e
Registry Context
The `e` parameter contains an RSA public key's exponent and is encoded as a Base64urlUInt. It must be present in an RSA public key JWK. For exponent 65537, the encoded value is `AQAB`.
Technical Summary
RFC 7518 defines `e` as the Base64urlUInt-encoded exponent value for an RSA public key. Section 6.3.1 requires the RSA public-key members, including `e`, to be present. Section 6.3.1.2 requires exponent 65537 to use the octet sequence [1, 0, 1] before base64url encoding, resulting in `AQAB`.
When Used
When representing an RSA public key as a JWK.
Normative Requirements
A JWK producer representing an RSA public key
RFC 7518 - Section 6.3.1
include the `e` member.
Condition: when representing an RSA public key
The following members MUST be present for RSA public keys.
An implementation representing RSA exponent 65537
RFC 7518 - Section 6.3.1.2
use the three-octet sequence [1, 0, 1] as the input to base64url encoding.
Condition: when representing the value 65537 in the `e` parameter
the octet sequence to be base64url-encoded MUST consist of the three octets [1, 0, 1]
Validation Guidance
Reject an RSA public key JWK that omits `e`.
For exponent 65537, verify that the Base64urlUInt encoding is `AQAB`, derived from the octet sequence [1, 0, 1].
Reference
Details
- Entry Id
e- Parameter Name
e- Parameter Description
Exponent- Used With Kty Value
RSA- Parameter Information Class
Public- Change Controller
IESG- Reference
RFC7518 - Section 6.3.1.2