summary refs log tree commit diff
path: root/crypto/src/openpgp/PgpSecretKey.cs
blob: b3986073dd2a3c95d9e9e8809fc50ffa4e2549d2 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
using System;
using System.Collections;
using System.IO;

using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Bcpg.OpenPgp
{
    /// <remarks>General class to handle a PGP secret key object.</remarks>
    public class PgpSecretKey
    {
        private readonly SecretKeyPacket	secret;
        private readonly PgpPublicKey		pub;

        internal PgpSecretKey(
            SecretKeyPacket	secret,
            PgpPublicKey	pub)
        {
            this.secret = secret;
            this.pub = pub;
        }

        internal PgpSecretKey(
            PgpPrivateKey				privKey,
            PgpPublicKey				pubKey,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            byte[]						rawPassPhrase,
            bool                        clearPassPhrase,
            bool						useSha1,
            SecureRandom				rand,
            bool						isMasterKey)
        {
            BcpgObject secKey;

            this.pub = pubKey;

            switch (pubKey.Algorithm)
            {
                case PublicKeyAlgorithmTag.RsaEncrypt:
                case PublicKeyAlgorithmTag.RsaSign:
                case PublicKeyAlgorithmTag.RsaGeneral:
                    RsaPrivateCrtKeyParameters rsK = (RsaPrivateCrtKeyParameters) privKey.Key;
                    secKey = new RsaSecretBcpgKey(rsK.Exponent, rsK.P, rsK.Q);
                    break;
                case PublicKeyAlgorithmTag.Dsa:
                    DsaPrivateKeyParameters dsK = (DsaPrivateKeyParameters) privKey.Key;
                    secKey = new DsaSecretBcpgKey(dsK.X);
                    break;
                case PublicKeyAlgorithmTag.ECDH:
                case PublicKeyAlgorithmTag.ECDsa:
                    ECPrivateKeyParameters ecK = (ECPrivateKeyParameters)privKey.Key;
                    secKey = new ECSecretBcpgKey(ecK.D);
                    break;
                case PublicKeyAlgorithmTag.ElGamalEncrypt:
                case PublicKeyAlgorithmTag.ElGamalGeneral:
                    ElGamalPrivateKeyParameters esK = (ElGamalPrivateKeyParameters) privKey.Key;
                    secKey = new ElGamalSecretBcpgKey(esK.X);
                    break;
                default:
                    throw new PgpException("unknown key class");
            }

            try
            {
                MemoryStream bOut = new MemoryStream();
                BcpgOutputStream pOut = new BcpgOutputStream(bOut);

                pOut.WriteObject(secKey);

                byte[] keyData = bOut.ToArray();
                byte[] checksumData = Checksum(useSha1, keyData, keyData.Length);

                keyData = Arrays.Concatenate(keyData, checksumData);

                if (encAlgorithm == SymmetricKeyAlgorithmTag.Null)
                {
                    if (isMasterKey)
                    {
                        this.secret = new SecretKeyPacket(pub.publicPk, encAlgorithm, null, null, keyData);
                    }
                    else
                    {
                        this.secret = new SecretSubkeyPacket(pub.publicPk, encAlgorithm, null, null, keyData);
                    }
                }
                else
                {
                    S2k s2k;
                    byte[] iv;

                    byte[] encData;
                    if (pub.Version >= 4)
                    {
                        encData = EncryptKeyDataV4(keyData, encAlgorithm, HashAlgorithmTag.Sha1, rawPassPhrase, clearPassPhrase, rand, out s2k, out iv);
                    }
                    else
                    {
                        encData = EncryptKeyDataV3(keyData, encAlgorithm, rawPassPhrase, clearPassPhrase, rand, out s2k, out iv);
                    }

                    int s2kUsage = useSha1
                        ?	SecretKeyPacket.UsageSha1
                        :	SecretKeyPacket.UsageChecksum;

                    if (isMasterKey)
                    {
                        this.secret = new SecretKeyPacket(pub.publicPk, encAlgorithm, s2kUsage, s2k, iv, encData);
                    }
                    else
                    {
                        this.secret = new SecretSubkeyPacket(pub.publicPk, encAlgorithm, s2kUsage, s2k, iv, encData);
                    }
                }
            }
            catch (PgpException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new PgpException("Exception encrypting key", e);
            }
        }

        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        [Obsolete("Use the constructor taking an explicit 'useSha1' parameter instead")]
        public PgpSecretKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            char[]						passPhrase,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, passPhrase, false, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public PgpSecretKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            char[]						passPhrase,
            bool						useSha1,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, false, passPhrase, useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <remarks>
        /// If utf8PassPhrase is true, conversion of the passphrase to bytes uses Encoding.UTF8.GetBytes(), otherwise the conversion
        /// is performed using Convert.ToByte(), which is the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public PgpSecretKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            bool                        utf8PassPhrase,
            char[]						passPhrase,
            bool						useSha1,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel, keyPair, id, encAlgorithm,
                PgpUtilities.EncodePassPhrase(passPhrase, utf8PassPhrase), true,
                useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        public PgpSecretKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            byte[]						rawPassPhrase,
            bool						useSha1,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, rawPassPhrase, false, useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        internal PgpSecretKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            byte[]						rawPassPhrase,
            bool                        clearPassPhrase,
            bool						useSha1,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(keyPair.PrivateKey, CertifiedPublicKey(certificationLevel, keyPair, id, hashedPackets, unhashedPackets),
                encAlgorithm, rawPassPhrase, clearPassPhrase, useSha1, rand, true)
        {
        }

        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public PgpSecretKey(
            int                         certificationLevel,
            PgpKeyPair                  keyPair,
            string                      id,
            SymmetricKeyAlgorithmTag    encAlgorithm,
            HashAlgorithmTag            hashAlgorithm,
            char[]                      passPhrase,
            bool                        useSha1,
            PgpSignatureSubpacketVector hashedPackets,
            PgpSignatureSubpacketVector unhashedPackets,
            SecureRandom                rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, hashAlgorithm, false, passPhrase, useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <remarks>
        /// If utf8PassPhrase is true, conversion of the passphrase to bytes uses Encoding.UTF8.GetBytes(), otherwise the conversion
        /// is performed using Convert.ToByte(), which is the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public PgpSecretKey(
            int                         certificationLevel,
            PgpKeyPair                  keyPair,
            string                      id,
            SymmetricKeyAlgorithmTag    encAlgorithm,
            HashAlgorithmTag            hashAlgorithm,
            bool                        utf8PassPhrase,
            char[]                      passPhrase,
            bool                        useSha1,
            PgpSignatureSubpacketVector hashedPackets,
            PgpSignatureSubpacketVector unhashedPackets,
            SecureRandom                rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, hashAlgorithm,
                PgpUtilities.EncodePassPhrase(passPhrase, utf8PassPhrase), true,
                useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        public PgpSecretKey(
            int                         certificationLevel,
            PgpKeyPair                  keyPair,
            string                      id,
            SymmetricKeyAlgorithmTag    encAlgorithm,
            HashAlgorithmTag            hashAlgorithm,
            byte[]                      rawPassPhrase,
            bool                        useSha1,
            PgpSignatureSubpacketVector hashedPackets,
            PgpSignatureSubpacketVector unhashedPackets,
            SecureRandom                rand)
            : this(certificationLevel, keyPair, id, encAlgorithm, hashAlgorithm, rawPassPhrase, false, useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        internal PgpSecretKey(
            int                         certificationLevel,
            PgpKeyPair                  keyPair,
            string                      id,
            SymmetricKeyAlgorithmTag    encAlgorithm,
            HashAlgorithmTag            hashAlgorithm,
            byte[]                      rawPassPhrase,
            bool                        clearPassPhrase,
            bool                        useSha1,
            PgpSignatureSubpacketVector hashedPackets,
            PgpSignatureSubpacketVector unhashedPackets,
            SecureRandom                rand)
            : this(keyPair.PrivateKey, CertifiedPublicKey(certificationLevel, keyPair, id, hashedPackets, unhashedPackets, hashAlgorithm),
                encAlgorithm, rawPassPhrase, clearPassPhrase, useSha1, rand, true)
        {
        }

        private static PgpPublicKey CertifiedPublicKey(
            int							certificationLevel,
            PgpKeyPair					keyPair,
            string						id,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets)
        {
            PgpSignatureGenerator sGen;
            try
            {
                sGen = new PgpSignatureGenerator(keyPair.PublicKey.Algorithm, HashAlgorithmTag.Sha1);
            }
            catch (Exception e)
            {
                throw new PgpException("Creating signature generator: " + e.Message, e);
            }

            //
            // Generate the certification
            //
            sGen.InitSign(certificationLevel, keyPair.PrivateKey);

            sGen.SetHashedSubpackets(hashedPackets);
            sGen.SetUnhashedSubpackets(unhashedPackets);

            try
            {
                PgpSignature certification = sGen.GenerateCertification(id, keyPair.PublicKey);
                return PgpPublicKey.AddCertification(keyPair.PublicKey, id, certification);
            }
            catch (Exception e)
            {
                throw new PgpException("Exception doing certification: " + e.Message, e);
            }
        }


        private static PgpPublicKey CertifiedPublicKey(
            int certificationLevel,
            PgpKeyPair keyPair,
            string id,
            PgpSignatureSubpacketVector hashedPackets,
            PgpSignatureSubpacketVector unhashedPackets,
            HashAlgorithmTag hashAlgorithm)
        {
            PgpSignatureGenerator sGen;
            try
            {
                sGen = new PgpSignatureGenerator(keyPair.PublicKey.Algorithm, hashAlgorithm);
            }
            catch (Exception e)
            {
                throw new PgpException("Creating signature generator: " + e.Message, e);
            }

