加密后如何解密才能取回原始字符串

Question

我是iOS和Swift的新手。我想用公钥加密一个字符串。公钥是这样的：

"-----BEGIN PUBLIC KEY-----
Some String
-----END PUBLIC KEY-----"

我搜索了它，得到并实现了以下代码：

static func encrypt(string: String, publicKey: String?) -> String? {
guard let publicKey = publicKey else { return nil }
let keyString = publicKey.replacingOccurrences(of: "-----BEGIN PUBLIC KEY-----n", with: "").replacingOccurrences(of: "n-----END PUBLIC KEY-----", with: "")
guard let data = Data(base64Encoded: keyString) else { return nil }
var attributes: CFDictionary {
return [kSecAttrKeyType         : kSecAttrKeyTypeRSA,
kSecAttrKeyClass        : kSecAttrKeyClassPublic,
kSecAttrKeySizeInBits   : 2048,
kSecReturnPersistentRef : kCFBooleanTrue] as CFDictionary
}
var error: Unmanaged<CFError>? = nil
guard let secKey = SecKeyCreateWithData(data as CFData, attributes, &error) else {
print(error.debugDescription)
return nil
}
return encrypt(string: string, publicKey: secKey)
}
static func encrypt(string: String, publicKey: SecKey) -> String? {
let buffer = [UInt8](string.utf8)
var keySize   = SecKeyGetBlockSize(publicKey)
var keyBuffer = [UInt8](repeating: 0, count: keySize)
// Encrypto  should less than key length
guard SecKeyEncrypt(publicKey, SecPadding.PKCS1, buffer, buffer.count, &keyBuffer, &keySize) == errSecSuccess else { return nil }
return Data(bytes: keyBuffer, count: keySize).base64EncodedString()
}

再次感谢StackOverflow。现在的问题是，我无法解密此函数返回的加密字符串。对于编码，我想要2048位的大小。对于安卓来说，这就是加密的方式：

public String encryptKey() throws NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException, InvalidKeyException, CertificateException {

publicKey = getPublicKey();

Cipher oaepFromAlgo = Cipher.getInstance("RSA/NONE/OAEPWITHSHA-256ANDMGF1PADDING");
oaepFromAlgo.init(Cipher.ENCRYPT_MODE, publicKey );
//byte[] ct = oaepFromAlgo.doFinal(secretKey.toString().getBytes(StandardCharsets.UTF_8));
byte[] ct = oaepFromAlgo.doFinal(secretKey.getEncoded());
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
return Base64.getEncoder().encodeToString(ct);
}
else{
return android.util.Base64.encodeToString(ct,android.util.Base64.DEFAULT);
}
}

private PublicKey getPublicKey() throws CertificateException {
CertificateFactory f = CertificateFactory.getInstance("X.509");
X509Certificate certificate = (X509Certificate)f.generateCertificate(getTrustedCertificatesInputStream());
return certificate.getPublicKey();
}

如果有人能指导我如何解密，如果我的加密过程与安卓类似，这将非常有帮助。

Answer 1

衷心感谢所有试图解决这个问题的人。我自己做到了。我没有将公钥作为字符串，而是通过将crt文件转换为der 来提取公钥作为secKey