(C) Ed25519 Sign and Verify

Demonstrates how to create an Ed25519 signature, and then to verify it.

Note: This example requires Chilkat v9.5.0.83 or greater.

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#include <C_CkPrivateKey.h>
#include <C_CkBinData.h>
#include <C_CkEdDSA.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    const char *privKeyHex;
    const char *pubKeyHex;
    HCkPrivateKey privKey;
    BOOL success;
    HCkBinData bd;
    HCkEdDSA eddsa;
    const char *hexSig;
    HCkPublicKey pubKey;
    BOOL bVerified;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    privKeyHex = "1498b5467a63dffa2dc9d9e069caf075d16fc33fdd4c3b01bfadae6433767d93";
    pubKeyHex = "b7a3c12dc0c8c748ab07525b701122b88bd78f600c76342d27f25e5f92444cde";

    privKey = CkPrivateKey_Create();
    // This example shows only one way of loading an Ed25519 private key.
    // Chilkat can load other formats (JWK, PEM, ASN.1 DER, etc.)  
    // You may do so by calling LoadAnyFormat or LoadAnyFormatFile.
    success = CkPrivateKey_LoadEd25519(privKey,privKeyHex,pubKeyHex);
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkPrivateKey_Dispose(privKey);
        return;
    }

    // The data to be signed...
    bd = CkBinData_Create();
    CkBinData_AppendString(bd,"Message for Ed25519 signing","utf-8");

    eddsa = CkEdDSA_Create();
    hexSig = CkEdDSA_signBdENC(eddsa,bd,"hexlower",privKey);

    printf("signature = %s\n",hexSig);

    // The expected output is: 6dd355667fae4eb43c6e0ab92e870edb2de0a88cae12dbd8591507f584fe4912babff497f1b8edf9567d2483d54ddc6459bea7855281b7a246a609e3001a4e08

    // Verify the signature..
    pubKey = CkPublicKey_Create();
    success = CkPublicKey_LoadEd25519(pubKey,pubKeyHex);
    if (success == FALSE) {
        printf("%s\n",CkPublicKey_lastErrorText(pubKey));
        CkPrivateKey_Dispose(privKey);
        CkBinData_Dispose(bd);
        CkEdDSA_Dispose(eddsa);
        CkPublicKey_Dispose(pubKey);
        return;
    }

    bVerified = CkEdDSA_VerifyBdENC(eddsa,bd,hexSig,"hexlower",pubKey);
    if (bVerified == FALSE) {
        printf("%s\n",CkEdDSA_lastErrorText(eddsa));
        printf("Failed to verify the signature.\n");
        CkPrivateKey_Dispose(privKey);
        CkBinData_Dispose(bd);
        CkEdDSA_Dispose(eddsa);
        CkPublicKey_Dispose(pubKey);
        return;
    }

    printf("The Ed25519 signature is verified!\n");


    CkPrivateKey_Dispose(privKey);
    CkBinData_Dispose(bd);
    CkEdDSA_Dispose(eddsa);
    CkPublicKey_Dispose(pubKey);

    }