            //
            // Generate the certification
            //
            sGen.InitSign(certificationLevel, keyPair.PrivateKey);

            sGen.SetHashedSubpackets(hashedPackets);
            sGen.SetUnhashedSubpackets(unhashedPackets);

            try
            {
                PgpSignature certification = sGen.GenerateCertification(id, keyPair.PublicKey);
                return PgpPublicKey.AddCertification(keyPair.PublicKey, id, certification);
            }
            catch (Exception e)
            {
                throw new PgpException("Exception doing certification: " + e.Message, e);
            }
        }

        public PgpSecretKey(
            int							certificationLevel,
            PublicKeyAlgorithmTag		algorithm,
            AsymmetricKeyParameter		pubKey,
            AsymmetricKeyParameter		privKey,
            DateTime					time,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            char[]						passPhrase,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel,
                new PgpKeyPair(algorithm, pubKey, privKey, time),
                id, encAlgorithm, passPhrase, false, hashedPackets, unhashedPackets, rand)
        {
        }

        public PgpSecretKey(
            int							certificationLevel,
            PublicKeyAlgorithmTag		algorithm,
            AsymmetricKeyParameter		pubKey,
            AsymmetricKeyParameter		privKey,
            DateTime					time,
            string						id,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            char[]						passPhrase,
            bool						useSha1,
            PgpSignatureSubpacketVector	hashedPackets,
            PgpSignatureSubpacketVector	unhashedPackets,
            SecureRandom				rand)
            : this(certificationLevel, new PgpKeyPair(algorithm, pubKey, privKey, time), id, encAlgorithm, passPhrase, useSha1, hashedPackets, unhashedPackets, rand)
        {
        }

        /// <summary>
        /// Check if this key has an algorithm type that makes it suitable to use for signing.
        /// </summary>
        /// <remarks>
        /// Note: with version 4 keys KeyFlags subpackets should also be considered when present for
        /// determining the preferred use of the key.
        /// </remarks>
        /// <returns>
        /// <c>true</c> if this key algorithm is suitable for use with signing.
        /// </returns>
        public bool IsSigningKey
        {
            get
            {
                switch (pub.Algorithm)
                {
                    case PublicKeyAlgorithmTag.RsaGeneral:
                    case PublicKeyAlgorithmTag.RsaSign:
                    case PublicKeyAlgorithmTag.Dsa:
                    case PublicKeyAlgorithmTag.ECDsa:
                    case PublicKeyAlgorithmTag.ElGamalGeneral:
                        return true;
                    default:
                        return false;
                }
            }
        }

        /// <summary>True, if this is a master key.</summary>
        public bool IsMasterKey
        {
            get { return pub.IsMasterKey; }
        }

        /// <summary>Detect if the Secret Key's Private Key is empty or not</summary>
        public bool IsPrivateKeyEmpty
        {
            get
            {
                byte[] secKeyData = secret.GetSecretKeyData();

                return secKeyData == null || secKeyData.Length < 1;
            }
        }

        /// <summary>The algorithm the key is encrypted with.</summary>
        public SymmetricKeyAlgorithmTag KeyEncryptionAlgorithm
        {
            get { return secret.EncAlgorithm; }
        }

        /// <summary>The key ID of the public key associated with this key.</summary>
        public long KeyId
        {
            get { return pub.KeyId; }
        }

        /// <summary>Return the S2K usage associated with this key.</summary>
        public int S2kUsage
        {
            get { return secret.S2kUsage; }
        }

        /// <summary>Return the S2K used to process this key.</summary>
        public S2k S2k
        {
            get { return secret.S2k; }
        }

        /// <summary>The public key associated with this key.</summary>
        public PgpPublicKey PublicKey
        {
            get { return pub; }
        }

        /// <summary>Allows enumeration of any user IDs associated with the key.</summary>
        /// <returns>An <c>IEnumerable</c> of <c>string</c> objects.</returns>
        public IEnumerable UserIds
        {
            get { return pub.GetUserIds(); }
        }

        /// <summary>Allows enumeration of any user attribute vectors associated with the key.</summary>
        /// <returns>An <c>IEnumerable</c> of <c>string</c> objects.</returns>
        public IEnumerable UserAttributes
        {
            get { return pub.GetUserAttributes(); }
        }

        private byte[] ExtractKeyData(byte[] rawPassPhrase, bool clearPassPhrase)
        {
            SymmetricKeyAlgorithmTag encAlgorithm = secret.EncAlgorithm;
            byte[] encData = secret.GetSecretKeyData();

            if (encAlgorithm == SymmetricKeyAlgorithmTag.Null)
                // TODO Check checksum here?
                return encData;

            // TODO Factor this block out as 'decryptData'
            try
            {
                KeyParameter key = PgpUtilities.DoMakeKeyFromPassPhrase(secret.EncAlgorithm, secret.S2k, rawPassPhrase, clearPassPhrase);
                byte[] iv = secret.GetIV();
                byte[] data;

                if (secret.PublicKeyPacket.Version >= 4)
                {
                    data = RecoverKeyData(encAlgorithm, "/CFB/NoPadding", key, iv, encData, 0, encData.Length);

                    bool useSha1 = secret.S2kUsage == SecretKeyPacket.UsageSha1;
                    byte[] check = Checksum(useSha1, data, (useSha1) ? data.Length - 20 : data.Length - 2);

                    for (int i = 0; i != check.Length; i++)
                    {
                        if (check[i] != data[data.Length - check.Length + i])
                        {
                            throw new PgpException("Checksum mismatch at " + i + " of " + check.Length);
                        }
                    }
                }
                else // version 2 or 3, RSA only.
                {
                    data = new byte[encData.Length];

                    iv = Arrays.Clone(iv);

                    //
                    // read in the four numbers
                    //
                    int pos = 0;

                    for (int i = 0; i != 4; i++)
                    {
                        int encLen = (((encData[pos] << 8) | (encData[pos + 1] & 0xff)) + 7) / 8;

