Security Considerations
94 RSA BSAFE Crypto-C Developer’s Guide
Initialization Vectors and Salts
Although IVs and salts are not secret information, it is still a good idea to use random
values. If a salt is not random, an attacker will have much fewer precomputations to
make in generating keys from possible password/salt combinations.
An IV shou ld also be used for onl y one me ssage. Using th e same I V with t he same key
on two separate messages may provide an attacker with useful information.
DES Weak Keys
Researchers over the years have found that some DES keys are more susceptible to
attack than others. Some of these keys are known as “weak”; others, when used in
pairs, are called “semi-weak.” Using a weak key or a semi-weak pair may not
necessarily pose a security risk; it could depend on the mode of DES. However, it is
simply easier to avoid these keys (listed in Table 3-3) altogether.
Table 3-3 DES Weak and Semi-Weak Keys
0101010101010101
FEFEFEFEFEFEFEFE
1F1F1F1F1F1F1F1F
E0E0E0E0E0E0E0E0
01FE01FE01FE01FE
1FE01FE00EF10EF1
01E001E001F101F1
1FFE1FFE0EFE0EFE
011F011F010E010E
E0FEE0FEF1FEF1FE
FE01FE01FE01FE01
E01FE01FF10EF10E
E001E001F101F101
FE1FFE1FFE0EFE0E
1F011F010E010E01
FEE0FEE0FEF1FEF1