RSA-SHA1 signing with a PKCS#12 private key

RSASHA1.swift

//
// RSASHA1.swift
//
// Copyright (c) 2015 Neil Cowburn. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

import Security

public typealias RSASigningResult = (signedData: NSData?, error: NSError?)

public func rsa_sha1(data plainData: NSData, #privateKey: SecKey!) -> RSASigningResult {
    var digest = NSMutableData(length: Int(CC_SHA1_DIGEST_LENGTH))!

    // Hash the data
    CC_SHA1(plainData.bytes, CC_LONG(plainData.length), UnsafeMutablePointer<UInt8>(digest.mutableBytes))

    // Then sign it
    var signedData = NSMutableData(length: SecKeyGetBlockSize(privateKey))!
    var signedDataLength = signedData.length

    let err: OSStatus = SecKeyRawSign(privateKey,
        SecPadding(kSecPaddingPKCS1SHA1),
        UnsafePointer<UInt8>(digest.bytes),
        digest.length,
        UnsafeMutablePointer<UInt8>(signedData.mutableBytes),
        &signedDataLength)

    if err == errSecSuccess {
        return (signedData: signedData, error: nil)
    }

    return (signedData: nil, error: NSError(domain: NSOSStatusErrorDomain, code: Int(err), userInfo: nil))

}

public func PKCS12ReadKey(path keyFilePath: String, #password: String?) -> SecKey? {
    let p12KeyFileContent = NSData(contentsOfFile: keyFilePath, options: .DataReadingMappedAlways, error: nil)

    if (p12KeyFileContent == nil) {
        NSLog("Cannot read PKCS12 file from \(keyFilePath)")
        return nil
    }

    let options = [String(kSecImportExportPassphrase.takeUnretainedValue()):password ?? ""]
    var citems: Unmanaged<CFArray>? = nil
    let resultPKCS12Import = withUnsafeMutablePointer(&citems) { citemsPtr in
        SecPKCS12Import(p12KeyFileContent, options, citemsPtr)
    }
    if (resultPKCS12Import != errSecSuccess) {
        return nil
    }

    let items = citems!.takeRetainedValue() as NSArray
    let myIdentityAndTrust = items.objectAtIndex(0) as! NSDictionary
    let identityKey = String(kSecImportItemIdentity.takeUnretainedValue())
    let identity = myIdentityAndTrust[identityKey] as! SecIdentity

    let trustKey = String(kSecImportItemTrust.takeUnretainedValue())
    let trust = myIdentityAndTrust[trustKey] as! SecTrust

    // MARK - Private Key

    var privateKey: Unmanaged<SecKey>? = nil
    let resultCopyPrivateKey = withUnsafeMutablePointer(&privateKey) {
        privateKeyPtr in
        SecIdentityCopyPrivateKey(identity, privateKeyPtr)
    }
    if (resultCopyPrivateKey != errSecSuccess) {
        NSLog("SecIdentityCopyPrivateKey fail")
        return nil
    }

    return privateKey!.takeRetainedValue()
}