                        data[pos] = encData[pos];
                        data[pos + 1] = encData[pos + 1];
                        pos += 2;

                        byte[] tmp = RecoverKeyData(encAlgorithm, "/CFB/NoPadding", key, iv, encData, pos, encLen);
                        Array.Copy(tmp, 0, data, pos, encLen);
                        pos += encLen;

                        if (i != 3)
                        {
                            Array.Copy(encData, pos - iv.Length, iv, 0, iv.Length);
                        }
                    }

                    //
                    // verify and copy checksum
                    //

                    data[pos] = encData[pos];
                    data[pos + 1] = encData[pos + 1];

                    int cs = ((encData[pos] << 8) & 0xff00) | (encData[pos + 1] & 0xff);
                    int calcCs = 0;
                    for (int j = 0; j < pos; j++)
                    {
                        calcCs += data[j] & 0xff;
                    }

                    calcCs &= 0xffff;
                    if (calcCs != cs)
                    {
                        throw new PgpException("Checksum mismatch: passphrase wrong, expected "
                            + cs.ToString("X")
                            + " found " + calcCs.ToString("X"));
                    }
                }

                return data;
            }
            catch (PgpException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new PgpException("Exception decrypting key", e);
            }
        }

        private static byte[] RecoverKeyData(SymmetricKeyAlgorithmTag encAlgorithm, string modeAndPadding,
            KeyParameter key, byte[] iv, byte[] keyData, int keyOff, int keyLen)
        {
            IBufferedCipher c;
            try
            {
                string cName = PgpUtilities.GetSymmetricCipherName(encAlgorithm);
                c = CipherUtilities.GetCipher(cName + modeAndPadding);
            }
            catch (Exception e)
            {
                throw new PgpException("Exception creating cipher", e);
            }

            c.Init(false, new ParametersWithIV(key, iv));

            return c.DoFinal(keyData, keyOff, keyLen);
        }

        /// <summary>Extract a <c>PgpPrivateKey</c> from this secret key's encrypted contents.</summary>
        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public PgpPrivateKey ExtractPrivateKey(char[] passPhrase)
        {
            return DoExtractPrivateKey(PgpUtilities.EncodePassPhrase(passPhrase, false), true);
        }

        /// <summary>Extract a <c>PgpPrivateKey</c> from this secret key's encrypted contents.</summary>
        /// <remarks>
        /// The passphrase is encoded to bytes using UTF8 (Encoding.UTF8.GetBytes).
        /// </remarks>
        public PgpPrivateKey ExtractPrivateKeyUtf8(char[] passPhrase)
        {
            return DoExtractPrivateKey(PgpUtilities.EncodePassPhrase(passPhrase, true), true);
        }

        /// <summary>Extract a <c>PgpPrivateKey</c> from this secret key's encrypted contents.</summary>
        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        public PgpPrivateKey ExtractPrivateKeyRaw(byte[] rawPassPhrase)
        {
            return DoExtractPrivateKey(rawPassPhrase, false);
        }

        internal PgpPrivateKey DoExtractPrivateKey(byte[] rawPassPhrase, bool clearPassPhrase)
        {
            if (IsPrivateKeyEmpty)
                return null;

            PublicKeyPacket pubPk = secret.PublicKeyPacket;
            try
            {
                byte[] data = ExtractKeyData(rawPassPhrase, clearPassPhrase);
                BcpgInputStream bcpgIn = BcpgInputStream.Wrap(new MemoryStream(data, false));
                AsymmetricKeyParameter privateKey;
                switch (pubPk.Algorithm)
                {
                case PublicKeyAlgorithmTag.RsaEncrypt:
                case PublicKeyAlgorithmTag.RsaGeneral:
                case PublicKeyAlgorithmTag.RsaSign:
                    RsaPublicBcpgKey rsaPub = (RsaPublicBcpgKey)pubPk.Key;
                    RsaSecretBcpgKey rsaPriv = new RsaSecretBcpgKey(bcpgIn);
                    RsaPrivateCrtKeyParameters rsaPrivSpec = new RsaPrivateCrtKeyParameters(
                        rsaPriv.Modulus,
                        rsaPub.PublicExponent,
                        rsaPriv.PrivateExponent,
                        rsaPriv.PrimeP,
                        rsaPriv.PrimeQ,
                        rsaPriv.PrimeExponentP,
                        rsaPriv.PrimeExponentQ,
                        rsaPriv.CrtCoefficient);
                    privateKey = rsaPrivSpec;
                    break;
                case PublicKeyAlgorithmTag.Dsa:
                    DsaPublicBcpgKey dsaPub = (DsaPublicBcpgKey)pubPk.Key;
                    DsaSecretBcpgKey dsaPriv = new DsaSecretBcpgKey(bcpgIn);
                    DsaParameters dsaParams = new DsaParameters(dsaPub.P, dsaPub.Q, dsaPub.G);
                    privateKey = new DsaPrivateKeyParameters(dsaPriv.X, dsaParams);
                    break;
                case PublicKeyAlgorithmTag.ECDH:
                    privateKey = GetECKey("ECDH", bcpgIn);
                    break;
                case PublicKeyAlgorithmTag.ECDsa:
                    privateKey = GetECKey("ECDSA", bcpgIn);
                    break;
                case PublicKeyAlgorithmTag.ElGamalEncrypt:
                case PublicKeyAlgorithmTag.ElGamalGeneral:
                    ElGamalPublicBcpgKey elPub = (ElGamalPublicBcpgKey)pubPk.Key;
                    ElGamalSecretBcpgKey elPriv = new ElGamalSecretBcpgKey(bcpgIn);
                    ElGamalParameters elParams = new ElGamalParameters(elPub.P, elPub.G);
                    privateKey = new ElGamalPrivateKeyParameters(elPriv.X, elParams);
                    break;
                default:
                    throw new PgpException("unknown public key algorithm encountered");
                }

