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(Unicode C) Create ECSDA Signature using Raw r and s Format (not ASN.1)See more ECC ExamplesDemonstrates how to create an ECDSA signature using the raw r/s format. ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:
(a) Concatenating the raw byte array of r and s This example demonstrates how to create a signature that is a byte array of r and s concatenated. Note: This example requires Chilkat v9.5.0.97 or greater.
#include <C_CkStringBuilderW.h> #include <C_CkPrivateKeyW.h> #include <C_CkPrngW.h> #include <C_CkEccW.h> #include <C_CkPublicKeyW.h> void ChilkatSample(void) { HCkStringBuilderW sb; const wchar_t *hash; HCkPrivateKeyW privKey; BOOL success; HCkPrngW prng; HCkEccW ecdsa; const wchar_t *ecdsaSigBase64; HCkPublicKeyW pubKey; int result; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. // To create an ECDSA signature, the data first needs to be hashed. Then the hash // is signed. sb = CkStringBuilderW_Create(); CkStringBuilderW_Append(sb,L"The quick brown fox jumps over the lazy dog"); hash = CkStringBuilderW_getHash(sb,L"sha256",L"base64",L"utf-8"); // Load the ECDSA key to be used for signing. privKey = CkPrivateKeyW_Create(); success = CkPrivateKeyW_LoadPemFile(privKey,L"qa_data/ecc/secp256r1-key-pkcs8.pem"); if (success != TRUE) { wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(privKey)); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); return; } prng = CkPrngW_Create(); ecdsa = CkEccW_Create(); // Produce a signature that is not ASN.1, but is instead the concatenation // of the raw r and s signature parts. // This feature was added in Chilkat v9.5.0.97 CkEccW_putAsnFormat(ecdsa,FALSE); ecdsaSigBase64 = CkEccW_signHashENC(ecdsa,hash,L"base64",privKey,prng); if (CkEccW_getLastMethodSuccess(ecdsa) != TRUE) { wprintf(L"%s\n",CkEccW_lastErrorText(ecdsa)); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); return; } wprintf(L"ECDSA signature = %s\n",ecdsaSigBase64); // ----------------------------------------------------------- // Now let's verify the signature using the public key. pubKey = CkPublicKeyW_Create(); success = CkPublicKeyW_LoadFromFile(pubKey,L"qa_data/ecc/secp256r1-pubkey.pem"); if (success != TRUE) { wprintf(L"%s\n",CkPublicKeyW_lastErrorText(pubKey)); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); CkPublicKeyW_Dispose(pubKey); return; } // Note: When verifying, Chilkat will auto-detect the format for both kinds of ECDSA signatures (ASN.1 or binary r+s) result = CkEccW_VerifyHashENC(ecdsa,hash,ecdsaSigBase64,L"base64",pubKey); if (result == 1) { wprintf(L"Signature is valid.\n"); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); CkPublicKeyW_Dispose(pubKey); return; } if (result == 0) { wprintf(L"Signature is invalid.\n"); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); CkPublicKeyW_Dispose(pubKey); return; } if (result < 0) { wprintf(L"%s\n",CkEccW_lastErrorText(ecdsa)); wprintf(L"The VerifyHashENC method call failed.\n"); CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); CkPublicKeyW_Dispose(pubKey); return; } CkStringBuilderW_Dispose(sb); CkPrivateKeyW_Dispose(privKey); CkPrngW_Dispose(prng); CkEccW_Dispose(ecdsa); CkPublicKeyW_Dispose(pubKey); } |
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