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(Unicode C) RSA Encrypt and Decrypt Credit Card NumbersUnicode C sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.)
#include <C_CkRsaW.h> #include <C_CkPrivateKeyW.h> void ChilkatSample(void) { HCkRsaW rsa; HCkPrivateKeyW key; BOOL success; const wchar_t *keyXml; const wchar_t *ccNumber; BOOL usePrivateKey; const wchar_t *encryptedStr; HCkRsaW rsaDecryptor; const wchar_t *decryptedStr; // This example assumes the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. rsa = CkRsaW_Create(); key = CkPrivateKeyW_Create(); // Load an RSA private key from a file: success = CkPrivateKeyW_LoadAnyFormatFile(key,L"rsaPrivateKey.key",L""); if (success != TRUE) { wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(key)); CkRsaW_Dispose(rsa); CkPrivateKeyW_Dispose(key); return; } // Get the key as XML: keyXml = CkPrivateKeyW_getXml(key); // We'll encrypt with the public key and decrypt with the private // key. (It's also possible to do the reverse.) // Note: An RSA private key is composed of different parts internally: modulus, exponent, P, Q, etc. // An RSA public-key is a sub-set of the private key. // Therefore, when you have a private key, you really have // both public and private keys. success = CkRsaW_ImportPublicKey(rsa,keyXml); if (success != TRUE) { wprintf(L"%s\n",CkRsaW_lastErrorText(rsa)); CkRsaW_Dispose(rsa); CkPrivateKeyW_Dispose(key); return; } // Encrypt a VISA credit card number: // 1234-5678-0000-9999 ccNumber = L"1234567800009999"; usePrivateKey = FALSE; CkRsaW_putEncodingMode(rsa,L"base64"); encryptedStr = CkRsaW_encryptStringENC(rsa,ccNumber,usePrivateKey); wprintf(L"Encrypted:\n"); wprintf(L"%s\n",encryptedStr); // Now decrypt: rsaDecryptor = CkRsaW_Create(); CkRsaW_putEncodingMode(rsaDecryptor,L"base64"); success = CkRsaW_ImportPrivateKey(rsaDecryptor,keyXml); usePrivateKey = TRUE; decryptedStr = CkRsaW_decryptStringENC(rsaDecryptor,encryptedStr,usePrivateKey); wprintf(L"Decrypted:\n"); wprintf(L"%s\n",decryptedStr); // Important: RSA encryption should only be used to encrypt small amounts of data. // It is typically used for encrypting symmetric encryption // keys such that a symmetric encryption algorithm, such as // AES is then used to encrypt/decrypt bulk data CkRsaW_Dispose(rsa); CkPrivateKeyW_Dispose(key); CkRsaW_Dispose(rsaDecryptor); } |
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