                return new PgpPrivateKey(KeyId, pubPk, privateKey);
            }
            catch (PgpException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new PgpException("Exception constructing key", e);
            }
        }

        private ECPrivateKeyParameters GetECKey(string algorithm, BcpgInputStream bcpgIn)
        {
            ECPublicBcpgKey ecdsaPub = (ECPublicBcpgKey)secret.PublicKeyPacket.Key;
            ECSecretBcpgKey ecdsaPriv = new ECSecretBcpgKey(bcpgIn);
            return new ECPrivateKeyParameters(algorithm, ecdsaPriv.X, ecdsaPub.CurveOid);
        }

        private static byte[] Checksum(
            bool	useSha1,
            byte[]	bytes,
            int		length)
        {
            if (useSha1)
            {
                try
                {
                    IDigest dig = DigestUtilities.GetDigest("SHA1");
                    dig.BlockUpdate(bytes, 0, length);
                    return DigestUtilities.DoFinal(dig);
                }
                //catch (NoSuchAlgorithmException e)
                catch (Exception e)
                {
                    throw new PgpException("Can't find SHA-1", e);
                }
            }
            else
            {
                int Checksum = 0;
                for (int i = 0; i != length; i++)
                {
                    Checksum += bytes[i];
                }

                return new byte[] { (byte)(Checksum >> 8), (byte)Checksum };
            }
        }

        public byte[] GetEncoded()
        {
            MemoryStream bOut = new MemoryStream();
            Encode(bOut);
            return bOut.ToArray();
        }

        public void Encode(
            Stream outStr)
        {
            BcpgOutputStream bcpgOut = BcpgOutputStream.Wrap(outStr);

            bcpgOut.WritePacket(secret);
            if (pub.trustPk != null)
            {
                bcpgOut.WritePacket(pub.trustPk);
            }

            if (pub.subSigs == null) // is not a sub key
            {
                foreach (PgpSignature keySig in pub.keySigs)
                {
                    keySig.Encode(bcpgOut);
                }

                for (int i = 0; i != pub.ids.Count; i++)
                {
                    object pubID = pub.ids[i];
                    if (pubID is string)
                    {
                        string id = (string) pubID;
                        bcpgOut.WritePacket(new UserIdPacket(id));
                    }
                    else
                    {
                        PgpUserAttributeSubpacketVector v = (PgpUserAttributeSubpacketVector) pubID;
                        bcpgOut.WritePacket(new UserAttributePacket(v.ToSubpacketArray()));
                    }

                    if (pub.idTrusts[i] != null)
                    {
                        bcpgOut.WritePacket((ContainedPacket)pub.idTrusts[i]);
                    }

                    foreach (PgpSignature sig in (IList) pub.idSigs[i])
                    {
                        sig.Encode(bcpgOut);
                    }
                }
            }
            else
            {
                foreach (PgpSignature subSig in pub.subSigs)
                {
                    subSig.Encode(bcpgOut);
                }
            }

            // TODO Check that this is right/necessary
            //bcpgOut.Finish();
        }

        /// <summary>
        /// Return a copy of the passed in secret key, encrypted using a new password
        /// and the passed in algorithm.
        /// </summary>
        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        /// <param name="key">The PgpSecretKey to be copied.</param>
        /// <param name="oldPassPhrase">The current password for the key.</param>
        /// <param name="newPassPhrase">The new password for the key.</param>
        /// <param name="newEncAlgorithm">The algorithm to be used for the encryption.</param>
        /// <param name="rand">Source of randomness.</param>
        public static PgpSecretKey CopyWithNewPassword(
            PgpSecretKey				key,
            char[]						oldPassPhrase,
            char[]						newPassPhrase,
            SymmetricKeyAlgorithmTag	newEncAlgorithm,
            SecureRandom				rand)
        {
            return DoCopyWithNewPassword(key, PgpUtilities.EncodePassPhrase(oldPassPhrase, false),
                PgpUtilities.EncodePassPhrase(newPassPhrase, false), true, newEncAlgorithm, rand);
        }

        /// <summary>
        /// Return a copy of the passed in secret key, encrypted using a new password
        /// and the passed in algorithm.
        /// </summary>
        /// <remarks>
        /// The passphrase is encoded to bytes using UTF8 (Encoding.UTF8.GetBytes).
        /// </remarks>
        /// <param name="key">The PgpSecretKey to be copied.</param>
        /// <param name="oldPassPhrase">The current password for the key.</param>
        /// <param name="newPassPhrase">The new password for the key.</param>
        /// <param name="newEncAlgorithm">The algorithm to be used for the encryption.</param>
        /// <param name="rand">Source of randomness.</param>
        public static PgpSecretKey CopyWithNewPasswordUtf8(
            PgpSecretKey				key,
            char[]						oldPassPhrase,
            char[]						newPassPhrase,
            SymmetricKeyAlgorithmTag	newEncAlgorithm,
            SecureRandom				rand)
        {
            return DoCopyWithNewPassword(key, PgpUtilities.EncodePassPhrase(oldPassPhrase, true),
                PgpUtilities.EncodePassPhrase(newPassPhrase, true), true, newEncAlgorithm, rand);
        }

