ext/ipp/sources/ippcp/pcprsa_emsa_pkcs1v15.h

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/*
//
//  Purpose:
//     Cryptography Primitive.
//     RSASSA-PKCS-v1_5
//
*/

#include "owndefs.h"
#include "owncp.h"
#include "pcpngrsa.h"
#include "pcphash.h"
#include "pcptool.h"

static int EMSA_PKCSv15(const Ipp8u* msgDg, int lenMsgDg,
    const Ipp8u* fixPS, int lenFixPS,
    Ipp8u*   pEM, int lenEM)
{
    /*
    // encoded message format:
    //    EM = 00 || 01 || PS=(FF..FF) || 00 || T
    //    T = fixPS || msgDg
    //    len(PS) >= 8
    */
    int  tLen = lenFixPS + lenMsgDg;

    if (lenEM >= tLen + 11) {
        int psLen = lenEM - 3 - tLen;

        PaddBlock(0xFF, pEM, lenEM);
        pEM[0] = 0x00;
        pEM[1] = 0x01;
        pEM[2 + psLen] = 0x00;
        CopyBlock(fixPS, pEM + 3 + psLen, lenFixPS);
        CopyBlock(msgDg, pEM + 3 + psLen + lenFixPS, lenMsgDg);
        return 1;
    }
    else
        return 0; /* encoded message length too long */
}