@sphereon/ssi-sdk-ext.kms-musap-rn/src/MusapKeyManagerSystem.ts

Sphereon SSI-SDK react-native plugin for management of keys with musap.

import { PEMToBinary } from '@sphereon/ssi-sdk-ext.x509-utils'
import { IKey, ManagedKeyInfo, MinimalImportableKey, TKeyType } from '@veramo/core'
import {
  ExternalSscdSettings,
  IMusapClient,
  isSignatureAlgorithmType,
  JWSAlgorithm,
  KeyAlgorithm,
  KeyAlgorithmType,
  KeyAttribute,
  KeyGenReq,
  MusapClient,
  MusapKey,
  signatureAlgorithmFromKeyAlgorithm,
  SignatureAlgorithmType,
  SignatureAttribute,
  SignatureFormat,
  SignatureReq,
  SscdType,
} from '@sphereon/musap-react-native'
import { AbstractKeyManagementSystem } from '@veramo/key-manager'
import { TextDecoder } from 'text-encoding'
import { Loggers } from '@sphereon/ssi-types'
import { KeyMetadata } from './index'
import {
  asn1DerToRawPublicKey,
  calculateJwkThumbprintForKey,
  hexStringFromUint8Array,
  isAsn1Der,
  isRawCompressedPublicKey,
  toRawCompressedHexPublicKey,
} from '@sphereon/ssi-sdk-ext.key-utils'
import * as u8a from 'uint8arrays'

export const logger = Loggers.DEFAULT.get('sphereon:musap-rn-kms')

export class MusapKeyManagementSystem extends AbstractKeyManagementSystem {
  private musapClient: IMusapClient
  private readonly sscdType: SscdType
  private readonly sscdId: string
  private readonly defaultKeyAttributes: Record<string, string> | undefined
  private readonly defaultSignAttributes: Record<string, string> | undefined

  constructor(sscdType?: SscdType, sscdId?: string, opts?: {
    externalSscdSettings?: ExternalSscdSettings,
    defaultKeyAttributes?: Record<string, string>,
    defaultSignAttributes?: Record<string, string>
  }) {
    super()
    try {
      this.musapClient = MusapClient
      this.sscdType = sscdType ? sscdType : 'TEE'
      this.sscdId = sscdId ?? this.sscdType
      this.defaultKeyAttributes = opts?.defaultKeyAttributes
      this.defaultSignAttributes = opts?.defaultSignAttributes

      const enabledSscds = this.musapClient.listEnabledSscds()
      if (!enabledSscds.some(value => value.sscdId == sscdId)) {
        this.musapClient.enableSscd(this.sscdType, this.sscdId, opts?.externalSscdSettings)
      }
    } catch (e) {
      console.error('enableSscd', e)
      throw Error('enableSscd failed')
    }
  }

  async listKeys(): Promise<ManagedKeyInfo[]> {
    const keysJson: MusapKey[] = (this.musapClient.listKeys()) as MusapKey[]
    return keysJson.map((key) => this.asMusapKeyInfo(key))
  }

  async createKey(args: { type: TKeyType; meta?: KeyMetadata }): Promise<ManagedKeyInfo> {
    const { type, meta } = args
    if (meta === undefined || !('keyAlias' in meta)) {
      return Promise.reject(Error('a unique keyAlias field is required for MUSAP'))
    }

    if (this.sscdType == 'EXTERNAL') {
      const existingKeys: MusapKey[] = (this.musapClient.listKeys()) as MusapKey[]
      const extKey = existingKeys.find(musapKey => musapKey.sscdType as string === 'External Signature') // FIXME returning does not match SscdType enum
      if (extKey) {
        extKey.algorithm = 'eccp256r1' // FIXME MUSAP announces key as rsa2k, but it's actually EC
        return this.asMusapKeyInfo(extKey)
      }
      return Promise.reject(Error(`No external key was bound yet for sscd ${this.sscdId}`))
    }