        /// <summary>
        /// Return a copy of the passed in secret key, encrypted using a new password
        /// and the passed in algorithm.
        /// </summary>
        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        /// <param name="key">The PgpSecretKey to be copied.</param>
        /// <param name="rawOldPassPhrase">The current password for the key.</param>
        /// <param name="rawNewPassPhrase">The new password for the key.</param>
        /// <param name="newEncAlgorithm">The algorithm to be used for the encryption.</param>
        /// <param name="rand">Source of randomness.</param>
        public static PgpSecretKey CopyWithNewPasswordRaw(
            PgpSecretKey				key,
            byte[]						rawOldPassPhrase,
            byte[]						rawNewPassPhrase,
            SymmetricKeyAlgorithmTag	newEncAlgorithm,
            SecureRandom				rand)
        {
            return DoCopyWithNewPassword(key, rawOldPassPhrase, rawNewPassPhrase, false, newEncAlgorithm, rand);
        }

        internal static PgpSecretKey DoCopyWithNewPassword(
            PgpSecretKey				key,
            byte[]						rawOldPassPhrase,
            byte[]						rawNewPassPhrase,
            bool                        clearPassPhrase,
            SymmetricKeyAlgorithmTag	newEncAlgorithm,
            SecureRandom				rand)
        {
            if (key.IsPrivateKeyEmpty)
                throw new PgpException("no private key in this SecretKey - public key present only.");

            byte[]	rawKeyData = key.ExtractKeyData(rawOldPassPhrase, clearPassPhrase);
            int		s2kUsage = key.secret.S2kUsage;
            byte[]	iv = null;
            S2k		s2k = null;
            byte[]	keyData;
            PublicKeyPacket pubKeyPacket = key.secret.PublicKeyPacket;

            if (newEncAlgorithm == SymmetricKeyAlgorithmTag.Null)
            {
                s2kUsage = SecretKeyPacket.UsageNone;
                if (key.secret.S2kUsage == SecretKeyPacket.UsageSha1)   // SHA-1 hash, need to rewrite Checksum
                {
                    keyData = new byte[rawKeyData.Length - 18];

                    Array.Copy(rawKeyData, 0, keyData, 0, keyData.Length - 2);

                    byte[] check = Checksum(false, keyData, keyData.Length - 2);

                    keyData[keyData.Length - 2] = check[0];
                    keyData[keyData.Length - 1] = check[1];
                }
                else
                {
                    keyData = rawKeyData;
                }
            }
            else
            {
                if (s2kUsage == SecretKeyPacket.UsageNone)
                {
                    s2kUsage = SecretKeyPacket.UsageChecksum;
                }

                try
                {
                    if (pubKeyPacket.Version >= 4)
                    {
                        keyData = EncryptKeyDataV4(rawKeyData, newEncAlgorithm, HashAlgorithmTag.Sha1, rawNewPassPhrase, clearPassPhrase, rand, out s2k, out iv);
                    }
                    else
                    {
                        keyData = EncryptKeyDataV3(rawKeyData, newEncAlgorithm, rawNewPassPhrase, clearPassPhrase, rand, out s2k, out iv);
                    }
                }
                catch (PgpException e)
                {
                    throw e;
                }
                catch (Exception e)
                {
                    throw new PgpException("Exception encrypting key", e);
                }
            }

            SecretKeyPacket secret;
            if (key.secret is SecretSubkeyPacket)
            {
                secret = new SecretSubkeyPacket(pubKeyPacket, newEncAlgorithm, s2kUsage, s2k, iv, keyData);
            }
            else
            {
                secret = new SecretKeyPacket(pubKeyPacket, newEncAlgorithm, s2kUsage, s2k, iv, keyData);
            }

            return new PgpSecretKey(secret, key.pub);
        }

        /// <summary>Replace the passed the public key on the passed in secret key.</summary>
        /// <param name="secretKey">Secret key to change.</param>
        /// <param name="publicKey">New public key.</param>
        /// <returns>A new secret key.</returns>
        /// <exception cref="ArgumentException">If KeyId's do not match.</exception>
        public static PgpSecretKey ReplacePublicKey(
            PgpSecretKey	secretKey,
            PgpPublicKey	publicKey)
        {
            if (publicKey.KeyId != secretKey.KeyId)
                throw new ArgumentException("KeyId's do not match");

            return new PgpSecretKey(secretKey.secret, publicKey);
        }

        private static byte[] EncryptKeyDataV3(
            byte[]						rawKeyData,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            byte[]						rawPassPhrase,
            bool                        clearPassPhrase,
            SecureRandom				random,
            out S2k						s2k,
            out byte[]					iv)
        {
            // Version 2 or 3 - RSA Keys only

            s2k = null;
            iv = null;

