From 55b3088e47690f2a8a152ceb44bba786810abb28 Mon Sep 17 00:00:00 2001
From: bnMikheili <39998190+bnMikheili@users.noreply.github.com>
Date: Sun, 14 Jun 2020 11:49:39 +0400
Subject: [PATCH] Hash adler32 (#2111)

* implement hash

* fix indentation
---
 hashes/adler32.py | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 hashes/adler32.py

diff --git a/hashes/adler32.py b/hashes/adler32.py
new file mode 100644
index 000000000..8b82fff47
--- /dev/null
+++ b/hashes/adler32.py
@@ -0,0 +1,27 @@
+"""
+    Adler-32 is a checksum algorithm which was invented by Mark Adler in 1995.
+    Compared to a cyclic redundancy check of the same length, it trades reliability for speed (preferring the latter).
+    Adler-32 is more reliable than Fletcher-16, and slightly less reliable than Fletcher-32.[2]
+
+    source: https://en.wikipedia.org/wiki/Adler-32
+"""
+
+
+def adler32(plain_text: str) -> str:
+    """
+    Function implements adler-32 hash.
+    Itterates and evaluates new value for each character
+
+    >>> adler32('Algorithms')
+    363791387
+
+    >>> adler32('go adler em all')
+    708642122
+    """
+    MOD_ADLER = 65521
+    a = 1
+    b = 0
+    for plain_chr in plain_text:
+        a = (a + ord(plain_chr)) % MOD_ADLER
+        b = (b + a) % MOD_ADLER
+    return (b << 16) | a