Cannot able to verify a signed data

Question

Through smart card using a tool, I am signing data "Hello".

The output what i am getting is in hex format.

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

The respective signed data in string format I have saved in file signedData.txt.

._eÎ|-Š.ú°û†Î(„7-.c²5ú@J¶5ȯU±Êþý[ù.|Ûtc¿.[³mè-¶×.¯.^Ïxsã7.—.ù³@LgÍä|ÙKÓɆQŽ.„´0¬h– YËcåÈ(HÇ.èéüèɾ63.ð©5ÄÔ¿`f!\AH‘Ô»¯uuz³*Š(¸0Ñ´ki#‚-(w0.ÕÉ«A.ÁhmÙ€.òÁü2n"a'—œÝÃP3ªÛôº˜)úOâ ´¼Åž4ó¼=x.G¯– .oùA0×5RÓÞ…ãþ.·.M.s¸6ô¡Y¢~.P‹R¬´ï-Ù)Ù»ÈßógÅÑÙÀ.eh¨.›$’Në˜Ø°Ù.j

I am using Windows CryptoAPI for verification of this signed data.

I am opening the file signedData.txt and writing the data into the buffer " signedBuffer"

Then i am finding my certificate from the store and taking the handle of public key using

hPubKey = CryptImportPublicKeyInfo(hProv, ENCODING_TYPE, &pCertContext->pCertInfo->SubjectPublicKeyInfo, &hCertPubKey);

Then I am creating a hash object using CALG_SHA_256

hObject = CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHashObject);

Then adding my data with the hash object

CryptHashData(hhObject, Buffer, BufferLen, 0); // char Buffer = "Hello";

                                       // int BufferLen = strlen(Buffer );

In the last step i am verifying the signature using

CryptVerifySignature(hObject,signedBuffer,signedBufferBytes,hPubKey,NULL,0); /* signedBuffer contains signed data in string format */

/*signedBufferBytes has no. of bytes in the buffer */

but this signed data is not verified. Error code i am getting is 0x80090006 - Invalid Signature.

Public key In hex format is :

30 82 01 0a 02 82 01 01 00 b8 f8 dc 2c a5 03 84 ba 72 c6 0e 03 89 51 6f 39 a8 41 e3 49 b3 f7 14 31 d3 43 b7 fc 1f 61 c2 43 b0 77 9e 19 af f4 8b 02 99 72 c1 17 21 1d 23 da ab 53 54 74 33 e4 ab 9d 82 d2 68 33 9a b5 9c 99 cb f0 12 e0 f8 44 4f e8 91 3f 60 ed ca fa 3b 40 bd 64 50 92 d3 c2 c1 48 ad 24 3e ca 64 2c 50 a9 01 b5 9f f4 a4 46 e5 84 e9 a4 87 41 86 a1 7a 7f fc a6 f0 e0 b1 de f0 c1 f2 5d c8 84 16 15 4d e4 df 43 43 3a cd ad ec eb af 1b 9c a7 5c 40 dc ae 1f 71 6e a4 c6 0f dd 3e 3c c8 0d 25 4c 61 74 df aa ed b5 d5 b9 06 6a 8e b0 b7 c0 e6 c9 bf db b1 07 2e a2 76 aa e7 28 1c 8d 32 4e b3 58 1d 34 89 96 ed 3e da 29 e0 1e c9 c2 2e 18 19 a6 ba 91 32 b7 85 97 87 92 16 c5 01 b4 4f 57 5c 56 1b f5 f4 6a 29 6b 2e 51 8b f5 4c 6f b8 fd cb 09 d9 fd 66 09 04 49 b6 ba 7e d0 af 70 3a 51 41 5a a5 04 bf 02 03 01 00 01

The Signature buffer now I am using is:

