Cryptography for Hackers

No. Base64 is an encoding: a public, keyless mapping into a safe alphabet. Anyone can decode it with base64 -d, so a Base64-encoded password or API secret should be treated as plaintext.

Encryption is reversible with the right key and protects confidentiality. Hashing is one-way, uses no key and produces a fixed-length digest, so it is used for integrity checks and password verification rather than for hiding data you need back.

Start with the length of the hex string: 32 characters suggests MD5, 40 suggests SHA-1, 64 suggests SHA-256 and 128 suggests SHA-512. Length is a strong hint, not proof, so confirm with context such as the application or file format.

Attackers guess candidate passwords, hash each guess and compare it with the stored digest. Fast, unsalted hashes such as plain MD5 make this practical for weak passwords, which is why password storage should use Argon2id, scrypt or bcrypt with unique salts.

openssl enc writes the ASCII header Salted__ followed by an 8-byte salt before the ciphertext. Salted__ in Base64 begins with U2FsdGVkX1, so the prefix identifies password-based OpenSSL encryption, where the password is usually the weak point rather than AES.

A salt does not need to be secret. Its job is to make identical passwords produce different stored values and to make precomputed tables useless, so an attacker must attack every entry separately. Formats such as $6$salt$hash or OpenSSL's Salted__ header therefore store it openly.