iPhone:如何将包含公钥位的SecKeyRef或NSData导出为PEM格式？

Question

我已经创建了一对密钥SecKeyGeneratePair.我现在想将公钥传递给服务器,但我不确定如何继续.

我有一个功能getPublicKeyBits(取自Apple的CryptoExercise),但我真的不知道如何处理原始NSData.这是功能:

- (NSData *)getPublicKeyBits {
    OSStatus sanityCheck = noErr;
    NSData* publicKeyBits = nil;
    NSData* publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:sizeof(publicKeyIdentifier)];
    CFDataRef cfresult = NULL;


    NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];

    // Set the public key query dictionary.
    [queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
    [queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
    [queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnData];

    // Get the key bits.
    sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)queryPublicKey, (CFTypeRef*)&cfresult); 


    if (sanityCheck != noErr)
    {
        publicKeyBits = nil;
    }
    else 
    {
        publicKeyBits = (__bridge_transfer NSData *)cfresult;
    }

    return publicKeyBits;
}

如何将这个原始字节数据转换成类似于PEM或加密库理解的其他格式？我应该base64编码吗？还有其他我需要做的事情吗？

如果它有帮助,我正在尝试将公钥与M2Crypto可用于Python 的库一起使用.

Answer 1

我想你可能想看看http://www.openssl.org/docs/crypto/pem.html# ：

int PEM_write_PrivateKey(FILE *fp, EVP_PKEY *x, const EVP_CIPHER *enc,
                                    unsigned char *kstr, int klen,
                                    pem_password_cb *cb, void *u);