我在苹果的Swift中开发iOS应用。因为这是一个安全应用程序,所以我需要为后端生成此内容。
我对安全证书等方面并不熟悉,已经搜索了一天,但没有任何结果。
如何使用Swift生成2048位RSA公钥的base64 url编码X.509格式?
非常感谢任何帮助。
最近我创建了一个名为Heimdall的Swift公私钥对处理库,它允许您轻松导出公钥的X.509格式的Base64字符串。
为了遵守SO规则,我也会在这个答案中包含实现(以便自我解释)。
public func X509PublicKey() -> NSString? {
// Fetch the key, so that key = NSData of the public key
let result = NSMutableData()
let encodingLength: Int = {
if key.length + 1 < 128 {
return 1
} else {
return ((key.length + 1) / 256) + 2
}
}()
let OID: [CUnsignedChar] = [0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00]
var builder: [CUnsignedChar] = []
// ASN.1 SEQUENCE
builder.append(0x30)
// Overall size, made of OID + bitstring encoding + actual key
let size = OID.count + 2 + encodingLength + key.length
let encodedSize = encodeLength(size)
builder.extend(encodedSize)
result.appendBytes(builder, length: builder.count)
result.appendBytes(OID, length: OID.count)
builder.removeAll(keepCapacity: false)
builder.append(0x03)
builder.extend(encodeLength(key.length + 1))
builder.append(0x00)
result.appendBytes(builder, length: builder.count)
// Actual key bytes
result.appendData(key)
// Convert to Base64 and make safe for URLs
var string = result.base64EncodedStringWithOptions(.allZeros)
string = string.stringByReplacingOccurrencesOfString("/", withString: "_")
string = string.stringByReplacingOccurrencesOfString("+", withString: "-")
return string
}
public func encodeLength(length: Int) -> [CUnsignedChar] {
if length < 128 {
return [CUnsignedChar(length)];
}
var i = (length / 256) + 1
var len = length
var result: [CUnsignedChar] = [CUnsignedChar(i + 0x80)]
for (var j = 0; j < i; j++) {
result.insert(CUnsignedChar(len & 0xFF), atIndex: 1)
len = len >> 8
}
return result
}
// Create dictionary to specify attributes for the key we're
// searching for. Swift will automatically bridge native values
// to to right types for the SecItemCopyMatching() call.
var queryAttrs = [NSString:AnyObject]()
queryAttrs[kSecClass] = kSecClassKey
queryAttrs[kSecAttrApplicationTag] = publicKeyTag
queryAttrs[kSecAttrKeyType] = kSecAttrKeyTypeRSA
queryAttrs[kSecReturnData] = true
var publicKeyBits = Unmanaged<AnyObject>?()
SecItemCopyMatching(queryAttrs, &publicKeyBits)
// Work around a compiler bug with Unmanaged<AnyObject> types
// the following two lines should simply be
// let publicKeyData : NSData = publicKeyRef!.takeRetainedValue() as NSData
let opaqueBits = publicKeyBits?.toOpaque()
let publicKeyData = Unmanaged<NSData>.fromOpaque(opaqueBits).takeUnretainedValue()
let publicKeyBase64 = publicKeyData.base64EncodedData(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
如果需要生成密钥对并将其存储在密钥链中,请使用以下代码:
// Create dictionaries to specify key attributes. Swift will
// automatically bridge native values to to right types for the
// SecKeyGeneratePair() call.
var pairAttrs = [NSString:AnyObject]()
var privateAttrs = [NSString:AnyObject]()
var publicAttrs = [NSString:AnyObject]()
privateAttrs[kSecAttrIsPermanent] = true
privateAttrs[kSecAttrApplicationTag] = privateKeyTag
publicAttrs[kSecAttrIsPermanent] = true
publicAttrs[kSecAttrApplicationTag] = publicKeyTag
pairAttrs[kSecAttrKeyType] = kSecAttrKeyTypeRSA
pairAttrs[kSecAttrKeySizeInBits] = 2048
pairAttrs[(kSecPrivateKeyAttrs.takeUnretainedValue() as! String)] = privateAttrs
pairAttrs[(kSecPublicKeyAttrs.takeUnretainedValue() as! String)] = publicAttrs
var publicKeyPtr = Unmanaged<SecKey>?()
var privateKeyPtr = Unmanaged<SecKey>?()
let status = SecKeyGeneratePair(pairAttrs, &publicKeyPtr, &privateKeyPtr)
注意:publicKeyTag
和privateKeyTag
是用于在密钥库中标识密钥的字符串。苹果建议使用反向DNS表示法(com.company.key.xxx),但只要它们是唯一的,就应该没问题。
类似的问题和答案: 在iPhone上生成密钥对并将其作为NSString打印到日志中
尽管那里的答案是用Objective-C编写的,但Apple参考文献显示,这些函数(特别是最重要的SecKeyGeneratePair
)也可以直接从Swift调用(只要您可以从所有这些UnsafeMutablePointers等类型转换)。