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What are some tips and examples for using the Windows C/C++ Crypto API?

asked 2021-07-08 11:00:00 +0000

huitzilopochtli gravatar image

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answered 2021-11-15 20:00:00 +0000

lakamha gravatar image

Here are some tips and examples for using the Windows C/C++ Crypto API:

  1. Familiarize yourself with the Crypto API documentation: Before diving into coding, make sure you have a good understanding of how the Crypto API works and what functions are available to you. Microsoft provides a comprehensive documentation on the Crypto API on their website.

  2. Use cryptographic hashes: One of the key features of the Crypto API is the ability to compute cryptographic hashes. You can use these hashes to verify the integrity of data or authentication.

  3. Use asymmetric encryption: Another important feature of the Crypto API is asymmetric encryption, which allows you to encrypt data using a public key and decrypt it using a private key. This is useful for securing communication between systems or encrypting data for storage.

  4. Protect sensitive data: The Crypto API also provides functions for generating and using digital certificates, which can be used to protect sensitive data or secure communications.

  5. Examples: Here are some code snippets for using the Crypto API:

Compute a hash:

HCRYPTPROV hProv = 0;
HCRYPTHASH hHash = 0;
BYTE pbData[] = "Data to hash";
DWORD dwDataLen = sizeof(pbData);

CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0);
CryptCreateHash(hProv, CALG_SHA1, 0, 0, &hHash);
CryptHashData(hHash, pbData, dwDataLen, 0);
BYTE pbHash[SHA1_DIGEST_SIZE];
DWORD dwHashLen = SHA1_DIGEST_SIZE;
CryptGetHashParam(hHash, HP_HASHVAL, pbHash, &dwHashLen, 0);
CryptDestroyHash(hHash);
CryptReleaseContext(hProv, 0);

Encrypt using a public key:

HCRYPTPROV hProv = 0;
HCRYPTKEY hPublicKey = 0;
BYTE pbData[] = "Data to encrypt";
DWORD dwDataLen = sizeof(pbData);

CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0);
CryptImportPublicKeyInfo(hProv, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, /*public key info struct*/, &hPublicKey);
DWORD dwBlockSize = 0;
CryptEncrypt(hPublicKey, 0, TRUE, 0, NULL, &dwBlockSize, 0);
BYTE pbEncrypted[dwBlockSize];
CryptEncrypt(hPublicKey, 0, TRUE, 0, pbData, &dwDataLen, dwBlockSize);
CryptDestroyKey(hPublicKey);
CryptReleaseContext(hProv, 0);

Generate a digital certificate:

HCRYPTPROV hProv = 0;
BOOL bResult = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0);
CRYPT_KEY_PROV_INFO keyProvInfo = {0};
keyProvInfo.pwszContainerName = /*container name*/;
keyProvInfo.pwszProvName = /*provider name*/;
keyProvInfo.dwProvType = PROV_RSA_FULL;
keyProvInfo.dwFlags = CRYPT_MACHINE_KEYSET;
CERT_NAME_BLOB subjectName = {0};
subjectName.pbData = /*subject name*/;
subjectName.cbData = /*length of subject name*/;
PCCERT_CONTEXT pCertContext = CertCreateSelfSignCertificate(hProv, &subjectName, 0, &keyProvInfo, 0, 0, 0, 0); 
CertAddCertificateContextToStore(/*certificate store*/, pCertContext, CERT_STORE_ADD_REPLACE_EXISTING, NULL);
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Asked: 2021-07-08 11:00:00 +0000

Seen: 14 times

Last updated: Nov 15 '21