Question

如何使用RSA密钥在iOS上签名和验证某些数据（最好使用系统自己的libcommonCrypto）？

Answer 1

由于几乎没有关于在StackOverflow和Apple文档上发现的签名和验证的任何知识，我不得不在iOS头文件中手动浏览并找到SecKeyRawSign和SecKeyRawVerify。以下代码行似乎有效。

签署NSData（使用带有RSA的SHA256）：

NSData* PKCSSignBytesSHA256withRSA(NSData* plainData, SecKeyRef privateKey)
{
    size_t signedHashBytesSize = SecKeyGetBlockSize(privateKey);
    uint8_t* signedHashBytes = malloc(signedHashBytesSize);
    memset(signedHashBytes, 0x0, signedHashBytesSize);

    size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;
    uint8_t* hashBytes = malloc(hashBytesSize);
    if (!CC_SHA256([plainData bytes], (CC_LONG)[plainData length], hashBytes)) {
        return nil;
    }

    SecKeyRawSign(privateKey,
                  kSecPaddingPKCS1SHA256,
                  hashBytes,
                  hashBytesSize,
                  signedHashBytes,
                  &signedHashBytesSize);

    NSData* signedHash = [NSData dataWithBytes:signedHashBytes
                                        length:(NSUInteger)signedHashBytesSize];

    if (hashBytes)
        free(hashBytes);
    if (signedHashBytes)
        free(signedHashBytes);

    return signedHash;
}

验证（使用带RSA的SHA256）：

BOOL PKCSVerifyBytesSHA256withRSA(NSData* plainData, NSData* signature, SecKeyRef publicKey)
{
    size_t signedHashBytesSize = SecKeyGetBlockSize(publicKey);
    const void* signedHashBytes = [signature bytes];

    size_t hashBytesSize = CC_SHA256_DIGEST_LENGTH;
    uint8_t* hashBytes = malloc(hashBytesSize);
    if (!CC_SHA256([plainData bytes], (CC_LONG)[plainData length], hashBytes)) {
        return nil;
    }

    OSStatus status = SecKeyRawVerify(publicKey,
                                      kSecPaddingPKCS1SHA256,
                                      hashBytes,
                                      hashBytesSize,
                                      signedHashBytes,
                                      signedHashBytesSize);

    return status == errSecSuccess;
}

替代方案（OpenSSL）：

有一个非常好的替代品可以直接使用OpenSSL而不是libCommonCrypto。 MIHCrypto是一个精心设计的OpenSSL Objective-C包装器库，它使得加密技术变得非常容易。请参阅下面的示例。

生成密钥非常简单：

MIHAESKeyFactory *factory = [[MIHAESKeyFactory alloc] init];
id<MIHSymmetricKey> aesKey = [factory generateKey];

或从文件加载密钥：

NSData *privateKeyData = [[NSFileManager defaultManager] contentsAtPath:"mykey.pem"];
MIHRSAPrivateKey *privateKey = [[MIHRSAPrivateKey alloc] initWithData:privateKeyData];

现在签名：

NSError *signingError = nil;
NSData *message = // load something to sign from somewhere
NSData *signature = [privateKey signWithSHA256:message error:&signingError]

有关更多示例，请浏览MIHCrypto页面。

Answer 2

其实简单多了，不需要手动创建hash

func validateRSASignature(signedData: Data, signature: Data, publicKeyData: Data) -> Bool {

    // Create a SecKey instance from the public key data.
    let publicKey: SecKey! = SecKeyCreateWithData(publicKeyData as NSData, [
        kSecAttrKeyType: kSecAttrKeyTypeRSA,
        kSecAttrKeyClass: kSecAttrKeyClassPublic
    ] as NSDictionary, nil)

    // Verify the RSA signature.
    return SecKeyVerifySignature(publicKey,
                                 .rsaSignatureMessagePKCS1v15SHA512,
                                 signedData as NSData,
                                 signature as NSData,
                                 nil)
}

从 iOS 10 开始这应该是可能的。如果您的关键数据和其他输入发生变化，您可能需要扩展错误处理。

使用RSA在iOS上签名和验证

2 个答案: