C

Generate ECDSA Key and Get Details as XML

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Demonstrates how to generate an ECDSA key and gets the parts as XML. C

#include <C_CkEcc.h>
#include <C_CkPrng.h>
#include <C_CkPrivateKey.h>
#include <C_CkAsn.h>
#include <C_CkXml.h>
#include <C_CkCrypt2.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkEcc ecc;
    HCkPrng fortuna;
    const char *entropy;
    HCkPrivateKey privKey;
    HCkAsn asn;
    HCkXml xml;
    HCkCrypt2 crypt;
    const char *privKeyHex;

    success = FALSE;

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

    ecc = CkEcc_Create();

    // Generate a random ECC private key on the secp256k1 curve.
    // Chilkat also supports other curves, such as secp384r1, secp521r1, and secp256r1.

    // Create a Fortuna PRNG and seed it with system entropy.
    // This will be our source of random data for generating the ECC private key.
    fortuna = CkPrng_Create();
    entropy = CkPrng_getEntropy(fortuna,32,"base64");
    success = CkPrng_AddEntropy(fortuna,entropy,"base64");

    privKey = CkPrivateKey_Create();
    success = CkEcc_GenKey(ecc,"secp256k1",fortuna,privKey);
    if (success == FALSE) {
        printf("%s\n",CkEcc_lastErrorText(ecc));
        CkEcc_Dispose(ecc);
        CkPrng_Dispose(fortuna);
        CkPrivateKey_Dispose(privKey);
        return;
    }

    // An EC private key has this ASN.1
    // ECPrivateKey ::= SEQUENCE {
    //     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
    //     privateKey     OCTET STRING,
    //     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
    //     publicKey  [1] BIT STRING OPTIONAL (This is the ANSI X9.63 public key format.)

    asn = CkAsn_Create();
    success = CkAsn_LoadEncoded(asn,CkPrivateKey_getPkcs1ENC(privKey,"base64"),"base64");
    if (success != TRUE) {
        printf("%s\n",CkAsn_lastErrorText(asn));
        CkEcc_Dispose(ecc);
        CkPrng_Dispose(fortuna);
        CkPrivateKey_Dispose(privKey);
        CkAsn_Dispose(asn);
        return;
    }

    xml = CkXml_Create();
    CkXml_LoadXml(xml,CkAsn_asnToXml(asn));

    printf("%s\n",CkXml_getXml(xml));

    // The XML looks like this:
    // <?xml version="1.0" encoding="utf-8" ?>
    // <sequence>
    //     <int>01</int>
    //     <octets>JgJvBG+3wletkJab8iXAkpz0O8/AgWZSpkYVcB7SpnU=</octets>
    //     <contextSpecific tag="0" constructed="1">
    //         <oid>1.3.132.0.10</oid>
    //     </contextSpecific>
    // </sequence>

    // The 32-byte private key is in the octets..
    // Get it as hex.
    crypt = CkCrypt2_Create();
    privKeyHex = CkCrypt2_reEncode(crypt,CkXml_getChildContent(xml,"octets"),"base64","hex");

    printf("EC private key as hex = %s\n",privKeyHex);


    CkEcc_Dispose(ecc);
    CkPrng_Dispose(fortuna);
    CkPrivateKey_Dispose(privKey);
    CkAsn_Dispose(asn);
    CkXml_Dispose(xml);
    CkCrypt2_Dispose(crypt);

    }