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ECB

Electronic Codebook mode encrypts each block independently using the underlying block cipher. This is the simplest mode but reveals patterns in plaintext data, making it unsuitable for most cryptographic applications. Educational implementation for learning cipher modes.

Properties

Property	Value
Category	Cipher Modes
Sub-category	Block Cipher Mode
Security status	❌ Broken
Complexity	Beginner
Inventor	US National Bureau of Standards
Year	1977
Origin	🇺🇸 United States
Source	algorithms/modes/ecb.js

Capabilities

Flag	Value
RequiresIV	No

Security

Status: ❌ Broken

Known vulnerabilities

Issue	Description	Mitigation
Pattern Leakage	Identical plaintext blocks produce identical ciphertext blocks, revealing patterns	—
Block Replay	Individual blocks can be extracted and replayed in different positions	—
Known Plaintext	If attacker knows one block plaintext/ciphertext pair, identical blocks elsewhere are compromised	—

Documentation

• NIST SP 800-38A
• FIPS 81 (Historical)

References

• Cryptography Engineering — Chapter on block cipher modes
• Applied Cryptography — Bruce Schneier - Chapter 9

Test vectors

2 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — AES-128 ECB test vector

Field	Value
key	2b7e151628aed2a6abf7158809cf4f3c
cipher	AES
input	6bc1bee22e409f96e93d7e117393172a
expected	3ad77bb40d7a3660a89ecaf32466ef97

Vector 2 — AES-128 ECB second block

Field	Value
key	2b7e151628aed2a6abf7158809cf4f3c
cipher	AES
input	ae2d8a571e03ac9c9eb76fac45af8e51
expected	f5d3d58503b9699de785895a96fdbaaf

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