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y

IESG

Registry Context

`y` contains the Y coordinate of an elliptic curve point, encoded using base64url. Its decoded octet string must have the full coordinate size for the curve identified by `crv`.

Technical Summary

The `y` parameter is the base64url encoding of the octet string representation of an elliptic curve point's Y coordinate, as defined by SEC1 Section 2.3.5. RFC 7518 requires that octet string to have the full coordinate size of the curve specified by `crv`.

When Used

When representing or validating the Y coordinate of an EC JWK public key.

Normative Requirements

The octet string representation of the `y` coordinate

MUST
1
  1. RFC 7518 - Section 6.2.1.3

    have the full size of a coordinate for the curve specified by `crv`.

    The length of this octet string MUST be the full size of a coordinate for the curve specified in the "crv" parameter.

Validation Guidance

error

Decode `y` from base64url and verify that the resulting octet string has the full coordinate size for the curve specified by `crv`.

Reference

Details

Entry Id
y
Parameter Name
y
Parameter Description
Y Coordinate
Used With Kty Value
EC
Parameter Information Class
Public
Change Controller
IESG
Reference
RFC7518 - Section 6.2.1.3