            KeyParameter encKey = PgpUtilities.DoMakeKeyFromPassPhrase(encAlgorithm, s2k, rawPassPhrase, clearPassPhrase);

            byte[] keyData = new byte[rawKeyData.Length];

            //
            // process 4 numbers
            //
            int pos = 0;
            for (int i = 0; i != 4; i++)
            {
                int encLen = (((rawKeyData[pos] << 8) | (rawKeyData[pos + 1] & 0xff)) + 7) / 8;

                keyData[pos] = rawKeyData[pos];
                keyData[pos + 1] = rawKeyData[pos + 1];

                byte[] tmp;
                if (i == 0)
                {
                    tmp = EncryptData(encAlgorithm, encKey, rawKeyData, pos + 2, encLen, random, ref iv);
                }
                else
                {
                    byte[] tmpIv = Arrays.CopyOfRange(keyData, pos - iv.Length, pos);

                    tmp = EncryptData(encAlgorithm, encKey, rawKeyData, pos + 2, encLen, random, ref tmpIv);
                }

                Array.Copy(tmp, 0, keyData, pos + 2, tmp.Length);
                pos += 2 + encLen;
            }

            //
            // copy in checksum.
            //
            keyData[pos] = rawKeyData[pos];
            keyData[pos + 1] = rawKeyData[pos + 1];

            return keyData;
        }

        private static byte[] EncryptKeyDataV4(
            byte[]						rawKeyData,
            SymmetricKeyAlgorithmTag	encAlgorithm,
            HashAlgorithmTag            hashAlgorithm,
            byte[]						rawPassPhrase,
            bool                        clearPassPhrase,
            SecureRandom				random,
            out S2k						s2k,
            out byte[]					iv)
        {
            s2k = PgpUtilities.GenerateS2k(hashAlgorithm, 0x60, random);

            KeyParameter key = PgpUtilities.DoMakeKeyFromPassPhrase(encAlgorithm, s2k, rawPassPhrase, clearPassPhrase);

            iv = null;
            return EncryptData(encAlgorithm, key, rawKeyData, 0, rawKeyData.Length, random, ref iv);
        }

        private static byte[] EncryptData(
            SymmetricKeyAlgorithmTag	encAlgorithm,
            KeyParameter                key,
            byte[]						data,
            int                         dataOff,
            int                         dataLen,
            SecureRandom				random,
            ref byte[]                  iv)
        {
            IBufferedCipher c;
            try
            {
                string cName = PgpUtilities.GetSymmetricCipherName(encAlgorithm);
                c = CipherUtilities.GetCipher(cName + "/CFB/NoPadding");
            }
            catch (Exception e)
            {
                throw new PgpException("Exception creating cipher", e);
            }

            if (iv == null)
            {
                iv = PgpUtilities.GenerateIV(c.GetBlockSize(), random);
            }

            c.Init(true, new ParametersWithRandom(new ParametersWithIV(key, iv), random));

            return c.DoFinal(data, dataOff, dataLen);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys associating it with the passed in public key.
        /// </summary>
        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExpr(Stream inputStream, char[] passPhrase, PgpPublicKey pubKey)
        {
            return DoParseSecretKeyFromSExpr(inputStream, PgpUtilities.EncodePassPhrase(passPhrase, false), true, pubKey);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys associating it with the passed in public key.
        /// </summary>
        /// <remarks>
        /// The passphrase is encoded to bytes using UTF8 (Encoding.UTF8.GetBytes).
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExprUtf8(Stream inputStream, char[] passPhrase, PgpPublicKey pubKey)
        {
            return DoParseSecretKeyFromSExpr(inputStream, PgpUtilities.EncodePassPhrase(passPhrase, true), true, pubKey);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys associating it with the passed in public key.
        /// </summary>
        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExprRaw(Stream inputStream, byte[] rawPassPhrase, PgpPublicKey pubKey)
        {
            return DoParseSecretKeyFromSExpr(inputStream, rawPassPhrase, false, pubKey);
        }

        internal static PgpSecretKey DoParseSecretKeyFromSExpr(Stream inputStream, byte[] rawPassPhrase, bool clearPassPhrase, PgpPublicKey pubKey)
        {
            SXprUtilities.SkipOpenParenthesis(inputStream);

            string type = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
            if (type.Equals("protected-private-key"))
            {
                SXprUtilities.SkipOpenParenthesis(inputStream);

                string curveName;

                string keyType = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                if (keyType.Equals("ecc"))
                {
                    SXprUtilities.SkipOpenParenthesis(inputStream);

                    string curveID = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                    curveName = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());

                    SXprUtilities.SkipCloseParenthesis(inputStream);
                }
                else
                {
                    throw new PgpException("no curve details found");
                }

                byte[] qVal;

                SXprUtilities.SkipOpenParenthesis(inputStream);

                type = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                if (type.Equals("q"))
                {
                    qVal = SXprUtilities.ReadBytes(inputStream, inputStream.ReadByte());
                }
                else
                {
                    throw new PgpException("no q value found");
                }

                SXprUtilities.SkipCloseParenthesis(inputStream);

                byte[] dValue = GetDValue(inputStream, rawPassPhrase, clearPassPhrase, curveName);
                // TODO: check SHA-1 hash.

