Cryptography Reference
In-Depth Information
Ta b l e 8 . 4
The Elements of Table
T
Employed by the MD5 Hash Function
T
[1]=
0xD76AA478
T
[17]=
0xF61E2562
T
[33]=
0xFFFA3942
T
[49]=
0xF4292244
T
[2]=
0xE8C7B756
T
[18]=
0xC040B340
T
[34]=
0x8771F681
T
[50]=
0x432AFF97
T
[3]=
0x242070DB
T
[19]=
0x265E5A51
T
[35]=
0x6D9D6122
T
[51]=
0xAB9423A7
T
[4]=
0xC1BDCEEE
T
[20]=
0xE9B6C7AA
T
[36]=
0xFDE5380C
T
[52]=
0xFC93A039
T
[5]=
0xF57C0FAF
T
[21]=
0xD62F105D
T
[37]=
0xA4BEEA44
T
[53]=
0x655B59C3
T
[6]=
0x4787C62A
T
[22]=
0x02441453
T
[38]=
0x4BDECFA9
T
[54]=
0x8F0CCC92
T
[7]=
0xA8304613
T
[23]=
0xD8A1E681
T
[39]=
0xF6BB4B60
T
[55]=
0xFFEFF47D
T
[8]=
0xFD469501
T
[24]=
0xE7D3FBC8
T
[40]=
0xBEBFBC70
T
[56]=
0x85845DD1
T
[9]=
0x698098D8
T
[25]=
0x21E1CDE6
T
[41]=
0x289B7EC6
T
[57]=
0x6FA87E4F
T
[10]=
0x8B44F7AF
T
[26]=
0xC33707D6
T
[42]=
0xEAA127FA
T
[58]=
0xFE2CE6E0
T
[11]=
0xFFFF5BB1
T
[27]=
0xF4D50D87
T
[43]=
0xD4EF3085
T
[59]=
0xA3014314
T
[12]=
0x895CD7BE
T
[28]=
0x455A14ED
T
[44]=
0x04881D05
T
[60]=
0x4E0811A1
T
[13]=
0x6B901122
T
[29]=
0xA9E3E905
T
[45]=
0xD9D4D039
T
[61]=
0xF7537E82
T
[14]=
0xFD987193
T
[30]=
0xFCEFA3F8
T
[46]=
0xE6DB99E5
T
[62]=
0xBD3AF235
T
[15]=
0xA679438E
T
[31]=
0x676F02D9
T
[47]=
0x1FA27CF8
T
[63]=
0x2AD7D2BB
T
[16]=
0x49B40821
T
[32]=
0x8D2A4C8A
T
[48]=
0xC4AC5665
T
[64]=
0xEB86D391
In addition to
f
t
and
K
t
, there is a message schedule
W
that comprises eighty
32-bit words. The schedule is initialized as follows:
W
t
=
M
[
t
]
0
≤
t
≤
15
(
W
t−
3
⊕
W
t−
8
⊕
W
t−
14
⊕
W
t−
16
)
←
116
≤
t
≤
79
After preprocessing is completed, the message is hashed iteratively using
Algorithm 8.10. First, the five registers are initialized (the first four registers are
indentically initialized as in the case of MD4, and the fifth register is initialized
with
0xC3D2E1F0
). Afterwards, each message block
M
[1],
M
[1], ...,
M
[
N
] is
processed iteratively, where the result of each iteration is used in the next iteration.
Finally, the result is the concatenation of the values of the five registers. It is a 160-bit
hash value that may serve as message digest for message
m
.
From a security viewpoint, there are two remarks to make at this point:
•
First, a SHA-1 hash value is 32 bits longer than an MD5 hash value. This
is advantageous, because it means that SHA-1 is potentially more resistant
against brute-force attacks. This is even more true for the SHA variants
itemized in Table 8.1.
