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| Unit FGIntRSA;
Interface
Uses Windows, SysUtils, Controls, FGInt;
Procedure RSAEncrypt(P : String; Var exp, modb : TFGInt; Var E : String);
Procedure RSADecrypt(E : String; Var exp, modb, d_p, d_q, p, q : TFGInt; Var D : String);
Procedure RSASign(M : String; Var d, n, dp, dq, p, q : TFGInt; Var S : String);
Procedure RSAVerify(M, S : String; Var e, n : TFGInt; Var valid : boolean);
Implementation
{$H+}
// Encrypt a string with the RSA algorithm, P^exp mod modb = E
Procedure RSAEncrypt(P : String; Var exp, modb : TFGInt; Var E : String);
Var
i, j, modbits : longint;
PGInt, temp, zero : TFGInt;
tempstr1, tempstr2, tempstr3 : String;
Begin
Base2StringToFGInt('0', zero);
FGIntToBase2String(modb, tempstr1);
modbits := length(tempstr1);
convertBase256to2(P, tempstr1);
tempstr1 := '111' + tempstr1;
j := modbits - 1;
While (length(tempstr1) Mod j) <> 0 Do tempstr1 := '0' + tempstr1;
j := length(tempstr1) Div (modbits - 1);
tempstr2 := '';
For i := 1 To j Do
Begin
tempstr3 := copy(tempstr1, 1, modbits - 1);
While (copy(tempstr3, 1, 1) = '0') And (length(tempstr3) > 1) Do delete(tempstr3, 1, 1);
Base2StringToFGInt(tempstr3, PGInt);
delete(tempstr1, 1, modbits - 1);
If tempstr3 = '0' Then FGIntCopy(zero, temp) Else FGIntMontgomeryModExp(PGInt, exp, modb, temp);
FGIntDestroy(PGInt);
tempstr3 := '';
FGIntToBase2String(temp, tempstr3);
While (length(tempstr3) Mod modbits) <> 0 Do tempstr3 := '0' + tempstr3;
tempstr2 := tempstr2 + tempstr3;
FGIntdestroy(temp);
End;
While (tempstr2[1] = '0') And (length(tempstr2) > 1) Do delete(tempstr2, 1, 1);
ConvertBase2To256(tempstr2, E);
FGIntDestroy(zero);
End;
// Decrypt a string with the RSA algorithm, E^exp mod modb = D
// provide nil for exp.Number if you want a speedup by using the chinese
// remainder theorem, modb = p*q, d_p*e mod (p-1) = 1 and
// d_q*e mod (q-1) where e is the encryption exponent used
Procedure RSADecrypt(E : String; Var exp, modb, d_p, d_q, p, q : TFGInt; Var D : String);
Var
i, j, modbits : longint;
EGInt, temp, temp1, temp2, temp3, ppinvq, qqinvp, zero : TFGInt;
tempstr1, tempstr2, tempstr3 : String;
Begin
Base2StringToFGInt('0', zero);
FGIntToBase2String(modb, tempstr1);
modbits := length(tempstr1);
convertBase256to2(E, tempstr1);
While copy(tempstr1, 1, 1) = '0' Do delete(tempstr1, 1, 1);
While (length(tempstr1) Mod modbits) <> 0 Do tempstr1 := '0' + tempstr1;
If exp.Number = Nil Then
Begin
FGIntModInv(q, p, temp1);
FGIntMul(q, temp1, qqinvp);
FGIntDestroy(temp1);
FGIntModInv(p, q, temp1);
FGIntMul(p, temp1, ppinvq);
FGIntDestroy(temp1);
End;
j := length(tempstr1) Div modbits;
tempstr2 := '';
For i := 1 To j Do
Begin
tempstr3 := copy(tempstr1, 1, modbits);
While (copy(tempstr3, 1, 1) = '0') And (length(tempstr3) > 1) Do delete(tempstr3, 1, 1);
Base2StringToFGInt(tempstr3, EGInt);
delete(tempstr1, 1, modbits);
If tempstr3 = '0' Then FGIntCopy(zero, temp) Else
Begin
If exp.Number <> Nil Then FGIntMontgomeryModExp(EGInt, exp, modb, temp) Else
Begin
FGIntMontgomeryModExp(EGInt, d_p, p, temp1);
FGIntMul(temp1, qqinvp, temp3);
FGIntCopy(temp3, temp1);
FGIntMontgomeryModExp(EGInt, d_q, q, temp2);
FGIntMul(temp2, ppinvq, temp3);
FGIntCopy(temp3, temp2);
FGIntAddMod(temp1, temp2, modb, temp);
FGIntDestroy(temp1);
FGIntDestroy(temp2);
End;
End;
FGIntDestroy(EGInt);
tempstr3 := '';
FGIntToBase2String(temp, tempstr3);
While (length(tempstr3) Mod (modbits - 1)) <> 0 Do tempstr3 := '0' + tempstr3;
tempstr2 := tempstr2 + tempstr3;
FGIntdestroy(temp);
End;
If exp.Number = Nil Then
Begin
FGIntDestroy(ppinvq);
FGIntDestroy(qqinvp);
End;
While (Not (copy(tempstr2, 1, 3) = '111')) And (length(tempstr2) > 3) Do delete(tempstr2, 1, 1);
delete(tempstr2, 1, 3);
ConvertBase2To256(tempstr2, D);
FGIntDestroy(zero);
End;
// Sign strings with the RSA algorithm, M^d mod n = S
// provide nil for exp.Number if you want a speedup by using the chinese
// remainder theorem, n = p*q, dp*e mod (p-1) = 1 and
// dq*e mod (q-1) where e is the encryption exponent used
Procedure RSASign(M : String; Var d, n, dp, dq, p, q : TFGInt; Var S : String);
Var
MGInt, SGInt, temp, temp1, temp2, temp3, ppinvq, qqinvp : TFGInt;
Begin
Base256StringToFGInt(M, MGInt);
If d.Number <> Nil Then FGIntMontgomeryModExp(MGInt, d, n, SGInt) Else
Begin
FGIntModInv(p, q, temp);
FGIntMul(p, temp, ppinvq);
FGIntDestroy(temp);
FGIntModInv(q, p, temp);
FGIntMul(q, temp, qqinvp);
FGIntDestroy(temp);
FGIntMontgomeryModExp(MGInt, dp, p, temp1);
FGIntMul(temp1, qqinvp, temp2);
FGIntCopy(temp2, temp1);
FGIntMontgomeryModExp(MGInt, dq, q, temp2);
FGIntMul(temp2, ppinvq, temp3);
FGIntCopy(temp3, temp2);
FGIntAddMod(temp1, temp2, n, SGInt);
FGIntDestroy(temp1);
FGIntDestroy(temp2);
FGIntDestroy(ppinvq);
FGIntDestroy(qqinvp);
End;
FGIntToBase256String(SGInt, S);
FGIntDestroy(MGInt);
FGIntDestroy(SGInt);
End;
// Verify digitally signed strings with the RSA algorihthm,
// If M = S^e mod n then ok:=true else ok:=false
Procedure RSAVerify(M, S : String; Var e, n : TFGInt; Var valid : boolean);
Var
MGInt, SGInt, temp : TFGInt;
Begin
Base256StringToFGInt(S, SGInt);
Base256StringToFGInt(M, MGInt);
FGIntMod(MGInt, n, temp);
FGIntCopy(temp, MGInt);
FGIntMontgomeryModExp(SGInt, e, n, temp);
FGIntCopy(temp, SGInt);
valid := (FGIntCompareAbs(SGInt, MGInt) = Eq);
FGIntDestroy(SGInt);
FGIntDestroy(MGInt);
End;
End. |
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Сообщение от Nutserus
