Security Glossary

JSON Web Encryption (JWE)

A standard for encrypting JWT content, providing confidentiality in addition to the integrity protection offered by JWS signatures.

JSON Web Encryption (JWE) is a standard (RFC 7516) for encrypting content to be represented as a JSON-based data structure. While JWS provides integrity and authentication, JWE adds confidentiality by encrypting the payload.

Structure

JWE tokens have five Base64URL-encoded parts:

header.encrypted_key.iv.ciphertext.tag

eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe...
48V1_ALb6US04U3b.
5eym8TW_c8SuK0ltJ3rpYI...
XFBoMYUZodetZdvTiFvSkQ

Components

  • Header: Encryption algorithm (alg) and content encryption (enc)
  • Encrypted Key: Content encryption key encrypted with recipient's key
  • IV: Initialization vector for content encryption
  • Ciphertext: Encrypted payload
  • Authentication Tag: Integrity protection

Common Algorithms

// Key encryption (alg)
RSA-OAEP, RSA1_5, A256KW, dir

// Content encryption (enc)
A256GCM, A128CBC-HS256

When to Use

  • Tokens contain sensitive data (PII, secrets)
  • Payload should not be readable by client
  • Defense in depth alongside HTTPS

Security Considerations

  • Choose strong encryption algorithms
  • Validate algorithm headers to prevent downgrade
  • Properly manage encryption keys
  • Consider using nested JWE+JWS for signed encryption

PentesterLab Exercises

See Also