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import cbor from 'cbor';
import type { SigningSchemeHash } from 'node-rsa';
/**
* Takes COSE-encoded public key and converts it to PKCS key
*
* @param cosePublicKey COSE-encoded public key
* @return RAW PKCS encoded public key
*/
export default function convertCOSEtoPKCS(cosePublicKey: Buffer): Buffer {
/*
+------+-------+-------+---------+----------------------------------+
| name | key | label | type | description |
| | type | | | |
+------+-------+-------+---------+----------------------------------+
| crv | 2 | -1 | int / | EC Curve identifier - Taken from |
| | | | tstr | the COSE Curves registry |
| | | | | |
| x | 2 | -2 | bstr | X Coordinate |
| | | | | |
| y | 2 | -3 | bstr / | Y Coordinate |
| | | | bool | |
| | | | | |
| d | 2 | -4 | bstr | Private key |
+------+-------+-------+---------+----------------------------------+
*/
const struct: COSEPublicKey = cbor.decodeFirstSync(cosePublicKey);
const tag = Buffer.from([0x04]);
const x = struct.get(COSEKEYS.x);
const y = struct.get(COSEKEYS.y);
if (!x) {
throw new Error('COSE public key was missing x');
}
if (y) {
return Buffer.concat([tag, x as Buffer, y as Buffer]);
}
return Buffer.concat([tag, x as Buffer]);
}
export type COSEPublicKey = Map<COSEAlgorithmIdentifier, number | Buffer>;
export enum COSEKEYS {
kty = 1,
alg = 3,
crv = -1,
x = -2,
y = -3,
n = -1,
e = -2,
}
export enum COSEKTY {
OKP = 1,
EC2 = 2,
RSA = 3,
}
export const COSERSASCHEME: { [key: string]: SigningSchemeHash } = {
'-3': 'pss-sha256',
'-39': 'pss-sha512',
'-38': 'pss-sha384',
'-65535': 'pkcs1-sha1',
'-257': 'pkcs1-sha256',
'-258': 'pkcs1-sha384',
'-259': 'pkcs1-sha512',
};
// See https://w3c.github.io/webauthn/#sctn-alg-identifier
export const COSECRV: { [key: number]: string } = {
// alg: -7
1: 'p256',
// alg: -35
2: 'p384',
// alg: -36
3: 'p521',
// alg: -8
6: 'ed25519',
};
export const COSEALGHASH: { [key: string]: string } = {
'-257': 'sha256',
'-258': 'sha384',
'-259': 'sha512',
'-65535': 'sha1',
'-39': 'sha512',
'-38': 'sha384',
'-37': 'sha256',
'-7': 'sha256',
'-8': 'sha512',
'-36': 'sha512',
};
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