Quick Reference Guide to Identifying Common Cryptographic Hash Formats

Cryptographic hashes and encodings each carry distinct structural signatures that security professionals can use to identify them without decryption. Bcrypt hashes, for example, are exactly 60 characters long, begin with a versioned prefix such as $2a$ or $2y$, and embed both a cost factor and a 22-character salt directly in the string. Standard fast hashes like MD5, SHA-1, and SHA-256 are identified purely by their hexadecimal character set and fixed lengths of 32, 40, and 64 characters respectively. Slower, salted formats such as SHA-512 Crypt and Argon2 include explicit prefix markers like $6$ or $argon2id$ and store algorithm parameters within the hash string itself. A key distinction for security practitioners is that encoded data such as Base64 or ROT13 is reversible, whereas cryptographic hashes are one-way functions designed to resist brute-force attacks through techniques like key stretching.