Security & Encoding

WWI German cipher: 6×6 Polybius substitution + columnar transposition.

Compute the Adler-32 checksum used by zlib / PNG.

Encrypt or decrypt text with AES-256-GCM and a passphrase.

Encrypt or decrypt with AES-256 in CBC or (educational) ECB mode using a passphrase.

Substitution cipher y = (ax + b) mod 26 with a coprime to 26.

Generate an MD5 entry for an Apache .htdigest file.

Generate Argon2id password hashes with configurable parameters.

Encode and decode standard RFC 4648 Base32 with padding.

Encode and decode Bitcoin-style Base58.

Encode and decode Base62 (URL-safe alphanumeric).

Encode bytes to Base85 (Ascii85) and decode them back.

Compact basE91 binary-to-text encoding (~14% denser than Base64).

Hash a password with Bcrypt or verify a hash.

Reciprocal Vigenère variant: encrypt and decrypt are identical.

Polybius-based fractionating cipher (5×5 grid).

Generate or verify a BIP-39 seed phrase.

Compute BLAKE2b cryptographic hashes (RFC 7693).

Encrypt by writing text into a square and reading down the columns.

Encrypt or decrypt text with ChaCha20-Poly1305 AEAD and a passphrase.

Estimate the cipher type from letter statistics and list all 25 Caesar shifts.

Encrypt text with a keyword-driven columnar transposition.

Compute CRC-16-CCITT and CRC-32 (IEEE 802.3) checksums.

Build a Content Security Policy from checkboxes or lint an existing CSP for foot-guns.

Generate memorable Diceware passphrases.

Walk through a Diffie–Hellman exchange and confirm both sides derive the same secret.

Generate an Ed25519 key pair — raw hex, PEM and OpenSSH formats.

Simulate a 3-rotor Enigma (I-II-III, reflector B) — symmetric encrypt/decrypt.

Two-keyword digraph substitution over four 5×5 squares.

Hash a password with SHA-1 and show the 5-char prefix for the HIBP range API.

Matrix-based classical cipher with a 2×2 key matrix mod 26.

Derive keys from high-entropy material using HKDF.

Compute keyed HMAC signatures (SHA-1, SHA-256, SHA-384, SHA-512).

Build a signed-token preview from JSON header and payload data.

Compute the MD5 hash of any text.

Chain base64, gzip, url and hex transforms in a single pass.

Compute the NTLM (MD4 over UTF-16LE) hash of a password.

Decode an OpenID Connect ID token and pretty-print its claims.

Generate or apply a one-time pad — XOR with a random key.

Build an otpauth:// URI from issuer, account and Base32 secret.

Generate strong, cryptographically-random passwords.

Check a password against a configurable length/character-class policy.

Estimate password entropy and strength in real time.

Derive a key from a password using PBKDF2.

Convert between PEM (base64) and DER (binary/hex) for X.509 and keys.

Work with armored PGP-style text payloads in-browser.

Group a hex PGP fingerprint into the standard 4-/20-char layout.

Classic 5×5 digraph substitution cipher.

Substitute each letter with its row + column digits on a 5×5 grid.

Find the registrable domain for any hostname using a built-in suffix list.

Decode QR code images back to text.

Encode and decode MIME Quoted-Printable.

Encode or decode ROT13 and simple Caesar-shift text.

Reciprocal cipher over the printable ASCII range (33–126).

Generate a fresh RSA public + private key pair (PEM).

Decode and inspect a SAML 2.0 Response — raw XML, base64, or base64+deflated.

Base64-decode, inflate and pretty-print a SAML request or response.

Ancient transposition cipher — wrap text around a rod of N rows.

Generate a self-signed X.509 RSA certificate (PEM) for dev / staging.

Compute SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text.

Compute SHA3-256, SHA3-384 and SHA3-512 hashes.

Split a secret into N shares with a K-of-N threshold.

Generate RSA or Ed25519 SSH key material for testing.

Inspect any OpenSSH or PEM key — type, bit length, MD5 + SHA-256 fingerprints.

Parse known_hosts entries: host pattern, key type and SHA-256 fingerprint.

Paste a PEM-encoded SSL certificate to inspect its fields.

Generate a sha256/384/512-prefixed SRI hash for a file or text.

Prisoner-of-war 5×5 tap-pair encoder (K shares C's cell).

Generate a Time-based One-Time Password (RFC 6238) — SHA-1, SHA-256 or SHA-512.

Fractionating cipher over a 3×3×3 cube (26 letters + '+').

Convert UUID values to byte-array notation.

Estimate the key length of a Vigenère ciphertext via Index of Coincidence.

Generate a Curve25519 private/public/preshared key triplet for a WireGuard tunnel.

Apply a repeating-key XOR to text or bytes.