    const keyGenReq = {
      keyAlgorithm: this.mapKeyTypeToAlgorithmType(type),
      keyUsage: 'keyUsage' in meta ? (meta.keyUsage as string) : 'sign',
      keyAlias: meta.keyAlias as string,
      attributes: this.recordToKeyAttributes({ ...this.defaultKeyAttributes, ...('attributes' in meta ? meta.attributes : {}) }),
      role: 'role' in meta ? (meta.role as string) : 'administrator',
    } satisfies KeyGenReq

    try {
      const generatedKeyUri = await this.musapClient.generateKey(this.sscdType, keyGenReq)
      if (generatedKeyUri) {
        logger.debug('Generated key:', generatedKeyUri)
        const key = this.musapClient.getKeyByUri(generatedKeyUri)
        return this.asMusapKeyInfo(key)
      } else {
        return Promise.reject(new Error('Failed to generate key. No key URI'))
      }
    } catch (error) {
      logger.error('An error occurred:', error)
      throw error
    }
  }

  private mapKeyTypeToAlgorithmType = (type: TKeyType): KeyAlgorithmType => {
    switch (type) {
      case 'Secp256k1':
        return 'ECCP256K1'
      case 'Secp256r1':
        return 'ECCP256R1'
      case 'RSA':
        return 'RSA2K'
      default:
        throw new Error(`Key type ${type} is not supported by MUSAP`)
    }
  }

  private mapAlgorithmTypeToKeyType = (type: KeyAlgorithm): TKeyType => {
    switch (type) {
      case 'eccp256k1':
        return 'Secp256k1'
      case 'eccp256r1':
        return 'Secp256r1'
      case 'ecc_ed25519':
        return 'Ed25519'
      case 'rsa2k':
      case 'rsa4k':
        return 'RSA'
      default:
        throw new Error(`Key type ${type} is not supported.`)
    }
  }

  async deleteKey({ kid }: { kid: string }): Promise<boolean> {
      try {
        const key: MusapKey = this.musapClient.getKeyById(kid) as MusapKey
        if (key.sscdType as string === 'External Signature') {
          return true // FIXME we can't remove a eSim key for now because this would mean onboarding again
        }
        void this.musapClient.removeKey(kid)
      return true
    } catch (error) {
      console.warn('Failed to delete key:', error)
      return false
    }
  }

  private determineAlgorithm(providedAlgorithm: string | undefined, keyAlgorithm: KeyAlgorithm): SignatureAlgorithmType {
    if (providedAlgorithm === undefined) {
      return signatureAlgorithmFromKeyAlgorithm(keyAlgorithm)
    }

    if (isSignatureAlgorithmType(providedAlgorithm)) {
      return providedAlgorithm
    }

    // Veramo translates TKeyType to JWSAlgorithm
    return signatureAlgorithmFromKeyAlgorithm(providedAlgorithm as JWSAlgorithm)
  }

  async sign(args: {
    keyRef: Pick<IKey, 'kid'>;
    algorithm?: string;
    data: Uint8Array;
    [x: string]: any
  }): Promise<string> {
    if (!args.keyRef) {
      throw new Error('key_not_found: No key ref provided')
    }

    const data = new TextDecoder().decode(args.data as Uint8Array)

    const key: MusapKey = this.musapClient.getKeyById(args.keyRef.kid) as MusapKey
    if (key.sscdType as string === 'External Signature') {
      key.algorithm = 'eccp256r1' // FIXME MUSAP announces key as rsa2k, but it's actually EC
    }
    const signatureReq: SignatureReq = {
      keyUri: key.keyUri,
      data,
      algorithm: this.determineAlgorithm(args.algorithm, key.algorithm),
      displayText: args.displayText,
      transId: args.transId,
      format: (args.format as SignatureFormat) ?? 'RAW',
      attributes: this.recordToSignatureAttributes({ ...this.defaultSignAttributes, ...args.attributes }),
    }
    return this.musapClient.sign(signatureReq)
  }

  async importKey(args: Omit<MinimalImportableKey, 'kms'> & { privateKeyPEM?: string }): Promise<ManagedKeyInfo> {
    throw new Error('importKey is not implemented for MusapKeyManagementSystem.')
  }

  private decodeMusapPublicKey = (args: { publicKey: { pem: string }, keyType: TKeyType }): string => {
    const { publicKey, keyType } = args

