Symmetric Encryption & Block Ciphers
Encrypt and decrypt text with a shared secret key. Modern authenticated ciphers and legacy block modes, running entirely in your browser.
AES Encryption
Encrypt text with AES-256 in GCM, CBC, or CTR mode
XOR · BRUTEFORCEXOR Cipher
Bitwise XOR with a repeating key, plus single-byte bruteforce
CHACHA20 · AEADChaCha20-Poly1305
Modern authenticated stream cipher, password-based
SALSA20 · STREAMSalsa20
The stream cipher that ChaCha20 was built from
RC4 · STREAMRC4 Stream Cipher
The classic (broken) stream cipher, for education and interop
Triple DES & DES
Legacy DES and 3DES block cipher tool
Blowfish & Twofish
Blowfish and Twofish encryption suite
Camellia
Camellia block cipher tool
CAST-128 & CAST-256
CAST family cipher utility
Choosing the right symmetric encryption tool
Symmetric ciphers use one shared secret key to both encrypt and decrypt, and they do the heavy lifting of almost all real-world encryption — HTTPS traffic, disk encryption, encrypted backups and messaging all end up in AES or ChaCha20. For new work, pick an authenticated (AEAD) cipher: AES-256-GCM or ChaCha20-Poly1305. Both detect tampering on decryption, which older modes like AES-CBC and plain stream ciphers cannot.
AES-GCM is the default when the hardware has AES acceleration (virtually every modern laptop, phone and server); ChaCha20-Poly1305 is the equal alternative that stays fast and constant-time in pure software. Salsa20, RC4 and repeating-key XOR are here for interoperability, CTF challenges and learning — RC4 in particular is broken and should never protect real data. Whatever the cipher, the key matters most: these tools derive it from your password with PBKDF2 and a random salt, so use a long passphrase.
Encoding vs Encryption vs Hashing: The Difference, With Examples
Encoding, encryption and hashing all turn data into gibberish, but only one keeps secrets. Learn the difference with real Base64, AES and SHA-256 examples and when to use each.
6 MIN READSYMMETRIC · AESAES-GCM vs CBC vs CTR vs ECB: Which AES Mode Should You Use?
AES is only as safe as its mode. Compare ECB, CBC, CTR and GCM — how each works, how each fails, and why AES-GCM (or ChaCha20-Poly1305) is the right default in 2026.
7 MIN READPOST-QUANTUM · STANDARDSPost-Quantum Cryptography in 2026: What ML-KEM and ML-DSA Mean for You
A practical guide to post-quantum cryptography: what quantum computers break (and don't), the NIST standards ML-KEM, ML-DSA and SLH-DSA, where PQC is already deployed, and what to do now.
6 MIN READCLASSICAL · CRYPTANALYSISHow to Break a Vigenère Cipher Without the Key: A Worked Example
Step-by-step cryptanalysis of a real Vigenère ciphertext: find the key length with Kasiski examination and the index of coincidence, then recover each key letter with chi-squared frequency analysis.
8 MIN READ