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(Unicode C) Verify the RSA Signature of a SHA256 HashSee more RSA ExamplesDemonstrates how to verify an RSA signature of a SHA256 hash.
#include <C_CkPublicKeyW.h> #include <C_CkRsaW.h> #include <C_CkBinDataW.h> void ChilkatSample(void) { HCkPublicKeyW pubKey; BOOL success; HCkRsaW rsa; HCkBinDataW bdHash; HCkBinDataW bdSig; const wchar_t *enc; // This example assumes the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. // Let's say you have a file containing the 32-bytes of a SHA256 hash, // and a file that is an RSA signature of those 32 bytes. // Here's how you verify using the RSA public key found in a PEM. pubKey = CkPublicKeyW_Create(); success = CkPublicKeyW_LoadFromFile(pubKey,L"rsaPubKey.pem"); if (success == FALSE) { wprintf(L"%s\n",CkPublicKeyW_lastErrorText(pubKey)); CkPublicKeyW_Dispose(pubKey); return; } rsa = CkRsaW_Create(); // Get the public key. success = CkRsaW_ImportPublicKeyObj(rsa,pubKey); if (success == FALSE) { wprintf(L"%s\n",CkRsaW_lastErrorText(rsa)); CkPublicKeyW_Dispose(pubKey); CkRsaW_Dispose(rsa); return; } // Get the 32-byte SHA256 hash. bdHash = CkBinDataW_Create(); success = CkBinDataW_LoadFile(bdHash,L"myHash.sha256"); if (success == FALSE) { wprintf(L"Failed to load SHA256 hash.\n"); CkPublicKeyW_Dispose(pubKey); CkRsaW_Dispose(rsa); CkBinDataW_Dispose(bdHash); return; } // Get the RSA signature to be validated. bdSig = CkBinDataW_Create(); success = CkBinDataW_LoadFile(bdSig,L"mySig.sig"); if (success == FALSE) { wprintf(L"Failed to load RSA signature.\n"); CkPublicKeyW_Dispose(pubKey); CkRsaW_Dispose(rsa); CkBinDataW_Dispose(bdHash); CkBinDataW_Dispose(bdSig); return; } // Verify the signature against the SHA256 hash. enc = L"base64"; CkRsaW_putEncodingMode(rsa,enc); success = CkRsaW_VerifyHashENC(rsa,CkBinDataW_getEncoded(bdHash,enc),L"sha256",CkBinDataW_getEncoded(bdSig,enc)); if (success == FALSE) { wprintf(L"%s\n",CkRsaW_lastErrorText(rsa)); CkPublicKeyW_Dispose(pubKey); CkRsaW_Dispose(rsa); CkBinDataW_Dispose(bdHash); CkBinDataW_Dispose(bdSig); return; } wprintf(L"Signature validated.\n"); CkPublicKeyW_Dispose(pubKey); CkRsaW_Dispose(rsa); CkBinDataW_Dispose(bdHash); CkBinDataW_Dispose(bdSig); } |
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