code: function decode(pem) {
    if (Buffer.isBuffer(pem)) {
      pem = pem.toString('ascii')
    }
  
    const lines = pem.trim().split('\n')
  
    if (lines.length < 3) {
      throw new Error('Invalid PEM data.')
    }
  
    const match = header.exec(lines[0])
  
    if (match === null) {
      throw new Error('Invalid label.')
    }
  
    const label = match[1]
    let i = 1
  
    for (; i < lines.length; ++i) {
      if (lines[i].startsWith(after)) {
        break
      }
    }
  
    const footer = new RegExp(`^${after} ${label}${endline}\r?\n?$`)
  
    if (footer.exec(lines[i]) === null) {
      throw new Error('Invalid end of file.')
    }
  
    const body = lines.slice(1, i).join('\n').replace(/\r?\n/g, '')
    return Buffer.from(body, 'base64')
  }
docs: Convert PEM formatted data to raw buffer.
  @param {Buffer|String} pem
  @returns {Buffer}