在PKCS#11中签名证书

Question

为了在OpenSSL中签名证书，我使用x509_sign()函数，向它提供一个请求（作为x509_req*)、一个签名密钥和一个摘要。

现在我有我的签名密钥存储在HSM中，所以我无法提取它来签名证书。不幸的是，PKCS#11没有提供x509_sign()的等价物。它只有c_sign()/C_SignUpdate()/C_SignFinal()系列函数，这些函数对原始数据进行操作，而不是对证书进行操作。

有人能帮助我使用示例C/C++代码如何使用PKCS#11签署一个用OpenSSL创建的证书吗？

Answer 1

下面的代码在HSM中为给定的X509*结构签名。为了清楚起见，省略了错误处理。

void signCertInHsm(X509* x509, unsigned long pkcs11SigningAlgo, CK_FUNCTION_LIST_PTR p11, CK_SESSION_HANDLE p11session, CK_OBJECT_HANDLE pkcs11PrivKeyHandle)
{
    x509->cert_info->enc.modified = 1;

    // set signature algorithm in the certificate
    if (x509->cert_info->signature)
    {
        const int signingAlgoNid = pkcs11SignatureAlgorithmToNid(pkcs11SigningAlgo);
        X509_ALGOR_set0(x509->cert_info->signature, OBJ_nid2obj(signingAlgoNid), V_ASN1_NULL, NULL);
    }
    if (x509->sig_alg)
    {
        const int signingAlgoNid = pkcs11SignatureAlgorithmToNid(pkcs11SigningAlgo);
        X509_ALGOR_set0(x509->sig_alg, OBJ_nid2obj(signingAlgoNid), V_ASN1_NULL, NULL);
    }

    // DER-encode certificate
    unsigned char *certDerBuf = NULL;
    const size_t certDerLen = ASN1_item_i2d((ASN1_VALUE*)x509->cert_info, &certDerBuf, ASN1_ITEM_rptr(X509_CINF));

    CK_MECHANISM mechanism = { pkcs11SigningAlgo, NULL_PTR, 0 };
    p11->C_SignInit(p11session, &mechanism, pkcs11PrivKeyHandle);

    // determine signature size
    CK_ULONG signatureSize = 0;
    p11->C_Sign(p11session, certDerBuf, certDerLen, NULL, &signatureSize);

    // sign
    if (x509->signature->data)
        OPENSSL_free(x509->signature->data);
    x509->signature->data = (unsigned char*)OPENSSL_malloc(signatureSize);
    x509->signature->length = signatureSize;
    p11->C_Sign(p11session, certDerBuf, certDerLen, x509->signature->data, &signatureSize);

    x509->signature->flags&= ~(ASN1_STRING_FLAG_BITS_LEFT|0x07);
    x509->signature->flags|=ASN1_STRING_FLAG_BITS_LEFT;

    OPENSSL_free(certDerBuf);
}

int pkcs11SignatureAlgorithmToNid(unsigned long algo)
{
    switch(algo)
    {
    case CKM_SHA1_RSA_PKCS: return NID_sha1WithRSAEncryption;
    case CKM_SHA256_RSA_PKCS: return NID_sha256WithRSAEncryption;
    //... add more mappings that your app supports
    default: throw std::invalid_argument("Not supported signature algorithm");
    }
}