oth
Registry Context
`oth` carries information about third and subsequent RSA primes in a multi-prime private key.
Technical Summary
In an RSA private JWK, `oth` is an array containing information for each prime factor after the first two.
When Used
RSA private keys constructed using three or more prime factors.
Normative Requirements
JWK consumer
RFC 7518 - Section 6.3.2.7
use the key.
Condition: when it does not support private keys with more than two primes and encounters a private key containing `oth`
MUST NOT use the key
JWK producer
RFC 7518 - Section 6.3.2.7
omit the `oth` parameter.
Condition: when only two primes have been used
this parameter MUST be omitted
RFC 7518 - Section 6.3.2.7
set the number of `oth` array elements to the number of primes used minus two.
Condition: when three or more primes have been used
the number of array elements MUST be the number of primes used minus two
RFC 7518 - Section 6.3.2.7
make each `oth` array element an object containing the defined `r`, `d`, and `t` members.
Condition: when `oth` is present
Each array element MUST be an object with the following members
Validation Guidance
Report an error if an RSA private JWK generated using exactly two primes contains `oth`.
Verify that the `oth` array length equals the number of primes used minus two.
Do not use a private key containing `oth` when the consumer lacks multi-prime RSA support.
Verify that every `oth` array element is an object containing `r`, `d`, and `t`.
Verify that each `r`, `d`, and `t` value is Base64urlUInt-encoded as specified by Sections 6.3.2.7.1 through 6.3.2.7.3.
Reference
Details
- Entry Id
oth- Parameter Name
oth- Parameter Description
Other Primes Info- Used With Kty Value
RSA- Parameter Information Class
Private- Change Controller
IESG- Reference
RFC7518 - Section 6.3.2.7