swift - 如何从 SecCertificate 中提取或比较 kSecPropertyKeyValue

Question

需要解析和比较证书值，但其中一些以 Data 形式返回，而不会解析为字符串。大多数属性以数字或字符串形式返回，但 kSecPropertyKeyValue 是 CFData 数组。需要此功能来显示与钥匙串(keychain)访问类似的证书信息。

import Foundation
import Security

let query: [CFString: Any] = [
    kSecClass: kSecClassCertificate,
    kSecReturnAttributes: kCFBooleanTrue,
    kSecReturnRef: kCFBooleanTrue,
    kSecReturnData: kCFBooleanTrue,
    kSecMatchLimit: kSecMatchLimitAll
]

var result: AnyObject?
SecItemCopyMatching(query as CFDictionary, &result)
let certs: [SecCertificate] = (result as? [[CFString: Any]])?.map({ $0[kSecValueRef] as! SecCertificate }) ?? []

for cert in certs {
    if let values: [CFString:Any] = (SecCertificateCopyValues(cert, [kSecOIDExtendedKeyUsage] as CFArray, nil) as? [CFString:Any])?[kSecOIDExtendedKeyUsage] as? [CFString:Any] {

        // Expect to find `kSecOIDExtendedUseCodeSigning` value or something else
        // meaningful. How do I do that?

        print(
            "type:", values[kSecPropertyKeyType]!,
            "||| data values:", values[kSecPropertyKeyValue] as! [Data],
            "||| cString:", (values[kSecPropertyKeyValue] as! [CFData]).map({ String(cString: CFDataGetBytePtr($0)) }),
            "||| string:", (values[kSecPropertyKeyValue] as! [Data]).map({ String(data: $0, encoding: .utf8) })
        )
    }
}

粘贴到 Playground ，打印:

type: array ||| data values: [8 bytes] ||| cString: ["+\u{06}\u{01}\u{05}\u{05}\u{07}\u{03}\u{04}"] ||| string: [Optional("+\u{06}\u{01}\u{05}\u{05}\u{07}\u{03}\u{04}")]
type: array ||| data values: [9 bytes] ||| cString: ["*�H��cd\u{04}\t"] ||| string: [nil]

有些看起来像 unicode 转义，有些看起来像无效字符串。任何帮助表示赞赏。

Answer 1

显然 OID 值没有可读的字符串表示形式，而是常量，可以在 google/der-ascii 中找到。 .

例如，上面的输出 +\u{06}\u{01}\u{05}\u{05}\u{07}\u{03}\u{04} 匹配 0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x03, 0x04，即 email protection (+ 是 0x2b，以字节为单位)。