如果不了解CryptoAPI，这应该是非常困难的。

主要障碍是：

使用CryptStringToBinaryA和CryptDecodeObjectEx解码X509 DSA公钥

转换DSA签名格式

OpenSSL的DSA_sign以ASN.1 DER格式生成DSA签名

CryptoAPI的CryptVerifySignature需要P1363格式的DSA签名

以下是我最终解决问题的粗略示例：

const char* pubKey = "MIIBtjCCASsGByqGSM44BAEwggEeAoGBANW/k8nYREKtRMvIShnJTSAwxF33haU4"

.....

"/FEGAibbOp31rjq9UfaJ2t06eN0t0B+DP1hjz/MfpGtPOxHqF3dQnDRa3ot1FSTP";

bool verify(const unsigned char* msgData, unsigned int msgLength, const unsigned char* signature, unsigned int signatureLength)

{

HCRYPTPROV hCryptProv;

if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_DSS, CRYPT_VERIFYCONTEXT))

{

return false;

}

bool result = false;

unsigned char derPubKey[2048];

DWORD derPubKeyLen = 2048;

CERT_PUBLIC_KEY_INFO *publicKeyInfo = NULL;

DWORD publicKeyInfoLen = 0;

if ( CryptStringToBinaryA( pubKey, strlen(pubKey), CRYPT_STRING_BASE64, derPubKey, &derPubKeyLen, NULL, NULL ) &&

CryptDecodeObjectEx( X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO, derPubKey, derPubKeyLen,

CRYPT_ENCODE_ALLOC_FLAG, NULL, &publicKeyInfo, &publicKeyInfoLen ) )

{

HCRYPTKEY hPubKey;

if (CryptImportPublicKeyInfo(hCryptProv, X509_ASN_ENCODING, publicKeyInfo, &hPubKey))

{

HCRYPTHASH hHash;

if (CryptCreateHash(hCryptProv, CALG_SHA1, 0, 0, &hHash))

{

CryptHashData(hHash, msgData, msgLength, 0);

BYTE* dsaSignature = NULL;

DWORD dsaSignatureLen = 0;

if (CryptDecodeObjectEx( X509_ASN_ENCODING, X509_DSS_SIGNATURE, signature, signatureLength,

CRYPT_ENCODE_ALLOC_FLAG, NULL, &dsaSignature, &dsaSignatureLen ) )

{

if (CryptVerifySignature(hHash, dsaSignature, dsaSignatureLen, hPubKey, NULL, 0))

{

result = true;

}

LocalFree(dsaSignature);

}

CryptDestroyHash(hHash);

}

CryptDestroyKey(hPubKey);

}

LocalFree(publicKeyInfo);

}

CryptReleaseContext(hCryptProv, 0);

return result;

}