bug fixed in md5-asm.S ( wrong values for length_b%512=505..511 )

diff --git a/md5-asm.S b/md5-asm.S
index 469f9ab7535e56efdf255c739fb09e6b4df44547..de3b170092330281674357475131a58019413d22 100644 (file)
--- a/md5-asm.S
+++ b/md5-asm.S
@@ -785,6 +785,7 @@ md5_lastBlock:
        movw r16, r20 /* length_b  */ 
        movw r14, r22 /* block_ptr */
        movw r12, r24 /* state_ptr */
+       ldi r18, 64
 2:
        cpi r17, 2 /* hi8(512) */       
        brlo 2f
@@ -792,7 +793,6 @@ md5_lastBlock:
        movw r24, r12
        movw r22, r14
        rcall md5_nextBlock
-       ldi r18, 64
        add r14, r18
        adc r15, r1
        subi r17, 2
@@ -801,58 +801,59 @@ md5_lastBlock:
        pop r31
        pop r30
 
-       adiw r30, 1
+       adiw r30, 1 /* adjust Z to point to buffer */
        movw r26, r14
        movw r24, r16
        adiw r24, 7
 
        lsr r25
        ror r24
-       lsr r24
+       lsr r25
+       ror r24
        lsr r24 /* r24 now holds how many bytes are to copy */
-       ldi r18, 64
-       sub r18, r24
+    ldi r18, 64
+       sub r18, r24 /* r18 will hold the amount of used bytes in buffer */
        tst r24
 4:
        breq 5f
        ld r0, X+
-       st Z+, r0
+       st Z+, r0 
        dec r24
-       rjmp 4b
+       rjmp 4b /* Z points to the byte after msg in buffer */
 5:     /* append 1-bit */
        mov r20, r16
+       ldi r19, 0x80
        andi r20, 0x07
        brne bit_fucking
-       ldi r19, 0x80
        st Z+, r19
-       dec r18
+       dec r18 /* 'allocate' another byte in buffer */
        rjmp after_bit_fucking
 bit_fucking:
-       ldi r19, 0x80
 1:
        lsr r19
        dec r20
        brne 1b
        or r0, r19
        st -Z, r0
-       adiw r30, 1
+    adiw r30, 1
 after_bit_fucking:
        clt     
        cpi r18, 8
        brmi 2f
-       set         /* store in t if the counter will also fit in this block */
+       set         /* store in t if the counter will also fit in this block (1 if fit)*/
 2:
        tst r18
        breq 2f
-1:
+1: /* fill remaning buffer with zeros */
        st Z+, r1
        dec r18
        brne 1b
 2:
        sbiw r30, 63
        sbiw r30,  1
-       movw r14, r30   
+       movw r14, r30 /* r14:r15 now points to buffer */        
        brts load_counter
+       /* counter does not fit, finalize this block */
        movw r24, r12
        movw r22, r14
        rcall md5_nextBlock
@@ -864,13 +865,14 @@ after_bit_fucking:
        brne 3b
        
 load_counter:          
-       movw r26, r12
+       movw r26, r12 /* X points to state */
        adiw r26, 16
        ld r19, X+
        ld r20, X+
        ld r21, X+
        ld r22, X+
-       brts post_counter_decrement     
+       brts post_counter_decrement     /* do not decremen because counter fits */
+counter_decrement:
        subi r19, 1
        sbci r20, 0
        sbci r21, 0
@@ -883,8 +885,8 @@ post_counter_decrement:
        rol r21
        rol r22
        rol r23
-       add r18, r16
-       adc r19, r17
+       mov r18, r16 /* r16:r17 length_b */
+       add r19, r17
        adc r20, r1
        adc r21, r1
        adc r22, r1

diff --git a/md5.c b/md5.c
index ddad0b9a03af0a933142fc0aa7932679c3d42cd6..20ec519c961a9152c235d8653351da9d0bbbee20 100644 (file)
--- a/md5.c
+++ b/md5.c
@@ -80,7 +80,8 @@ void md5_core(uint32_t* a, void* block, uint8_t as, uint8_t s, uint8_t i, uint8_
        uart_hexdump(&s, 1); uart_putc(' ');
        uart_hexdump(&i, 1); uart_putc(']');
 #endif 
-       t = a[as] + funcs[fi](a[(as+1)&3], a[(as+2)&3], a[(as+3)&3]) + *((uint32_t*)block) + md5_T[i] ;
+       t = a[as] + funcs[fi](a[(as+1)&3], a[(as+2)&3], a[(as+3)&3]) 
+           + *((uint32_t*)block) + pgm_read_dword(md5_T+i) ;
        a[as]=a[(as+1)&3] + ROTL32(t, s);
 }
 

diff --git a/md5_sbox.h b/md5_sbox.h
index b8ab6361c9bd985c527c5db1181bd135d28b4224..597b3db412adae35e9895dce99665a314b3e9e9b 100644 (file)
--- a/md5_sbox.h
+++ b/md5_sbox.h
@@ -19,7 +19,10 @@
 #ifndef MD5_SBOX_H_
 #define MD5_SBOX_H_
 
-uint32_t md5_T[]={
+#include <stdint.h>
+#include <avr/pgmspace.h>
+
+uint32_t md5_T[] PROGMEM = {
        0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 
        0x4787c62a, 0xa8304613, 0xfd469501, 0x698098d8, 0x8b44f7af, 
        0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 
@@ -32,6 +35,6 @@ uint32_t md5_T[]={
        0xe6db99e5, 0x1fa27cf8, 0xc4ac5665, 0xf4292244, 0x432aff97, 
        0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 
        0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 
-       0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391};
+       0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391 };
 
 #endif /*MD5_SBOX_H_*/

diff --git a/test_src/main-md5-test.c b/test_src/main-md5-test.c
index 1ede35338319125983d2082df984b882abbb67ca..90c5971abd1597de3c1e464ebc62d6fe979cd29b 100644 (file)
--- a/test_src/main-md5-test.c
+++ b/test_src/main-md5-test.c
@@ -93,15 +93,26 @@ void testrun_md5(void){
                "abcdefghijklmnopqrstuvwxyz", 
                "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 
                "12345678901234567890123456789012345678901234567890123456789012345678901234567890"};
-       uint8_t i;
+       uint16_t i;
        
        uart_putstr("\r\n=== MD5 test suit ===");
        for(i=0; i<7; ++i){
-               uart_putstr("\r\n MD5 (\"");
-               uart_putstr(testv[i]);
-               uart_putstr("\") = \r\n\t");
+               cli_putstr("\r\n MD5 (\"");
+               cli_putstr(testv[i]);
+               cli_putstr("\") = \r\n\t");
                md5(&hash, testv[i], strlen(testv[i])*8);
-               uart_hexdump(hash, 16);
+               cli_hexdump(hash, 16);
+       }
+       uint8_t buffer[512/8];
+       char str[5];
+       for(i=505; i<512; ++i){
+               memset(buffer, 0, 512/8);
+               cli_putstr_P(PSTR("\r\nMD5("));
+               utoa(i, str, 10);
+               cli_putstr(str);
+               cli_putstr_P(PSTR(" zero bits) = "));
+               md5(&hash, buffer, i);
+               cli_hexdump(hash, 16);
        }
 }