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1 /* |
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2 * Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of the License "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * |
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16 */ |
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17 |
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18 |
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19 /** |
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20 @file |
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21 */ |
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22 |
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23 #include "pkcs5kdf.h" |
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24 |
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25 /* Before complaining about the variable names in this file, |
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26 * read the pkcs5 spec and all will become clear. |
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27 */ |
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28 |
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29 EXPORT_C void TPKCS5KDF::DeriveKeyL(TDes8& aKey, const TDesC8& aPasswd, const TDesC8& aSalt, |
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30 const TUint aIterations) |
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31 { |
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32 CSHA1* sha1 = CSHA1::NewL(); |
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33 CleanupStack::PushL(sha1); |
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34 CHMAC* hmac = CHMAC::NewL(aPasswd, sha1); |
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35 CleanupStack::Pop(sha1); //hmac now owns it |
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36 CleanupStack::PushL(hmac); |
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37 |
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38 TUint hashBytes = hmac->HashSize(); |
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39 TUint c = aIterations; |
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40 TUint l = aKey.Length() / hashBytes; |
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41 if(aKey.Length() % hashBytes != 0) //round up if mod !=0 |
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42 { |
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43 l+=1; |
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44 } |
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45 TUint r = aKey.Length() - (l-1) * hashBytes; //r == length of last block |
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46 |
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47 HBufC8* TiTemp = HBufC8::NewLC(hashBytes); |
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48 TUint32* Ti = (TUint32*)(TiTemp->Ptr()); |
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49 aKey.SetLength(0); //we've already saved the length we want |
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50 |
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51 HBufC8* STemp = HBufC8::NewLC(aSalt.Length() + sizeof(TUint32)); |
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52 TUint32* S = (TUint32*)(STemp->Ptr()); |
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53 |
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54 HBufC8* UiTemp = HBufC8::NewLC(hashBytes); |
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55 TUint32* Ui = (TUint32*)(UiTemp->Ptr()); |
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56 |
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57 const TUint32* salt = (TUint32*)(aSalt.Ptr()); |
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58 TUint saltBytes = aSalt.Length(); |
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59 |
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60 for(TUint i = 1; i<=l; i++) |
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61 { |
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62 F(*hmac, Ti, S, Ui, hashBytes, salt, saltBytes, c, i); |
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63 if(i == l) |
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64 aKey.Append((TUint8*)Ti, r); |
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65 else |
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66 aKey.Append((TUint8*)Ti, hashBytes); |
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67 } |
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68 |
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69 CleanupStack::PopAndDestroy(UiTemp); |
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70 CleanupStack::PopAndDestroy(STemp); |
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71 CleanupStack::PopAndDestroy(TiTemp); |
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72 CleanupStack::PopAndDestroy(hmac); |
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73 } |
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74 |
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75 void TPKCS5KDF::F(CMessageDigest& aDigest, TUint32* aAccumulator, |
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76 TUint32* S, TUint32* Ui, TUint aHashBytes, const TUint32* aSalt, |
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77 TUint aSaltBytes, TUint c, TUint i) |
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78 { |
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79 TUint8 itmp[4]; |
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80 itmp[0] = (TUint8)((i >> 24) & 0xff); |
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81 itmp[1] = (TUint8)((i >> 16) & 0xff); |
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82 itmp[2] = (TUint8)((i >> 8) & 0xff); |
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83 itmp[3] = (TUint8)(i & 0xff); |
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84 TUint8* endOfS = Mem::Copy(S, aSalt, aSaltBytes); |
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85 Mem::Copy((TUint32*)endOfS, (TUint32*)&itmp, 4); |
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86 |
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87 TPtr8 sptr((TUint8*)S, aSaltBytes+4); |
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88 sptr.SetLength(aSaltBytes+4); |
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89 Mem::Copy(aAccumulator, (TUint32*)((aDigest.Final(sptr)).Ptr()),aHashBytes); |
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90 Mem::Copy(Ui, aAccumulator, aHashBytes); |
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91 |
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92 for(TUint j=1; j<c; j++) |
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93 { |
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94 TPtr8 uiptr((TUint8*)Ui, aHashBytes); |
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95 uiptr.SetLength(aHashBytes); |
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96 Mem::Copy(Ui, (TUint32*)((aDigest.Final(uiptr)).Ptr()), aHashBytes); |
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97 XORString(Ui, aAccumulator, aHashBytes); |
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98 } |
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99 } |
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100 |
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101 inline void TPKCS5KDF::XORString(const TUint32* aOp1, TUint32* aOp2, |
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102 TUint aLength) |
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103 { |
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104 const TUint32* i = aOp1; |
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105 |
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106 //this will overflow the whole final word if aLength % 4 != 0 |
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107 //but I can't see this mattering cuz all memory allocation is on a word by word basis |
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108 //i don't want to do this byte by byte as it'll be way slower |
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109 //also, every sane digest is going to be a multiple of 4 -- so this isn't a problem |
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110 for( ; aOp1 != (TUint32*)((TUint8*)i + aLength); ) |
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111 { |
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112 *aOp2++ ^= *aOp1++; |
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113 } |
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114 } |
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115 |