                return new PgpSecretKey(new SecretKeyPacket(pubKey.PublicKeyPacket, SymmetricKeyAlgorithmTag.Null, null, null,
                    new ECSecretBcpgKey(new BigInteger(1, dValue)).GetEncoded()), pubKey);
            }

            throw new PgpException("unknown key type found");
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys.
        /// </summary>
        /// <remarks>
        /// Conversion of the passphrase characters to bytes is performed using Convert.ToByte(), which is
        /// the historical behaviour of the library (1.7 and earlier).
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExpr(Stream inputStream, char[] passPhrase)
        {
            return DoParseSecretKeyFromSExpr(inputStream, PgpUtilities.EncodePassPhrase(passPhrase, false), true);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys.
        /// </summary>
        /// <remarks>
        /// The passphrase is encoded to bytes using UTF8 (Encoding.UTF8.GetBytes).
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExprUtf8(Stream inputStream, char[] passPhrase)
        {
            return DoParseSecretKeyFromSExpr(inputStream, PgpUtilities.EncodePassPhrase(passPhrase, true), true);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys.
        /// </summary>
        /// <remarks>
        /// Allows the caller to handle the encoding of the passphrase to bytes.
        /// </remarks>
        public static PgpSecretKey ParseSecretKeyFromSExprRaw(Stream inputStream, byte[] rawPassPhrase)
        {
            return DoParseSecretKeyFromSExpr(inputStream, rawPassPhrase, false);
        }

        /// <summary>
        /// Parse a secret key from one of the GPG S expression keys.
        /// </summary>
        internal static PgpSecretKey DoParseSecretKeyFromSExpr(Stream inputStream, byte[] rawPassPhrase, bool clearPassPhrase)
        {
            SXprUtilities.SkipOpenParenthesis(inputStream);

            string type = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
            if (type.Equals("protected-private-key"))
            {
                SXprUtilities.SkipOpenParenthesis(inputStream);

                string curveName;

                string keyType = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                if (keyType.Equals("ecc"))
                {
                    SXprUtilities.SkipOpenParenthesis(inputStream);

                    string curveID = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                    curveName = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());

                    if (Platform.StartsWith(curveName, "NIST "))
                    {
                        curveName = curveName.Substring("NIST ".Length);
                    }

                    SXprUtilities.SkipCloseParenthesis(inputStream);
                }
                else
                {
                    throw new PgpException("no curve details found");
                }

                byte[] qVal;

                SXprUtilities.SkipOpenParenthesis(inputStream);

                type = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
                if (type.Equals("q"))
                {
                    qVal = SXprUtilities.ReadBytes(inputStream, inputStream.ReadByte());
                }
                else
                {
                    throw new PgpException("no q value found");
                }

                PublicKeyPacket pubPacket = new PublicKeyPacket(PublicKeyAlgorithmTag.ECDsa, DateTime.UtcNow,
                    new ECDsaPublicBcpgKey(ECNamedCurveTable.GetOid(curveName), new BigInteger(1, qVal)));

                SXprUtilities.SkipCloseParenthesis(inputStream);

                byte[] dValue = GetDValue(inputStream, rawPassPhrase, clearPassPhrase, curveName);
                // TODO: check SHA-1 hash.

                return new PgpSecretKey(new SecretKeyPacket(pubPacket, SymmetricKeyAlgorithmTag.Null, null, null,
                    new ECSecretBcpgKey(new BigInteger(1, dValue)).GetEncoded()), new PgpPublicKey(pubPacket));
            }

            throw new PgpException("unknown key type found");
        }

        private static byte[] GetDValue(Stream inputStream, byte[] rawPassPhrase, bool clearPassPhrase, string curveName)
        {
            string type;
            SXprUtilities.SkipOpenParenthesis(inputStream);

            string protection;
            S2k s2k;
            byte[] iv;
            byte[] secKeyData;

            type = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());
            if (type.Equals("protected"))
            {
                protection = SXprUtilities.ReadString(inputStream, inputStream.ReadByte());

                SXprUtilities.SkipOpenParenthesis(inputStream);

                s2k = SXprUtilities.ParseS2k(inputStream);

                iv = SXprUtilities.ReadBytes(inputStream, inputStream.ReadByte());

                SXprUtilities.SkipCloseParenthesis(inputStream);

                secKeyData = SXprUtilities.ReadBytes(inputStream, inputStream.ReadByte());
            }
            else
            {
                throw new PgpException("protected block not found");
            }

            // TODO: recognise other algorithms
            KeyParameter key = PgpUtilities.DoMakeKeyFromPassPhrase(SymmetricKeyAlgorithmTag.Aes128, s2k, rawPassPhrase, clearPassPhrase);

            byte[] data = RecoverKeyData(SymmetricKeyAlgorithmTag.Aes128, "/CBC/NoPadding", key, iv, secKeyData, 0, secKeyData.Length);

            //
            // parse the secret key S-expr
            //
            Stream keyIn = new MemoryStream(data, false);

            SXprUtilities.SkipOpenParenthesis(keyIn);
            SXprUtilities.SkipOpenParenthesis(keyIn);
            SXprUtilities.SkipOpenParenthesis(keyIn);
            String name = SXprUtilities.ReadString(keyIn, keyIn.ReadByte());
            return SXprUtilities.ReadBytes(keyIn, keyIn.ReadByte());
        }
    }
}