AES Encryption Tool

Free online AES encryption decryption tool supporting multiple encryption modes (CBC, ECB, CFB, OFB, CTR) and padding methods. Provides key generation, hex and Base64 format conversion for secure data transmission.

Encryption Settings

Key and IV Settings

Encrypt/Decrypt Operations

AES Encryption Knowledge

Background of AES Algorithm

The AES algorithm officially replaced DES as the new generation encryption standard in 2001. This transformation originated from a global algorithm solicitation activity initiated by the National Institute of Standards and Technology (NIST). After rigorous screening, the Rijndael algorithm ultimately prevailed and was established as Federal Information Processing Standard FIPS 197, marking the entry of encryption technology into a new stage of development.

Common Application Scenarios

  • Government/military communication encryption
  • Financial transaction data protection
  • Enterprise sensitive document storage
  • SSL/TLS network transmission encryption

Operation Modes

AES Encryption Mode Diagram

Mode Comparison Table

Mode Initialization Vector Parallelism Error Propagation
CBC Required None Block-level
CTR Counter Initial Value Supported No propagation

Padding Modes

Mode Standard Document Padding Scheme Use Case
PKCS#7 RFC 5652 Pad n bytes with value n General data
ZeroPadding Industry Practice Pad with 0x00 bytes Binary data
ISO/IEC 7816-4 ISO Standard First byte 0x80 followed by 0x00 Smart card apps

Key Length

  • Standard Lengths: 128/192/256 bits
  • Selection Criteria:
    • 128 bits: Regular commercial applications
    • 256 bits: Government/military grade data
  • Compatibility: Complies with NIST SP 800-131A

Security Considerations

  1. IV Management Standards:
    • CBC mode uses cryptographically secure random numbers
    • CTR mode counter never repeats
  2. Key Derivation:
    • Recommended PBKDF2-HMAC-SHA256
    • Iteration count ≥10,000 times
  3. Authenticated Encryption:
    • Avoid using ECB mode

References