Construct a BER file without a public key to cause the system to crash.
In January 25, 2016, Wade Mealing sent an email to the OSS Security and CVE certification departments. The electronic topic is: constructing a special key file to cause DoS on the host. He wrote in the email:
Hello,
I hope the relevant departments can assign a CVE number to the following questions:
I have analyzed and researched the ASN1.1 DER decoder, and found that you only need to construct a special key file, we can
Problem descriptionThe topic is simple, give n numbers, do not change their relative position, in the middle add K multiplication sign and n-k-1 a plus, (parentheses arbitrarily add) to make the final result as large as possible. Because multiplication sign and the plus sign are all N-1, there is a sign between each of the two adjacent numbers. For example:n=5,k=2,5 numbers are 1, 2, 3, 4, 5, respectively, can be added:1*2* (3+4+5) =241* (2+3) * (4+5) =45(1*2+3) * (4+5) =45......Input formatTher
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password is encrypted, we need to verify the password to determine whether the password entered by the user is correct:
Easy to use.Password_verifyWe can verify the previously encrypted string (in the database.
However, if we sometimes need to change our encryption method, for example, if one day we suddenly want to change the salt value or increase the consumption value, we will usePassword_needs_rehash ()Function:
Only in this way, PHP'sPassword Hashing APIWe will know that we have re
:
$ Hash = password_hash ($ password, PASSWORD_BCRYPT, $ options );
// $ 2y $10 $ JDJ5JDEwJDhsTHV6SGVIQuprRHZnGQsUEtlk8Iem0okH6HPyCoo22
Now that the hash is created, you can use password_get_info () to view information about the hash value. Password_get_info () requires a parameter -- hash value -- and returns a contains algorithm (represented by an integer of the hash algorithm used), Algorithm Name (readable name of the hash algorithm used) and the associated array of options (which we use to
file. The file_size parameter is measured in megabytes (1,000,000 bytes, not 1,048,576 bytes ). -D provides the code that matches the information package in an assembly format that people can understand. -Dd provides the code that matches the information package in the format of the C program segment. -Ddd provides the matching information package code in decimal format. -D: print out all network interfaces in the system that can use tcpdump to capture packets. -E prints the header information
ports,--dports,--sports,--ports, specifying up to 15 ports at the same time IPRange: address range Matching (not written as network address);--src-range,-- Dst-rangestring: string matching;--string,--algo {KMP|BM},--hex-string "hex_string": hex_string for strings encoded in 16 binary format;Algorithms is the meaning of the algorithm, KMP|BM is the two encoding algorithms time: Based on the timing of matching;--datestart,--datestop,--timestart,--times
the largest, so next permutation 321 is completely inverted to the smallest 123.Algorithm Analysis:Reference: http://harrifeng.github.io/algo/leetcode/next-permutation.html
From back to front, find the first array[i]
If we exchange the 6 and 81 directly, it will certainly produce a permutation, but is not "the closest", how to find the "closest", from 1 to 8 behind this end looking for a bigger than 6, and 6 is the smallest difference
-type 8–j DROPNote: 6/m, where the m represents minutes, and the back of-limit-burst 10 means that every minute into 10 packets, do not forget the second rule, only two are input to function.9. Match the contents of the package insideSuppose an extranet attacker attacks an intranet IIS server by sending "./winnt/system32/cmd.exe?/c+dir", and we can try to exploit xt_ on the Linux gateway Firewall before the server vulnerability is fully repaired The matching function of the String.ko module temp
if the value is less than m constant plus 1, if equal to M, Position minus 1, that is, to move to the left one position, because the right side of the element will be adjusted after the left, so we have to check whether the rightmost element is less than m, if it is, then position adjust back to n-1, if not, then positon remains unchanged. Program code: #include using namespacestd;voidShowresult (intData[],intN) { for(intI=0; i) {cout" "; } coutEndl;}intGeneratenfromm (intMintN) { i
19 20 21 ... NFirst sieve the multiples of 2:2 3 5 7 9 11 13 15 17 19 21 ..... NThen sieve the multiples of 3:2 3 5 7 11 13 17 19 ..... NThen sift through the multiples of 5, then sift the 7 prime numbers, then sift the multiples of 11 .... So the last number left is prime, and this is the Eratosthenes screening method (Eratosthenes Sieve).The number of checks can also be reduced, in fact, as long as the check 6n+1 and 6n+5 can be, that is, directly skip the multiples of 2 and 3, so that the pr
. You need to create an associated array.
The code is as follows:
$ Options = ['cost' => 10,'Salt' => mcrypt_create_iv (22, MCRYPT_DEV_URANDOM)];
After the option is added to the password_hash () function, our hash value is changed, which is more secure.
The code is as follows:
$ Hash = password_hash ($ password, PASSWORD_BCRYPT, $ options );// $ 2y $10 $ JDJ5JDEwJDhsTHV6SGVIQuprRHZnGQsUEtlk8Iem0okH6HPyCoo22
Now that the hash is c
, which is more secure.
The code is as follows:
$ Hash = password_hash ($ password, PASSWORD_BCRYPT, $ options );// $ 2y $10 $ JDJ5JDEwJDhsTHV6SGVIQuprRHZnGQsUEtlk8Iem0okH6HPyCoo22
Now that the hash is created, you can use password_get_info () to view information about the hash value. Password_get_info () requires a parameter -- hash value -- and returns a contains algorithm (represented by an integer of the hash algorithm used), Algorithm Name (readable name of the hash algorithm used) and th
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