    // First try the normal PEM decoding path
    const pemBinary = PEMToBinary(publicKey.pem)

    // Check if we got a string that looks like base64 (might be double encoded)
    // Convert Uint8Array to string safely
    const pemString = u8a.toString(pemBinary, 'utf8')
    const isDoubleEncoded = pemBinary.length > 0 &&
      typeof pemString === 'string' &&
      pemString.startsWith('MF')

    if (isDoubleEncoded) {
      // Handle double-encoded case
      const actualDerBytes = u8a.fromString(pemString, 'base64')

      // For double-encoded case, we know the key data starts after the header
      const keyDataStart = 24
      const keyData = actualDerBytes.slice(keyDataStart)

      // Convert to public key hex
      let publicKeyHex = u8a.toString(keyData, 'hex')

      // If it's not compressed yet and doesn't start with 0x04 (uncompressed point marker), add it
      if (publicKeyHex.length <= 128 && !publicKeyHex.startsWith('04')) {
        publicKeyHex = '04' + publicKeyHex
      }

      // Ensure we have full 65 bytes for uncompressed keys
      while (publicKeyHex.startsWith('04') && publicKeyHex.length < 130) {
        publicKeyHex = publicKeyHex + '0'
      }

      // Now convert to compressed format if needed
      if (publicKeyHex.startsWith('04') && publicKeyHex.length === 130) {
        const xCoord = u8a.fromString(publicKeyHex.slice(2, 66), 'hex')
        const yCoord = u8a.fromString(publicKeyHex.slice(66, 130), 'hex')
        const prefix = new Uint8Array([yCoord[31] % 2 === 0 ? 0x02 : 0x03])
        const compressedKey = new Uint8Array(33) // 1 byte prefix + 32 bytes x coordinate
        compressedKey.set(prefix, 0)
        compressedKey.set(xCoord, 1)
        return u8a.toString(compressedKey, 'hex')
      }

      return publicKeyHex
    }

    // Not double encoded, proceed with normal path
    const publicKeyBinary = isAsn1Der(pemBinary) ? asn1DerToRawPublicKey(pemBinary, keyType) : pemBinary
    return isRawCompressedPublicKey(publicKeyBinary)
      ? hexStringFromUint8Array(publicKeyBinary)
      : toRawCompressedHexPublicKey(publicKeyBinary, keyType)
  }
  

  private asMusapKeyInfo(args: MusapKey): ManagedKeyInfo {
    const { keyId, publicKey, ...metadata }: KeyMetadata = { ...args }
    const keyType = this.mapAlgorithmTypeToKeyType(args.algorithm)

    const publicKeyHex = this.decodeMusapPublicKey({
      publicKey: publicKey,
      keyType: keyType
    })

    const keyInfo: Partial<ManagedKeyInfo> = {
      kid: keyId,
      type: keyType,
      publicKeyHex,
      meta: metadata,
    }

    const jwkThumbprint = calculateJwkThumbprintForKey({ key: keyInfo as ManagedKeyInfo })
    keyInfo.meta = { ...keyInfo.meta, jwkThumbprint }
    return keyInfo as ManagedKeyInfo
  }

  sharedSecret(args: { myKeyRef: Pick<IKey, 'kid'>; theirKey: Pick<IKey, 'publicKeyHex' | 'type'> }): Promise<string> {
    throw new Error('Not supported.')
  }

  private recordToKeyAttributes(record?: Record<string, string>): KeyAttribute[] {
    if (!record) {
      return []
    }
    return Object.entries(record).map(([key, value]) => ({
      name: key,
      value,
    }))
  }

  private recordToSignatureAttributes(record?: Record<string, string>): SignatureAttribute[] {
    if (!record) {
      return []
    }
    return Object.entries(record).map(([key, value]) => ({
      name: key,
      value,
    }))
  }
}