adler32

How reliable is the adler32 checksum?

由 六月ゝ 毕业季﹏ 提交于 2020-01-01 04:12:07
问题 I wonder how reliable the adler32 checksum is, compared to e.g. md5 checksums? It was told on wikipedia that adler32 is "much less reliable" than md5, so I wonder how much, and in which way? More specifically, I'm wondering if it is reliable enough as a consistency check for long-time archiving of (tar) files of size 20GB+? 回答1: For details on the error-checking capabilities of the Adler-32 checksum, see for example Revisiting Fletcher and Adler Checksums. Maxino, 2006. This paper contains an

A palette base PNG with IDAT that has BTYPE=00 for no compression, now with Adler32 code

由 浪子不回头ぞ 提交于 2019-12-08 04:37:54
问题 I am working on some code that builds simple palette based PNG files without libpng. The output file, at this stage only has IHDR, PLTE, IDAT(x3) and IEND chunks. The only thing which is possibly a bit different in that the pixel index values in the IDAT chunk are not compressed, that is the various zlib / block header bytes are as follows. CMF = 0x78. FLG = 0x9C (have also a few other values here but always with bit 5 clear). Block header byte = 0x01 (BFINAL = 1, BTYPE = 00). From what I can

Differences in calculation of adler32 rolling checksum - python

由 跟風遠走 提交于 2019-12-08 04:05:12
问题 Need a clarification while looking at calculating a running checksum. Assume I have data like this. data = 'helloworld' Assuming a blocksize of 5, I need to calculate running checksum. >>> zlib.adler32('hello') 103547413 >>> zlib.adler32('ellow') 105316900 According to Python documentation (python version 2.7.2) zlib.adler32(data[, value]) "Computes a Adler-32 checksum of data. (An Adler-32 checksum is almost as reliable as a CRC32 but can be computed much more quickly.) If value is present,

Adler32 Repeating Very Quickly

由 和自甴很熟 提交于 2019-12-05 01:00:34
问题 I'm using the adler32 checksum algorithm to generate a number from a database id. So, when I insert a row into the database, I take the identity of that row and use it to create the checksum. The problem that I'm running into is that I just generated a repeat checksum after only 207 inserts into the database. This is much much faster than I expected. Here is my code: String dbIdStr = Long.toString(dbId); byte[] bytes = dbIdStr.getBytes(); Checksum checksum = new Adler32(); checksum.update

How reliable is the adler32 checksum?

由 半世苍凉 提交于 2019-12-03 10:02:37
I wonder how reliable the adler32 checksum is, compared to e.g. md5 checksums? It was told on wikipedia that adler32 is "much less reliable" than md5, so I wonder how much, and in which way? More specifically, I'm wondering if it is reliable enough as a consistency check for long-time archiving of (tar) files of size 20GB+? For details on the error-checking capabilities of the Adler-32 checksum, see for example Revisiting Fletcher and Adler Checksums. Maxino, 2006. This paper contains an analysis on the Hamming distance provided by these two checksums, and provides an indication of the
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