Understanding how to identify common hash algorithms is a fundamental skill for anyone involved in security, reverse engineering, or data analysis. While complex analysis might sometimes be needed, often a simple examination of the hash string itself is sufficient. The primary method for quick identification relies on two key factors: the length of the hash output and the character set used. Different algorithms produce hashes of fixed lengths, regardless of the input size. For instance, a MD5 hash will always be 32 hexadecimal characters long. A SHA-1 hash is consistently 40 hexadecimal characters. Moving to the SHA-2 family, SHA-256 outputs a 64-character hexadecimal string, while SHA-512 results in a much longer 128-character hexadecimal string. Another frequently encountered hash type, NTLM, is identifiable by its 32-character hexadecimal representation, distinct from MD5 often by context or the specific tool producing it. By simply counting the characters and noting if they are standard hexadecimal (0-9, a-f) or perhaps a different encoding like Base64 (less common for raw hashes but seen in specific formats), you can quickly narrow down the possibilities. This simple check using known output lengths provides a highly effective first step in determining which cryptographic hash function was likely used. Mastering this basic identification technique saves significant time and effort when encountering unknown hash values.
Source: https://www.linuxlinks.com/hashes-simple-hash-algorithm-identification/
