输出SecKeyCopyExternalRepresentation

Question

我试图将iPhone中的公钥传递给其他方，但是我无法使用iOS的输出。在

let parameters: [String: Any] = [
    kSecAttrKeySizeInBits as String: 384,
    kSecAttrKeyType as String: kSecAttrKeyTypeEC,
    kSecPrivateKeyAttrs as String: [
        kSecAttrIsPermanent as String: false
    ]
]

var error: Unmanaged<CFError>?
let privateKey = SecKeyCreateRandomKey(parameters as CFDictionary, &error)
let publicKey = SecKeyCopyPublicKey(privateKey!)

let pub = SecKeyCopyExternalRepresentation(publicKey!, &error)
let pubData = pub as Data?
print(pubData!.base64EncodedString())

输出示例：

BJSCZtBatd2BYEHtyLB0qTZNlphKf3ZTGI6Nke3dSxIDpyP9FWMZbG0zcdIXWENyndskfxV0No/yz369ngL2EHZYw6ggNysOnZ5IQSPOLFFl44m1aAk0o0NdaRXTVAz4jQ==

在python中（我的第二方在那里），我有以下内容：

^{pr2}$

我得到的错误是ValueError: Could not deserialize key data.

那么，文档中描述的SecKeyCopyExternalRepresentation的输出到底是什么：

The method returns data in the PCKS #1 format for an RSA key. For an elliptic curve public key, the format follows the ANSI X9.63 standard using a byte string of 04 || X || Y. For an elliptic curve private key, the output is formatted as the public key concatenated with the big endian encoding of the secret scalar, or 04 || X || Y || K. All of these representations use constant size integers, including leading zeros as needed.

如何描述X6.93格式？如何将它转换成可以在python代码中使用的东西呢？在

另外，我已经尝试向xcode输出添加诸如-----BEGIN PUBLIC KEY-----这样的头。在

Answer 1

我还没有找到这个问题的答案，因为我仍然不知道苹果到底提供了什么输出，但是，我想出了一个在this key import export manager中找到的解决方案。在

let parameters: [String: Any] = [
    kSecAttrKeySizeInBits as String: 384,
    kSecAttrKeyType as String: kSecAttrKeyTypeEC,
    kSecPrivateKeyAttrs as String: [
        kSecAttrIsPermanent as String: false
    ]
]

var pubKey: SecKey?
var priKey: SecKey?
var error: Unmanaged<CFError>?
let keyPair = SecKeyGeneratePair(parameters as CFDictionary, &pubKey, &priKey)

let publicKeyData = SecKeyCopyExternalRepresentation(pubKey!, &error)
// Code from the library
let ieManager = CryptoExportImportManager()
if let exportPEM = ieManager.exportPublicKeyToPEM(publicKeyData as Data!, keyType: kSecAttrKeyTypeEC as String, keySize: 384) {
    print(exportPEM)
} else {
    print("Error exporting to PEM")
}

输出示例：

Exporting EC raw key: 97 bytes -BEGIN PUBLIC KEY - MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEFpCnTrJFQq0mZBvy+vzl9noKLZ4/s1cf I6hygug6s8dvBreMhabAcAbbhSa1losjCxV450nq92W9ZymonYasaAuhshDWjmvx 2qTXHEpVEVb9GawqX6XqpWtIBf+meHKS -END PUBLIC KEY -

python中的实现using cryptography

^{pr2}$

输出如下： <cryptography.hazmat.backends.openssl.ec._EllipticCurvePublicKey object at 0x7fb4f6f50e10>

请注意，您必须自己在python中添加新行，才能使这一切正常工作。在

Answer 2

BJSCZtBatd2BYEHtyLB0qTZNlphKf3ZTGI6Nke3dSxIDpyP9FWMZbG0zcdIXWENyndskfxV0No/yz369ngL2EHZYw6ggNysOnZ5IQSPOLFFl44m1aAk0o0NdaRXTVAz4jQ==

键的格式不正确。

它似乎是一个EC密钥。我怀疑它是公开的，详细说明是04 || X || Y，但我可能错了。你知道什么领域的钥匙结束了吗？该字段告诉您X和Y中有多少字节。在

$ cat key.dat
BJSCZtBatd2BYEHtyLB0qTZNlphKf3ZTGI6Nke3dSxIDpyP9FWMZbG0zcdIXWENyndskfxV0No/yz369ngL2EHZYw6ggNysOnZ5IQSPOLFFl44m1aAk0o0NdaRXTVAz4jQ==

$ base64 -d key.dat | hexdump -C
00000000  04 94 82 66 d0 5a b5 dd  81 60 41 ed c8 b0 74 a9  |...f.Z...`A...t.|
00000010  36 4d 96 98 4a 7f 76 53  18 8e 8d 91 ed dd 4b 12  |6M..J.vS......K.|
00000020  03 a7 23 fd 15 63 19 6c  6d 33 71 d2 17 58 43 72  |..#..c.lm3q..XCr|
00000030  9d db 24 7f 15 74 36 8f  f2 cf 7e bd 9e 02 f6 10  |..$..t6...~.....|
00000040  76 58 c3 a8 20 37 2b 0e  9d 9e 48 41 23 ce 2c 51  |vX.. 7+...HA#.,Q|
00000050  65 e3 89 b5 68 09 34 a3  43 5d 69 15 d3 54 0c f8  |e...h.4.C]i..T..|
00000060  8d                                                |.|
00000061