C++ Class Implementation of HMAC-SHA

string apiKey = "1234";
string payload = "4321";


byte[] bKey = Encoding.Default.GetBytes(apiKey);
byte[] bPayload = Encoding.Default.GetBytes(payload);

HMACSHA1 hmacSha = new HMACSHA1(bKey, true);
hmacSha.Initialize();
byte[] bytes = hmacSha.ComputeHash(bPayload);

string signature = BitConverter.ToString(bytes).Replace("-", string.Empty);
Console.WriteLine(signature);

BYTE Key[20] ;
BYTE digest[20] ;
BYTE input[20];

printf("%d",sizeof(Key));

memset(Key, 0, 20);
memset(input,0,20);

int count = 0;
char *test = "4321";
for (char *s = test; strlen(s)>0; s+=2)
{
    if(*s>='0' && *s<='9')
        input[count]=*s-'0';
    else if(*s>='a'&& *s<='f')
        input[count]=*s-'a'+10;
    if(strlen(s)>1)
    {
        input[count]*=16;
        if(*(s+1)>='0' && *(s+1)<='9') input[count]+=(*(s+1)-'0');
        if(*(s+1)>='a'&& *(s+1)<='f') input[count]+=(*(s+1)-'a'+10);
    }
    count++;
}

count = 0;
char * strkey = "1234";
for (char *s1 = strkey; strlen(s1)>0; s1+=2)
{
    if(*s1>='0' && *s1<='9')
        Key[count]=*s1-'0';
    else if(*s1>='a'&& *s1<='f')
        Key[count]=*s1-'a'+10;
    if(strlen(s1)>1)
    {
            Key[count]*=16;
            if(*(s1+1)>='0' && *(s1+1)<='9') Key[count]+=(*(s1+1)-'0');
            if(*(s1+1)>='a'&& *(s1+1)<='f') Key[count]+=(*(s1+1)-'a'+10);
    }
    count++;
}

CHMAC_SHA1 HMAC_SHA1 ;
HMAC_SHA1.HMAC_SHA1(input, 2, Key, 2, digest) ;

char temp[41];

memset(temp,0,41);

int i = 0;
for (i = 0; i<20;i++)
{
    sprintf(temp+i*2,"%02X",digest[i]);
}
printf ("%s",temp);