在答案裡面有提到,即使在不考慮 ASIC 的情況下,光是用 GPU 算就可以可以降到 ~5.4 GPU years 了:
Remarkably, we can see that in only 5 years, we're down from an attack costing ~110 GPU years to an attack costing ~8 GPU-years in 2020 (thanks to theoretical improvements & newer GPUs) to just ~5.4 GPU years nowadays (thanks to newer, faster GPUs).
In a more realistic way, it would take less than a day to do it on a super-computer such as the one owned by the US Department of Energy's Oak Ridge National Laboratory (ORNL) named "Summit".
In particular, you can specify the use of any one of four widely used checksum algorithms (SHA-1, SHA-256, CRC-32, and CRC-32C) when you upload each of your objects to S3.
丟進 array 是 OK 的,但問題在於他需要判斷 entry 是否重複,卻沒有用 hash 或是 tree 的結構,而這邊大約有 63k 筆資料,用 array 實做就產生了 O(n^2) 的演算法:
But before it’s stored? It checks the entire array, one by one, comparing the hash of the item to see if it’s in the list or not. With ~63k entries that’s (n^2+n)/2 = (63000^2+63000)/2 = 1984531500 checks if my math is right. Most of them useless. You have unique hashes why not use a hash map.
if it’s called again within the string’s range, return cached value
而第二個問題他直接把檢查是否有重複的跳過,因為資料本身不重複:
And as for the hash-array problem, it’s more straightforward - just skip the duplicate checks entirely and insert the items directly since we know the values are unique.
I found this while making a collection of what C implementation does what at https://news.ycombinator.com/item?id=26298300.
There are two basic implementation strategies. The BSD (FreeBSD and OpenBSD and more than likely NetBSD too), Microsoft, GNU, and MUSL C libraries use one, and suffer from this; whereas the OpenWatcom, P.J. Plauger, Tru64 Unix, and my standard C libraries use another, and do not.
The 2002 report in the comp.lang.c Usenet newsgroup (listed in that discussion) is the earliest that I've found so far.
For comparison, Instagram sends ~200 byte base64 thumbnails in its API responses. It's a low-res JPEG with a fixed header to save a bit more space. This is also used to blur sensitive images. You can get even better results with webp.
In 2008, researchers used a chosen-prefix collision attack against MD5 using this scenario, to produce a rogue certificate authority certificate. They created two versions of a TLS public key certificate, one of which appeared legitimate and was submitted for signing by the RapidSSL certificate authority. The second version, which had the same MD5 hash, contained flags which signal web browsers to accept it as a legitimate authority for issuing arbitrary other certificates.[14]
TLS server certificates and issuing CAs using RSA keys must use key sizes greater than or equal to 2048 bits. Certificates using RSA key sizes smaller than 2048 bits are no longer trusted for TLS.
TLS server certificates and issuing CAs must use a hash algorithm from the SHA-2 family in the signature algorithm. SHA-1 signed certificates are no longer trusted for TLS.
TLS server certificates must present the DNS name of the server in the Subject Alternative Name extension of the certificate. DNS names in the CommonName of a certificate are no longer trusted.
bash /usr/share/elasticsearch/plugins/opendistro_security/tools/hash.sh
WARNING: JAVA_HOME not set, will use /usr/bin/java
[Password:]
$2y$12$QchkpgY8y/.0TL7wruWq4egBDrlpIaURiBYKoZD50G/twdylgwuhG