BYTE            bSignatureBuf[]     = {
        0x6A, 0x2E, 0xD9, 0xB0, 0xD8, 0x98, 0xEB, 0x4E, 0x92, 0x24, 0x9B, 0x12, 0xA8, 0x68, 0x65, 0x0C,
        0xC0, 0xD9, 0xD1, 0xC5, 0x67, 0xF3, 0xDF, 0xC8, 0xBB, 0xD9, 0x9D, 0x29, 0xD9, 0x2D, 0xEF, 0xB4,
        0xAC, 0x52, 0x8B, 0x50, 0x05, 0x7E, 0xA2, 0x59, 0xA1, 0xF4, 0x36, 0xB8, 0x73, 0x1A, 0x4D, 0x15,
        0xB7, 0x0B, 0xFE, 0xE3, 0x85, 0xDE, 0xD3, 0x52, 0x35, 0xD7, 0x30, 0x41, 0xF9, 0x6F, 0x06, 0x20,
        0x96, 0xAF, 0x47, 0x01, 0x78, 0x3D, 0xBC, 0xF3, 0x34, 0x90, 0x9E, 0xC5, 0xBC, 0xB4, 0xE2, 0x4F,
        0xFA, 0x29, 0x98, 0xBA, 0xF4, 0xDB, 0xAA, 0x33, 0x50, 0xC3, 0xDD, 0x9C, 0x97, 0x27, 0x61, 0x22,
        0x6E, 0x32, 0xFC, 0xC1, 0xF2, 0x0F, 0x80, 0xD9, 0x6D, 0x68, 0xC1, 0x17, 0x41, 0xAB, 0xC9, 0xD5,
        0x05, 0x30, 0x77, 0x28, 0x2D, 0x82, 0x23, 0x69, 0x6B, 0xB4, 0xD1, 0x30, 0xB8, 0x28, 0x8A, 0x2A,
        0xB3, 0x7A, 0x75, 0x75, 0xAF, 0xBB, 0xD4, 0x91, 0x48, 0x8F, 0x41, 0x5C, 0x21, 0x66, 0x60, 0xBF,
        0xD4, 0xC4, 0x35, 0xA9, 0xF0, 0x0A, 0x33, 0x36, 0xBE, 0xC9, 0xE8, 0xFC, 0xE9, 0xE8, 0x1D, 0xC7,
        0x48, 0x28, 0xC8, 0xE5, 0x63, 0xCB, 0x59, 0x96, 0x68, 0xAC, 0x30, 0xB4, 0x81, 0x84, 0x1E, 0x8E,
        0x51, 0x86, 0xC9, 0xD3, 0x4B, 0xD9, 0x7C, 0xE4, 0xCD, 0x67, 0x4C, 0x40, 0xB3, 0xF9, 0x0E, 0x97,
        0xC2, 0x02, 0x37, 0xE3, 0x73, 0x78, 0xCF, 0x5E, 0x0A, 0xAF, 0x90, 0x2E, 0xD7, 0xB6, 0x2D, 0xE8,
        0x6D, 0xB3, 0x5B, 0x16, 0xBF, 0x63, 0x74, 0xDB, 0x7C, 0x1B, 0xF9, 0x5B, 0xFD, 0xFE, 0xCA, 0xB1,
        0x7F, 0x55, 0xAF, 0x90, 0xC8, 0x35, 0xB6, 0x4A, 0x40, 0xFA, 0x35, 0xB2, 0x63, 0x04, 0x2D, 0x37,
        0x84, 0x90, 0x28, 0xCE, 0x86, 0xFB, 0xB0, 0xFA, 0x0A, 0x8A, 0x2D, 0x7C, 0xCE, 0x65, 0x5F, 0x14
    };

Answer 1

First of all, you should not treat your binary data as text, as given in the comments.

Even more important is that your signature has been generated using PKCS#1 SHA-1 and your hash function specifies SHA-256 - presumably using PKCS#1 [^1]. You have to use identical hash function during signature generation and verification.

You can see the hash function used by looking up the OID in the ASN.1 description after decrypting your signature with the public key (in case you are wondering how to find out the hash function used).

Also note this little remark from the API:

The native cryptography API uses little-endian byte order (ed: for the signature bytes)

note that the non-M$ world uses big-endian byte order.

[^1]: as usual Microsoft does not specify the exact protocols they are applying [^2]

[^2]: this should view correctly once stackoverflow makes the tiny effort to implement markdown footnotes