        !            91:   
        !            92:   /* Update number of bytes mod 16 */
        !            93:   index = context->count;
        !            94:   context->count = (index + inputLen) & 0xf;
        !            95:   
        !            96:   partLen = 16 - index;
        !            97:   
        !            98:   /* Transform as many times as possible.
        !            99:     */
        !           100:   if (inputLen >= partLen) {
        !           101:     MD2_memcpy ((POINTER)&context->buffer[index], (POINTER)input, partLen);
        !           102:     MD2Transform (context->state, context->checksum, context->buffer);
        !           103: 
        !           104:     for (i = partLen; i + 15 < inputLen; i += 16)
        !           105:       MD2Transform (context->state, context->checksum, &input[i]);
        !           106:     
        !           107:     index = 0;
        !           108:   }
        !           109:   else
        !           110:     i = 0;
        !           111:   
        !           112:   /* Buffer remaining input */
        !           113:   MD2_memcpy
        !           114:     ((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
        !           115: }
        !           116: 
        !           117: /* MD2 finalization. Ends an MD2 message-digest operation, writing the
        !           118:      message digest and zeroizing the context.
        !           119:  */
        !           120: void MD2Final (digest, context)
        !           121: unsigned char digest[16];                                 /* message digest */
        !           122: MD2_CTX *context;                                                /* context */
        !           123: {
        !           124:   unsigned int index, padLen;
        !           125: 
        !           126:   /* Pad out to multiple of 16.
        !           127:    */
        !           128:   index = context->count;
        !           129:   padLen = 16 - index;
        !           130:   MD2Update (context, PADDING[padLen], padLen);
        !           131: 
        !           132:   /* Extend with checksum */
        !           133:   MD2Update (context, context->checksum, 16);
        !           134:   
        !           135:   /* Store state in digest */
        !           136:   MD2_memcpy ((POINTER)digest, (POINTER)context->state, 16);
        !           137:   
        !           138:   /* Zeroize sensitive information.
        !           139:    */
        !           140:   MD2_memset ((POINTER)context, 0, sizeof (*context));
        !           141: }
        !           142: 
        !           143: /* MD2 basic transformation. Transforms state and updates checksum
        !           144:      based on block.
        !           145:  */
        !           146: static void MD2Transform (state, checksum, block)
        !           147: unsigned char state[16];
        !           148: unsigned char checksum[16];
        !           149: unsigned char block[16];
        !           150: {
        !           151:   unsigned int i, j, t;
        !           152:   unsigned char x[48];
        !           153:   
        !           154:   /* Form encryption block from state, block, state ^ block.
        !           155:    */
        !           156:   for (i = 0; i < 16; i++) {
        !           157:     x[i] = state[i];
        !           158:     x[i+16] = block[i];
        !           159:     x[i+32] = state[i] ^ block[i];
        !           160:   }
        !           161:   
        !           162:   /* Encrypt block (18 rounds).
        !           163:    */
        !           164:   t = 0;
        !           165:   for (i = 0; i < 18; i++) {
        !           166:     for (j = 0; j < 48; j++)
        !           167:       t = x[j] ^= PI_SUBST[t];
        !           168:     t = (t + i) & 0xff;
        !           169:   }
        !           170:     
        !           171:   /* Save new state */
        !           172:   for (i = 0; i < 16; i++)
        !           173:     state[i] = x[i];
        !           174:     
        !           175:   /* Update checksum.
        !           176:    */
        !           177:   t = checksum[15];
        !           178:   for (i = 0; i < 16; i++)
        !           179:     t = checksum[i] ^= PI_SUBST[block[i] ^ t];
        !           180: 
        !           181:   /* Zeroize sensitive information.
        !           182:    */
        !           183:   MD2_memset ((POINTER)x, 0, sizeof (x));
        !           184: }
        !           185: 
        !           186: /* Note: Replace "for loop" with standard memcpy if possible.
        !           187:  */
        !           188: static void MD2_memcpy (output, input, len)
        !           189: POINTER output;
        !           190: POINTER input;
        !           191: unsigned int len;
        !           192: {
        !           193:   unsigned int i;
        !           194:   
        !           195:   for (i = 0; i < len; i++)
        !           196:     output[i] = input[i];
        !           197: }
        !           198: 
        !           199: /* Note: Replace "for loop" with standard memset if possible.
        !           200:  */
        !           201: static void MD2_memset (output, value, len)
        !           202: POINTER output;
        !           203: int value;
        !           204: unsigned int len;
        !           205: {
        !           206:   unsigned int i;
        !           207:   
        !           208:   for (i = 0; i < len; i++)
        !           209:     ((char *)output)[i] = (char)value;
        !           210: }

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