(C) Ed25519ph Sign and Verify

Demonstrates how to create an Ed25519ph signature, and then to verify it.

Note: This example requires Chilkat v9.5.0.91 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.

    // Use the following test vector from https://www.rfc-editor.org/rfc/rfc8032#page-30

    //    -----TEST abc
    // 
    //    ALGORITHM:
    //    Ed25519ph
    // 
    //    SECRET KEY:
    //    833fe62409237b9d62ec77587520911e
    //    9a759cec1d19755b7da901b96dca3d42
    // 
    //    PUBLIC KEY:
    //    ec172b93ad5e563bf4932c70e1245034
    //    c35467ef2efd4d64ebf819683467e2bf
    // 
    //    MESSAGE (length 3 bytes):
    //    616263
    // 
    //    SIGNATURE:
    //    98a70222f0b8121aa9d30f813d683f80
    //    9e462b469c7ff87639499bb94e6dae41
    //    31f85042463c2a355a2003d062adf5aa
    //    a10b8c61e636062aaad11c2a26083406

    privKeyHex = "833fe62409237b9d62ec77587520911e9a759cec1d19755b7da901b96dca3d42";
    pubKeyHex = "ec172b93ad5e563bf4932c70e1245034c35467ef2efd4d64ebf819683467e2bf";

    privKey = CkPrivateKey_Create();
    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_AppendEncoded(bd,"616263","hex");

    eddsa = CkEdDSA_Create();
    // Indicate we want the Ed25519ph instance.
    CkEdDSA_putAlgorithm(eddsa,"Ed25519ph");

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

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

    // The expected output is: 98a70222f0b8121aa9d30f813d683f80....

    // 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 Ed25519ph signature is verified!\n");


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

    }