🐍 Serpent-256

AES Finalist — 32 Rounds of Conservative Security

Encrypt

Passphrase

Plaintext

Output

Argon2id Parameters

Time cost: 3 iterations
Memory cost: 65,536 KiB (64 MiB)
Parallelism: 1
Output: 32 bytes (256-bit key)
Salt: 16 bytes (random per operation)

Decrypt

Passphrase

Encrypted Payload (JSON)

Decrypted Output

Security Margin Visualization

Performance Comparison

Note: Both ciphers execute every round of their full specification — Serpent-256-CTR runs all 32 rounds per block, AES-256-GCM runs all 14. AES-256-GCM benefits from hardware acceleration (AES-NI) via the Web Crypto API. Serpent-256-CTR runs in WebAssembly without hardware acceleration. This comparison reflects real-world browser throughput, not algorithmic speed.

Data size

Iterations

About Serpent

The Designers

Eli Biham — Technion, Israel Institute of Technology, Israel. Co-inventor of differential cryptanalysis (with Adi Shamir). Pioneer of block cipher analysis.
Ross Anderson — University of Cambridge, UK. Security engineering researcher. Contributed the overall architecture and design philosophy.
Lars Knudsen — Technical University of Denmark (DTU). Expert in integral and impossible differential cryptanalysis. Key contributor to the S-box design.

Israeli Cryptographic Lineage

Eli Biham studied under Adi Shamir (the "S" in RSA) at the Weizmann Institute. Together they developed differential cryptanalysis — the technique that broke DES and reshaped how every modern block cipher is designed. Biham brought this deep understanding of attack mechanisms to Serpent's design, building a cipher specifically resistant to the techniques he himself had pioneered.

AES Competition Outcome

In the AES competition (1997–2000), Serpent placed second to Rijndael. Rijndael received 86 votes to Serpent's 59. NIST's selection criteria weighted performance alongside security. Rijndael was faster with fewer rounds (10/12/14 vs 32), while Serpent prioritized a conservative security margin — using twice as many rounds as needed to block all known shortcut attacks at the time.